1.
Personal computer
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A personal computer is a multi-purpose electronic computer whose size, capabilities, and price make it feasible for individual use. PCs are intended to be operated directly by a end-user, rather than by an expert or technician. In the 2010s, PCs are typically connected to the Internet, allowing access to the World Wide Web, personal computers may be connected to a local area network, either by a cable or a wireless connection. In the 2010s, a PC may be, a multi-component desktop computer, designed for use in a location a laptop computer, designed for easy portability or a tablet computer. In the 2010s, PCs run using a system, such as Microsoft Windows, Linux. The very earliest microcomputers, equipped with a front panel, required hand-loading of a program to load programs from external storage. Before long, automatic booting from permanent read-only memory became universal, in the 2010s, users have access to a wide range of commercial software, free software and free and open-source software, which are provided in ready-to-run or ready-to-compile form. Since the early 1990s, Microsoft operating systems and Intel hardware have dominated much of the computer market, first with MS-DOS. Alternatives to Microsofts Windows operating systems occupy a minority share of the industry and these include Apples OS X and free open-source Unix-like operating systems such as Linux and Berkeley Software Distribution. Advanced Micro Devices provides the alternative to Intels processors. PC is an initialism for personal computer, some PCs, including the OLPC XOs, are equipped with x86 or x64 processors but not designed to run Microsoft Windows. PC is used in contrast with Mac, an Apple Macintosh computer and this sense of the word is used in the Get a Mac advertisement campaign that ran between 2006 and 2009, as well as its rival, Im a PC campaign, that appeared in 2008. Since Apples transition to Intel processors starting 2005, all Macintosh computers are now PCs, the “brain” may one day come down to our level and help with our income-tax and book-keeping calculations. But this is speculation and there is no sign of it so far, in the history of computing there were many examples of computers designed to be used by one person, as opposed to terminals connected to mainframe computers. Using the narrow definition of operated by one person, the first personal computer was the ENIAC which became operational in 1946 and it did not meet further definitions of affordable or easy to use. An example of an early single-user computer was the LGP-30, created in 1956 by Stan Frankel and used for science and it came with a retail price of $47, 000—equivalent to about $414,000 today. Introduced at the 1965 New York Worlds Fair, the Programma 101 was a programmable calculator described in advertisements as a desktop computer. It was manufactured by the Italian company Olivetti and invented by the Italian engineer Pier Giorgio Perotto, the Soviet MIR series of computers was developed from 1965 to 1969 in a group headed by Victor Glushkov
2.
Operating system
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An operating system is system software that manages computer hardware and software resources and provides common services for computer programs. All computer programs, excluding firmware, require a system to function. Operating systems are found on many devices that contain a computer – from cellular phones, the dominant desktop operating system is Microsoft Windows with a market share of around 83. 3%. MacOS by Apple Inc. is in place, and the varieties of Linux is in third position. Linux distributions are dominant in the server and supercomputing sectors, other specialized classes of operating systems, such as embedded and real-time systems, exist for many applications. A single-tasking system can run one program at a time. Multi-tasking may be characterized in preemptive and co-operative types, in preemptive multitasking, the operating system slices the CPU time and dedicates a slot to each of the programs. Unix-like operating systems, e. g. Solaris, Linux, cooperative multitasking is achieved by relying on each process to provide time to the other processes in a defined manner. 16-bit versions of Microsoft Windows used cooperative multi-tasking, 32-bit versions of both Windows NT and Win9x, used preemptive multi-tasking. Single-user operating systems have no facilities to distinguish users, but may allow multiple programs to run in tandem, a distributed operating system manages a group of distinct computers and makes them appear to be a single computer. The development of networked computers that could be linked and communicate with each other gave rise to distributed computing, distributed computations are carried out on more than one machine. When computers in a work in cooperation, they form a distributed system. The technique is used both in virtualization and cloud computing management, and is common in large server warehouses, embedded operating systems are designed to be used in embedded computer systems. They are designed to operate on small machines like PDAs with less autonomy and they are able to operate with a limited number of resources. They are very compact and extremely efficient by design, Windows CE and Minix 3 are some examples of embedded operating systems. A real-time operating system is a system that guarantees to process events or data by a specific moment in time. A real-time operating system may be single- or multi-tasking, but when multitasking, early computers were built to perform a series of single tasks, like a calculator. Basic operating system features were developed in the 1950s, such as resident monitor functions that could run different programs in succession to speed up processing
3.
Interactive Systems Corporation
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Interactive Systems Corporation was a US-based software company and the first vendor of the Unix operating system outside AT&T, operating from Santa Monica, California. ISC was acquired by the Eastman Kodak Company in 1988, which sold its ISC Unix operating system assets to Sun Microsystems on September 26,1991, Kodak sold the remaining parts of ISC to SHL Systemhouse Inc in 1993. ISCs 1977 offering, IS/1, was a Version 6 Unix variant enhanced for office automation running on the PDP-11, iS/3 and IS/5 were enhanced versions of Unix System III and System V for PDP-11 and VAX. ISC Unix ports to the IBM PC included a variant of System III, developed under contract to IBM, known as PC/IX, with later versions branded 386/ix, ISC was AT&Ts Principal Publisher for System V.4 on the Intel platform. ISC was also involved in the development of VM/IX and IX/370, according to Bob Blake, the PC/IX product manager for IBM, their primary objective was to make a credible Unix system - not try to IBM-ize the product. PC/IX was not however the first Unix port to the XT, venix/86 preceded PC/IX by about a year, although it was based on the older Version 7 Unix. The main addition to PC/IX was the INed screen editor from ISC, INed offered multiple windows and context-sensitive help, paragraph justification and margin changes, although it was not a fully fledged word processor. PC/IX omitted the System III FORTRAN compiler, the tar file archiver, one reason for not porting these was that in PC/IX individual applications were limited to a single segment of 64 KB of RAM. To achieve good performance, PC/IX directly addressed the XT hard-drive rather than doing this through the BIOS. Because of the lack of memory protection in the 8088 chips. The PC/IX distribution came on 19 floppy disks and was accompanied by a 1, installed, PC/IX took approximately 4.5 MB of disk space. An editorial by Bill Machrone in PC Magazine at the time of PC/IXs launch flagged the $900 price as a show stopper given its lack of compatibility with MS-DOS applications, PC/IX was succeeded by 386/ix in 1985, a System VR3 derivative. Later versions were termed Interactive UNIX System V/386 and based on System V3.2 and its SVR3.2 kernel meant diminished compatibility with other Unix ports in the early nineties, but Interactive Unix was praised by a PC Magazine reviewer for its stability. The last version was System V/386 Release 3.2 Version 4.1.1, official support ended on July 23,2006, five years after Sun withdrew the product from sale. Until version ISA3.0.1, Interactive Unix supported only 16 MB of RAM, in the next versions, it supported 256MB RAM and PCI bus. EISA versions always supported 256MB RAM, covers and compares PC/IX, Xenix, and Venix. Maurice J. Bach, The Design of the UNIX Operating System, ISBN 0-13-201799-7, IBM has snubbed both Microsofts multimillion dollar investment in Xenix and AT&Ts determination to establish System V as the dominant version on Unix. IBMs latest hot potato Interactive Unix Documentation
4.
Xenix
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Xenix is a discontinued version of the Unix operating system for various microcomputer platforms, licensed by Microsoft from AT&T Corporation in the late 1970s. The Santa Cruz Operation later acquired rights to the software. In the mid-to-late 1980s, Xenix was the most common Unix variant, Microsoft chairman Bill Gates said in 1996 that for a long time that company had the highest-volume AT&T Unix license. Bell Labs, the developer of Unix, was part of the regulated Bell System and it instead licensed the software to others. Because Microsoft was not able to license the UNIX name itself, Microsoft called Xenix a universal operating environment. The first version of Xenix was very close to the original UNIX version 7 source on the PDP-11, Microsoft said in 1981, and later versions were to incorporate its own fixes and improvements. The first port was for the Z8001 16-bit processor, the first customer ship was January 1981 for Central Data Corporation of Illinois, the first 8086 port was for the Altos Computer Systems non-PC-compatible 8600-series computers. Intel sold complete computers with Xenix under their Intel System 86 brand and this included processor boards like iSBC 86/12 and also MMU boards such as the iSBC309. The first Intel Xenix systems shipped in July 1982, seattle Computer Products also made 8086 computers bundled with Xenix, like their Gazelle II, which used the S-100 bus and was available in late 1983 or early 1984. There was also a port for IBM System 9000, SCO had initially worked on its own PDP-11 port of V7, called Dynix, but then struck an agreement with Microsoft for joint development and technology exchange on Xenix in 1982. In 1984, a port to the 68000-based Apple Lisa was jointly developed by SCO and Microsoft, the difficulty in porting to the various 8086 and Z8000-based machines, said Microsoft in its 1983 OEM directory, had been the lack of a standardized memory management unit and protection facilities. A generally available port to the unmapped Intel 8086/8088 architecture was done by The Santa Cruz Operation around 1983, SCO Xenix for the PC XT shipped sometime in 1984 and contained some enhancement from 4. 2BSD, it also supported the Micnet local area networking. The later 286 version of Xenix leveraged the integrated MMU present on this chip, the 286 Xenix was accompanied by new hardware from Xenix OEMs. For example, the Sperry PC/IT, an IBM PC AT clone, was advertised as capable of supporting eight simultaneous dumb terminal users under this version and it was followed by a System V.2 codebase in Xenix 5.0. Microsoft hopes that XENIX will become the choice for software production and exchange. Microsoft referred to its own MS-DOS as its single-user, single-tasking operating system, microsofts Chris Larson described MS-DOS2. 0s Xenix compatibility as the second most important feature. AT&T started selling System V, however, after the breakup of the Bell System, Microsoft, believing that it could not compete with Unixs developer, decided to abandon Xenix. The decision was not immediately transparent, which led to the term vaporware and it agreed with IBM to develop OS/2, and the Xenix team was assigned to that project
5.
MINIX
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MINIX is a POSIX-compliant, Unix-like computer operating system based on a microkernel architecture. Early versions of MINIX were created by Andrew S. Tanenbaum for educational purposes, starting with MINIX3, the primary aim of development shifted from education to the creation of a highly reliable and self-healing microkernel OS. MINIX is now developed as open-source software, MINIX was first released in 1987, with its complete source code made available to universities for study in courses and research. It has been free and open source software since it was re-licensed under the BSD license in April 2000, Andrew S. Tanenbaum created MINIX at Vrije Universiteit in Amsterdam to exemplify the principles conveyed in his textbook, Operating Systems, Design and Implementation. An abridged 12,000 lines of the C source code of the kernel, memory manager, prentice-Hall also released MINIX source code and binaries on floppy disk with a reference manual. MINIX1 was system-call compatible with Seventh Edition Unix, Tanenbaum originally developed MINIX for compatibility with the IBM PC and IBM PC/AT microcomputers available at the time. There were also ports to Intel 386 PC compatibles, National Semiconductor NS32532, ARM. Meiko Scientific used a version of MINIX as the basis for the MeikOS operating system for its transputer-based Computing Surface parallel computers. A version of MINIX running as a process under SunOS and Solaris was also available. Demand for the 68k-based architectures waned, however, and MINIX2.0, released in 1997, was available for the x86. It was the subject of the edition of Tanenbaums textbook. MINIX2.0 added POSIX.1 compliance, support for 386 and later processors in 32-bit mode, unofficial ports of MINIX2.0.2 to the 68020-based ISICAD Prisma 700 workstation and the Hitachi SH3-based HP Jornada 680/690 PDA were also developed. Minix-vmd is a variant of MINIX2 for Intel IA-32-compatible processors, MINIX3 was publicly announced on 24 October 2005 by Andrew Tanenbaum during his keynote speech on top of the ACM Symposium Operating Systems Principles conference. MINIX3 currently supports IA-32 and ARM architecture systems, version 3.1.5 was released 5 November 2009. It contains X11, emacs, vi, cc, gcc, perl, python, ash, bash, zsh, ftp, ssh, telnet, pine, with the addition of X11, this version marks the transition away from a text-only system. It can also withstand driver crashes, in many cases it can automatically restart drivers without affecting running processes. In this way, MINIX is self-healing and can be used in applications demanding high reliability, MINIX3 also has support for virtual memory management, making it suitable for desktop OS use. Desktop applications such as Firefox and OpenOffice. org are not yet available for MINIX3 however
6.
Central processing unit
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The computer industry has used the term central processing unit at least since the early 1960s. The form, design and implementation of CPUs have changed over the course of their history, most modern CPUs are microprocessors, meaning they are contained on a single integrated circuit chip. An IC that contains a CPU may also contain memory, peripheral interfaces, some computers employ a multi-core processor, which is a single chip containing two or more CPUs called cores, in that context, one can speak of such single chips as sockets. Array processors or vector processors have multiple processors that operate in parallel, there also exists the concept of virtual CPUs which are an abstraction of dynamical aggregated computational resources. Early computers such as the ENIAC had to be rewired to perform different tasks. Since the term CPU is generally defined as a device for software execution, the idea of a stored-program computer was already present in the design of J. Presper Eckert and John William Mauchlys ENIAC, but was initially omitted so that it could be finished sooner. On June 30,1945, before ENIAC was made, mathematician John von Neumann distributed the paper entitled First Draft of a Report on the EDVAC and it was the outline of a stored-program computer that would eventually be completed in August 1949. EDVAC was designed to perform a number of instructions of various types. Significantly, the programs written for EDVAC were to be stored in high-speed computer memory rather than specified by the wiring of the computer. This overcame a severe limitation of ENIAC, which was the considerable time, with von Neumanns design, the program that EDVAC ran could be changed simply by changing the contents of the memory. Early CPUs were custom designs used as part of a larger, however, this method of designing custom CPUs for a particular application has largely given way to the development of multi-purpose processors produced in large quantities. This standardization began in the era of discrete transistor mainframes and minicomputers and has accelerated with the popularization of the integrated circuit. The IC has allowed increasingly complex CPUs to be designed and manufactured to tolerances on the order of nanometers, both the miniaturization and standardization of CPUs have increased the presence of digital devices in modern life far beyond the limited application of dedicated computing machines. Modern microprocessors appear in electronic devices ranging from automobiles to cellphones, the so-called Harvard architecture of the Harvard Mark I, which was completed before EDVAC, also utilized a stored-program design using punched paper tape rather than electronic memory. Relays and vacuum tubes were used as switching elements, a useful computer requires thousands or tens of thousands of switching devices. The overall speed of a system is dependent on the speed of the switches, tube computers like EDVAC tended to average eight hours between failures, whereas relay computers like the Harvard Mark I failed very rarely. In the end, tube-based CPUs became dominant because the significant speed advantages afforded generally outweighed the reliability problems, most of these early synchronous CPUs ran at low clock rates compared to modern microelectronic designs. Clock signal frequencies ranging from 100 kHz to 4 MHz were very common at this time, the design complexity of CPUs increased as various technologies facilitated building smaller and more reliable electronic devices
7.
IBM Personal Computer
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The IBM Personal Computer, commonly known as the IBM PC, is the original version and progenitor of the IBM PC compatible hardware platform. It is IBM model number 5150, and was introduced on August 12,1981 and it was created by a team of engineers and designers under the direction of Don Estridge of the IBM Entry Systems Division in Boca Raton, Florida. IBM compatible became an important criterion for sales growth, only the Apple Macintosh family kept significant market share without compatibility with the IBM personal computer, International Business Machines, one of the worlds largest companies, had a 62% share of the mainframe computer market in 1981. Its share of the computer market, however, had declined from 60% in 1970 to 32% in 1980. In 1979 BusinessWeek asked, Is IBM just another stodgy, mature company, by 1981 its stock price had declined by 22%. IBMs earnings for the first half the year grew by 5. 3%—one third of the inflation rate—while those of minicomputer maker Digital Equipment Corporation grew by more than 35%. B. M, No longer dominates the computer business. IBM wished to avoid the outcome with the new personal computer industry, dominated by the Commodore PET, Atari 8-bit family, Apple II, Tandy Corporations TRS-80. With $150 million in sales by 1979 and projected growth of more than 40% in the early 1980s. The Japanese project, codenamed Go, ended before the 1981 release of the American-designed IBM PC codenamed Chess, whether IBM had waited too long to enter an industry in which Apple and others were already successful was unclear. An observer stated that IBM bringing out a computer would be like teaching an elephant to tap dance. Successful microcomputer company Vector Graphics fiscal 1980 revenue was $12 million, the company only sold through its internal sales force, had no experience with resellers or retail stores, and did not introduce the first product designed to work with non-IBM equipment until 1980. Another observer claimed that IBM made decisions so slowly that, when tested, as with other large computer companies, its new products typically required about four to five years for development. IBM had to learn how to develop, mass-produce. The potential importance to microcomputers of a company so prestigious, that a saying in American companies stated No one ever got fired for buying IBM, was nonetheless clear. InfoWorld, which described itself as The Newsweekly for Microcomputer Users, stated that for my grandmother, is far and away the media star, not because of its features, but because it exists at all. When the number eight company in the Fortune 500 enters the field, the influence of a personal computer made by a company whose name has literally come to mean computer to most of the world is hard to contemplate. The editorial acknowledged that some factions in our industry have looked upon IBM as the enemy, desktop sized programmable calculators by Hewlett Packard had evolved into the HP9830 BASIC language computer by 1972. In 1972–1973 a team led by Dr. SCAMP emulated an IBM1130 minicomputer to run APL\1130, in 1973 APL was generally available only on mainframe computers, and most desktop sized microcomputers such as the Wang 2200 or HP9800 offered only BASIC
8.
IBM
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International Business Machines Corporation is an American multinational technology company headquartered in Armonk, New York, United States, with operations in over 170 countries. The company originated in 1911 as the Computing-Tabulating-Recording Company and was renamed International Business Machines in 1924, IBM manufactures and markets computer hardware, middleware and software, and offers hosting and consulting services in areas ranging from mainframe computers to nanotechnology. IBM is also a research organization, holding the record for most patents generated by a business for 24 consecutive years. IBM has continually shifted its business mix by exiting commoditizing markets and focusing on higher-value, also in 2014, IBM announced that it would go fabless, continuing to design semiconductors, but offloading manufacturing to GlobalFoundries. Nicknamed Big Blue, IBM is one of 30 companies included in the Dow Jones Industrial Average and one of the worlds largest employers, with nearly 380,000 employees. Known as IBMers, IBM employees have been awarded five Nobel Prizes, six Turing Awards, ten National Medals of Technology, in the 1880s, technologies emerged that would ultimately form the core of what would become International Business Machines. On June 16,1911, their four companies were amalgamated in New York State by Charles Ranlett Flint forming a fifth company, the Computing-Tabulating-Recording Company based in Endicott, New York. The five companies had 1,300 employees and offices and plants in Endicott and Binghamton, New York, Dayton, Ohio, Detroit, Michigan, Washington, D. C. and Toronto. They manufactured machinery for sale and lease, ranging from commercial scales and industrial time recorders, meat and cheese slicers, to tabulators and punched cards. Thomas J. Watson, Sr. fired from the National Cash Register Company by John Henry Patterson, called on Flint and, Watson joined CTR as General Manager then,11 months later, was made President when court cases relating to his time at NCR were resolved. Having learned Pattersons pioneering business practices, Watson proceeded to put the stamp of NCR onto CTRs companies and his favorite slogan, THINK, became a mantra for each companys employees. During Watsons first four years, revenues more than doubled to $9 million, Watson had never liked the clumsy hyphenated title of the CTR and in 1924 chose to replace it with the more expansive title International Business Machines. By 1933 most of the subsidiaries had been merged into one company, in 1937, IBMs tabulating equipment enabled organizations to process unprecedented amounts of data, its clients including the U. S. During the Second World War the company produced small arms for the American war effort, in 1949, Thomas Watson, Sr. created IBM World Trade Corporation, a subsidiary of IBM focused on foreign operations. In 1952, he stepped down after almost 40 years at the company helm, in 1957, the FORTRAN scientific programming language was developed. In 1961, IBM developed the SABRE reservation system for American Airlines, in 1963, IBM employees and computers helped NASA track the orbital flight of the Mercury astronauts. A year later it moved its headquarters from New York City to Armonk. The latter half of the 1960s saw IBM continue its support of space exploration, on April 7,1964, IBM announced the first computer system family, the IBM System/360
9.
Hard disk drive
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The platters are paired with magnetic heads, usually arranged on a moving actuator arm, which read and write data to the platter surfaces. Data is accessed in a manner, meaning that individual blocks of data can be stored or retrieved in any order. HDDs are a type of storage, retaining stored data even when powered off. Introduced by IBM in 1956, HDDs became the dominant secondary storage device for computers by the early 1960s. Continuously improved, HDDs have maintained this position into the era of servers. More than 200 companies have produced HDDs historically, though after extensive industry consolidation most current units are manufactured by Seagate, Toshiba, as of 2016, HDD production is growing, although unit shipments and sales revenues are declining. While SSDs have higher cost per bit, SSDs are replacing HDDs where speed, power consumption, small size, the primary characteristics of an HDD are its capacity and performance. Capacity is specified in unit prefixes corresponding to powers of 1000, the two most common form factors for modern HDDs are 3. 5-inch, for desktop computers, and 2. 5-inch, primarily for laptops. HDDs are connected to systems by standard interface cables such as PATA, SATA, Hard disk drives were introduced in 1956, as data storage for an IBM real-time transaction processing computer and were developed for use with general-purpose mainframe and minicomputers. The first IBM drive, the 350 RAMAC in 1956, was approximately the size of two medium-sized refrigerators and stored five million six-bit characters on a stack of 50 disks. In 1962 the IBM350 RAMAC disk storage unit was superseded by the IBM1301 disk storage unit, cylinder-mode read/write operations were supported, and the heads flew about 250 micro-inches above the platter surface. Motion of the head array depended upon a binary system of hydraulic actuators which assured repeatable positioning. The 1301 cabinet was about the size of three home refrigerators placed side by side, storing the equivalent of about 21 million eight-bit bytes, access time was about a quarter of a second. Also in 1962, IBM introduced the model 1311 disk drive, users could buy additional packs and interchange them as needed, much like reels of magnetic tape. Later models of removable pack drives, from IBM and others, became the norm in most computer installations, non-removable HDDs were called fixed disk drives. Some high-performance HDDs were manufactured with one head per track so that no time was lost physically moving the heads to a track, known as fixed-head or head-per-track disk drives they were very expensive and are no longer in production. In 1973, IBM introduced a new type of HDD code-named Winchester and its primary distinguishing feature was that the disk heads were not withdrawn completely from the stack of disk platters when the drive was powered down. Instead, the heads were allowed to land on an area of the disk surface upon spin-down
10.
IBM 3270 PC
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The IBM3270 PC, released in October 1983, was an IBM PC XT containing additional hardware which could emulate the behaviour of an IBM3270 terminal. It could therefore be used both as a computer, and as a terminal to a mainframe. IBM later released the 3270 AT, which was a design based on the IBM PC AT. They also released high-end graphics versions of the 3270 PC in both XT and AT variants, the XT-based versions were called 3270 PC/G and 3270 PC/GX and they used a different System Unit 5371, while their AT counterparts had System Unit 5373. The additional hardware occupied nearly all the expansion slots in the computer. It included a card which occupied 1-3 ISA slots, and supported CGA. The display resolution was 720×350, either on the matching 14-inch color monitor or in monochrome on an MDA monitor, a further expansion card intercepted scancodes from the 122-key 3270 keyboard, translating them into XT scancodes which were then sent to the normal keyboard connector. This keyboard, officially called the 5271 Keyboard Element, weighed 9.3 pounds, the final additional card provided the communication interface to the host mainframe. 3270 PC - original 3270 PC, initially offered in three different Models numbered 2,4, and 6, Model 2 had non-expandable memory of 256 KB and a single floppy drive. Model 4 had expandable memory, a floppy drive. Model 6 replaced one of the drives with a 10 MB hard disk. The 3270 PC suffered however from incompatibility problems with other XT hardware and this monochrome display was intended to provide a high-capacity text terminal for simultaneous mainframe sessions. Models 30,50, and 70 came with 640 KB RAM on the system board and they also reverted to the 5151/5272 Display Adapter. Models 31,51, and 71 reverted to 256 KB RAM on the board but were also shipped with an Expanded Memory Adapter with 1 MB RAM standard. Optionally these models could be equipped with up to 2 MB of XMA, Models P30/P50/P70 and P31/P51/P71 were like Models 30/50/70 and respectively 31/51/71 but with a 101-key keyboard replacing the 5271 Keyboard. Models 31/51/71 and all P-models, required version 3.0 of the Control Program, even the basic Model 12 had a parallel port and supported a mouse. The mouse was optional though even for Model 16, and had a list price of $340,3270 PC/GX - Extended APA graphics support provided by the IBM5378 Display Attachment Unit, shipped with a 19-inch color or monochrome monitor. Price at launch was $18,490, although adding the basic software, the basic 3270 PC could not be upgraded to the PC/G or PC/GX
11.
IBM 3270
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The IBM3270 is a class of block oriented computer terminal introduced by IBM in 1971 normally used to communicate with IBM mainframes. The 3270 was the successor to the IBM2260 display terminal, due to the text colour on the original models, these terminals are informally known as green screen terminals. Although IBM no longer manufactures 3270 terminals, the IBM3270 protocol is commonly used via terminal emulation to access mainframe-based applications. Accordingly, such applications are sometimes referred to as green screen applications, the 3270 series was designed to connect with mainframe computers, often at a remote location, using the technology then available in the early 1970s. Two of the design goals of 3270s are minimizing the amount of data transmitted. 3270 devices are clustered, with one or more displays or printers connected to a control unit, originally devices were connected to the control unit over coaxial cable, later token ring, twisted pair, or Ethernet connections were available. A local control unit attaches directly to the channel of a nearby mainframe, a remote control unit is connected to a communications line by a modem. Remote 3270 controllers are frequently multi-dropped, with multiple units on a line. In a data stream, both text and control are interspersed allowing an entire screen to be painted as an output operation. The concept of formatting in these devices allows the screen to be divided into fields for which numerous field attributes can be set, a field attribute occupies a physical location on the screen that also determines the beginning and end of a field. This technique enhances the terminal throughput of the CPU, and minimizes the data transmitted, some users familiar with character interrupt-driven terminal interfaces find this technique unusual. There is also a read buffer capability that transfers the entire content of the 3270-screen buffer including field attributes and this is mainly used for debugging purposes to preserve the application program screen contents while replacing it, temporarily, with debugging information. Early 3270s offered three types of keyboards, the typewriter keyboard came in both a 66 key version, with no programmed function keys, and a 78 key version with twelve. Both versions had two program attention keys, the data entry keyboard had five PF keys and two PA keys. The operator console keyboard had twelve PF keys and two PA keys, later 3270s had twenty-four PF keys and three PA keys. When one of these keys is pressed, it cause its control unit to generate an I/O interrupt to the host computer. Application program functions such as termination, page-up, page-down, or help can be invoked by a key press. In this way, the CPU is not interrupted at every keystroke, on the other hand, vi-like behaviour was not possible
12.
Random-access memory
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Random-access memory is a form of computer data storage which stores frequently used program instructions to increase the general speed of a system. A random-access memory device allows data items to be read or written in almost the same amount of time irrespective of the location of data inside the memory. RAM contains multiplexing and demultiplexing circuitry, to connect the lines to the addressed storage for reading or writing the entry. Usually more than one bit of storage is accessed by the same address, in todays technology, random-access memory takes the form of integrated circuits. RAM is normally associated with types of memory, where stored information is lost if power is removed. Other types of non-volatile memories exist that allow access for read operations. These include most types of ROM and a type of memory called NOR-Flash. Integrated-circuit RAM chips came into the market in the early 1970s, with the first commercially available DRAM chip, early computers used relays, mechanical counters or delay lines for main memory functions. Ultrasonic delay lines could only reproduce data in the order it was written, drum memory could be expanded at relatively low cost but efficient retrieval of memory items required knowledge of the physical layout of the drum to optimize speed. Latches built out of vacuum tube triodes, and later, out of transistors, were used for smaller and faster memories such as registers. Such registers were relatively large and too costly to use for large amounts of data, the first practical form of random-access memory was the Williams tube starting in 1947. It stored data as electrically charged spots on the face of a cathode ray tube, since the electron beam of the CRT could read and write the spots on the tube in any order, memory was random access. The capacity of the Williams tube was a few hundred to around a thousand bits, but it was smaller, faster. In fact, rather than the Williams tube memory being designed for the SSEM, magnetic-core memory was invented in 1947 and developed up until the mid-1970s. It became a form of random-access memory, relying on an array of magnetized rings. By changing the sense of each rings magnetization, data could be stored with one bit stored per ring, since every ring had a combination of address wires to select and read or write it, access to any memory location in any sequence was possible. Magnetic core memory was the form of memory system until displaced by solid-state memory in integrated circuits. Data was stored in the capacitance of each transistor, and had to be periodically refreshed every few milliseconds before the charge could leak away
13.
Floppy disk
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Floppy disks are read and written by a floppy disk drive. Floppy disks, initially as 8-inch media and later in 5¼-inch and 3½-inch sizes, were a form of data storage and exchange from the mid-1970s into the mid-2000s. These formats are usually handled by older equipment and these disks and associated drives were produced and improved upon by IBM and other companies such as Memorex, Shugart Associates, and Burroughs Corporation. The term floppy disk appeared in print as early as 1970, in 1976, Shugart Associates introduced the first 5¼-inch FDD. By 1978 there were more than 10 manufacturers producing such FDDs, there were competing floppy disk formats, with hard- and soft-sector versions and encoding schemes such as FM, MFM and GCR. The 5¼-inch format displaced the 8-inch one for most applications, the most common capacity of the 5¼-inch format in DOS-based PCs was 360 kB and in 1984 IBM introduced the 1.2 MB dual-sided floppy disk along with its PC-AT model. IBM started using the 720 kB double-density 3½-inch microfloppy disk on its Convertible laptop computer in 1986 and these disk drives could be added to older PC models. In 1988 IBM introduced a drive for 2.88 MB DSED diskettes in its top-of-the-line PS/2 models, throughout the early 1980s, limitations of the 5¼-inch format became clear. Originally designed to be practical than the 8-inch format, it was itself too large, as the quality of recording media grew. A number of solutions were developed, with drives at 2-, 2½-, 3-, 3½-, the large market share of the 5¼-inch format made it difficult for these new formats to gain significant market share. A variant on the Sony design, introduced in 1982 by a number of manufacturers, was then rapidly adopted. By the end of the 1980s, 5¼-inch disks had been superseded by 3½-inch disks, by the mid-1990s, 5¼-inch drives had virtually disappeared, as the 3½-inch disk became the predominant floppy disk. Floppy disks became ubiquitous during the 1980s and 1990s in their use with computers to distribute software, transfer data. Before hard disks became affordable to the population, floppy disks were often used to store a computers operating system. Most home computers from that period have a primary OS and BASIC stored as ROM, by the early 1990s, the increasing software size meant large packages like Windows or Adobe Photoshop required a dozen disks or more. In 1996, there were a five billion standard floppy disks in use. Then, distribution of packages was gradually replaced by CD-ROMs, DVDs. External USB-based floppy disk drives are available, many modern systems provide firmware support for booting from such drives
14.
Seagate Technology
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Seagate Technology PLC is an American data storage company. It was incorporated in 1978, as Shugart Technology, since 2010, the company is incorporated in Dublin, Ireland, with operational headquarters in Cupertino, California, United States. Seagate developed the first 5. 25-inch hard disk drive, the 5-megabyte ST-506 and they were a major supplier in the microcomputer market during the 1980s, especially after the introduction of the IBM XT in 1983. Today Seagate along with Western Digital dominates the HDD market, much of their growth has come through acquisition of competitors. In 1989, Seagate acquired Control Data Corporations Imprimis division, makers of CDCs HDD products, Seagate acquired Conner Peripherals in 1996, Maxtor in 2006, and Samsungs HDD business in 2011. Seagate Technology was incorporated on November 1,1978, and commenced operations with co-founders Al Shugart, Tom Mitchell, Doug Mahon, Finis Conner, the name was changed to Seagate Technology to avoid a lawsuit from Xeroxs subsidiary Shugart Associates. The companys first product, the 5-megabyte ST-506, was released in 1980 and it was the first hard disk to fit the 5. 25-inch form factor of the Shugart mini-floppy drive. The hard disk, which used a Modified Frequency Modulation encoding, was a hit, and was released in a 10-megabyte version. With this Seagate secured a contract as a major OEM supplier for the IBM XT, the large volumes of units sold to IBM, the then-dominant supplier of PCs, fueled Seagates early growth. In their first year, Seagate shipped $10 million of units to consumers, by 1983, the company shipped over 200,000 units for revenues of $110 million. The 20-megabyte version, the ST-225, and the 30-megabyte version and these were also made in SCSI versions. In 1983, Al Shugart was replaced as president by then chief operating officer, Tom Mitchell, Shugart continued to oversee corporate planning. By this point the company had a 45% market share of the hard drive market. In 1989, Seagate acquired Control Datas Imprimis Technology, CDCs disk storage division, in September 1991, Tom Mitchell resigned as president under pressure from the board of directors, with Al Shugart reassuming presidency of the company. Shugart refocused the company on its more lucrative markets, and on mainframe drives instead of external drives and this included a domestic partnership with Corning Inc. which began using a new glass ceramic compound to manufacture disk substrates. In 1991, Seagate also introduced the Barracuda HDDs, the industrys first hard disk with a 7200-RPM spindle speed, in May 1993, Seagate became the first company to cumulatively ship 50 million HDDs over its firms history. The following year Seagate Technology Inc moved from the Nasdaq exchange to the New York Stock Exchange, upon leaving, the company was the 17th-largest company in terms of trading volume on the Nasdaq exchange. In 1996, Seagate merged with Conner Peripherals to form worlds largest independent hard-drive manufacturer, in 1996, Seagate introduced the industrys first hard disk with a 10, 000-RPM spindle speed, the Cheetah 4LP
15.
ST-506
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ST-506 can refer to either the hard disk drive or its interface The ST-506 hard disk drive was the first 5.25 inch hard disk drive, introduced in 1980 by Shugart Technology. It stored up to 5 megabytes after formatting and cost US $1,500, the similar, 10-megabyte ST-412 was introduced in late 1981. The ST-225 was introduced shortly thereafter with 20 megabytes and half the height, all three used MFM encoding, a widely used coding scheme. A subsequent extension of the ST-412 interface used RLL encoding for a 50% increase in capacity, the ST-506 connected to a computer system through a disk controller. The ST-506 interface and its variants were adopted by numerous HDD manufacturers such that the interface became a de facto standards for disk drives well into the 1990s. The limitations of the ST-506 interface is 5.00 Mbit/s transfer rate,16 heads,4 drive units, number of tracks only increase the access time. In the ST-506 interface, the connects to a controller card with two data cables, while a third provides power. Four of the pins, HD SLCT0 through HD SLCT3, allow the selection among up to 16 heads, once the heads are properly positioned, data is read or written serially through a set of pins in the 20-pin data cable. The limited bandwidth of the cable was not an issue at the time and is not the factor that limited the performance of the system. However, the cable can sometimes be susceptible to high levels of noise. The ST-412 disk drive, among other improvements, added buffered seek capability to the interface, in this mode, the controller can send STEP pulses to the drive as fast as it can receive them, without having to wait for the mechanism to settle. An onboard microprocessor then moves the mechanism to the track as fast as possible. The ST-506 disk drive without buffered seek, averages 170 ms while the very similar ST412 disk drive with buffered seek averages 85 ms. By the late 1980s, ST-412 drives were capable of average seek times between 15 and 30 milliseconds. IDE, in effect, is a system for extending the computer bus so the controller can be built into the drive enclosure rather than having to be plugged into the computers backplane. This allows a controller card to talk to multiple drives, as well as reducing latency. In these systems, the details of the drive, like head selection and seeking, is entirely hidden from the host. These became known as smart drives, while ST-506-like devices retroactively became known as dumb, many other companies quickly introduced drives using the same connectors and signals, creating a hard drive standard based on the ST-506
16.
Asynchronous serial communication
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Asynchronous serial communication is a form of serial communication in which the communicating endpoints interfaces are not continuously synchronized by a common clock signal. Instead of a synchronization signal, the data stream contains synchronization information in form of start and stop signals, before and after each unit of transmission. The start signal prepares the receiver for arrival of data and the stop signal resets its state to enable triggering of a new sequence, a common kind of start-stop transmission is ASCII over RS-232, for example for use in teletypewriter operation. Mechanical teleprinters using 5-bit codes typically used a stop period of 1.5 bit times, very early electromechanical teletypewriters could demand 2 stop bits to allow mechanical impression without buffering. Having been re-synchronized, the technology of the day was enough to preserve bit-sync for the remainder of the character. The stop bits gave the time to recover before the next start bit. Early teleprinter systems used five data bits, typically with some variant of the Baudot code, very early experimental printing telegraph devices used only a start bit and required manual adjustment of the receiver mechanism speed to reliably decode characters. Automatic synchronization was required to keep the transmitting and receiving units in step and this was finally achieved by Howard Krum, who patented the start-stop method of synchronization. Shortly afterward a practical teleprinter was patented, some systems use automatic speed detection. These systems used either seven or eight data bits, transmitted least-significant bit first, between computers, the most common configuration used was 8N1, eight bit characters, with one start bit, one stop bit, and no parity bit. Thus 10 Baud times are used to send a single character, comparison of synchronous and asynchronous signalling Degree of start-stop distortion Synchronous serial communication Universal asynchronous receiver/transmitter Nelson, R. A. and Lovitt, K. M. History of Teletypewriter Development, Teletype Corporation, retrieved April 14,2005 Hobbs, Allan G. Five-unit codes, accessed 20 December 2007 Programming, Serial Data Communications at Wikibooks
17.
Serial port
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In computing, a serial port is a serial communication interface through which information transfers in or out one bit at a time. Throughout most of the history of computers, data was transferred through serial ports to devices such as modems, terminals. Modern computers without serial ports may require serial-to-USB converters to allow compatibility with RS-232 serial devices, serial ports are still used in applications such as industrial automation systems, scientific instruments, point of sale systems and some industrial and consumer products. Server computers may use a port as a control console for diagnostics. Network equipment often use serial console for configuration, serial ports are still used in these areas as they are simple, cheap and their console functions are highly standardized and widespread. A serial port requires very little supporting software from the host system, some computers, such as the IBM PC, use an integrated circuit called a UART. This IC converts characters to and from asynchronous serial form, implementing the timing and framing of data in hardware, very low-cost systems, such as some early home computers, would instead use the CPU to send the data through an output pin, using the bit-banging technique. Early home computers often had proprietary serial ports with pinouts and voltage levels incompatible with RS-232, low-cost processors now allow higher-speed, but more complex, serial communication standards such as USB and FireWire to replace RS-232. These make it possible to connect devices that would not have operated feasibly over slower serial connections, such as storage, sound. Many personal computer motherboards still have at least one serial port, small-form-factor systems and laptops may omit RS-232 connector ports to conserve space, but the electronics are still there. RS-232 has been standard for so long that the circuits needed to control a serial port became very cheap and often exist on a single chip, sometimes also with circuitry for a parallel port. The individual signals on a serial port are unidirectional and when connecting two devices the outputs of one device must be connected to the inputs of the other, devices are divided into two categories data terminal equipment and data circuit-terminating equipment. A line that is an output on a DTE device is an input on a DCE device and vice versa so a DCE device can be connected to a DTE device with a straight wired cable, conventionally, computers and terminals are DTE while modems and peripherals are DCE. If it is necessary to connect two DTE devices a cross-over null modem, in the form of either an adapter or a cable, generally, serial port connectors are gendered, only allowing connectors to mate with a connector of the opposite gender. With D-subminiature connectors, the male connectors have protruding pins, either type of connector can be mounted on equipment or a panel, or terminate a cable. Connectors mounted on DTE are likely to be male, and those mounted on DCE are likely to be female, however, this is far from universal, for instance, most serial printers have a female DB25 connector, but they are DTEs. The desire to supply serial interface cards with two ports required that IBM reduce the size of the connector to fit onto a single card back panel, a DE-9 connector also fits onto a card with a second DB-25 connector. Starting around the time of the introduction of the IBM PC-AT, serial ports were built with a 9-pin connector to save cost
18.
8250 UART
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The 8250 UART is an integrated circuit designed for implementing the interface for serial communications. The part was manufactured by the National Semiconductor Corporation. It was commonly used in PCs and related equipment such as printers or modems, the chip designations carry suffix letters for later versions of the same chip series. For example, the original 8250 was soon followed by the 8250A, in particular, the original 8250 could repeat transmission of a character if the CTS line was asserted asynchronously during the first transmission attempt. Due to the demand, other manufacturers soon began offering compatible chips. Western Digital offered WD8250 chip under Async Communications Interface Adapter and Async Communications Element names, the 16450 UART, commonly used in IBM PC/AT-series computers, improved on the 8250 by permitting higher serial line speeds. The line interface consists of, SOUT, SIN, /RTS, /DTR, DSR, /DCD, /CTS, /RI Clock interface, XIN, XOUT, /BAUDOUT, RCLK Computer interface, the interrupt signal is reset to low level upon the appropriate interrupt service or a reset operation. 8250 UART was introduced with the IBM PC, the 8250A and 8250B revisions were later released, and the 16450 was introduced with the IBM Personal Computer/AT. The main difference between releases was the maximum allowed communication speed, a very similar, but slightly incompatible variant of this chip is the Intel 8251. Serial and UART Tutorial archive. pcjs. org, National Semiconductor PC16450C/NS16450, PC8250A/INS8250A Universal Asynchronous Receiver Transmitter
19.
Power supply unit (computer)
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A power supply unit converts mains AC to low-voltage regulated DC power for the internal components of a computer. Modern personal computers universally use switched-mode power supplies, some power supplies have a manual switch for selecting input voltage, while others automatically adapt to the mains voltage. Most modern desktop computer power supplies conform to the ATX specification. While an ATX power supply is connected to the supply, it always provides a 5 Volt standby voltage so that the standby functions on the computer. ATX power supplies are turned on and off by a signal from the motherboard and they also provide a signal to the motherboard to indicate when the DC voltages are in spec, so that the computer is able to safely power up and boot. The most recent ATX PSU standard is version 2.31 of mid-2008, the desktop computer power supply changes alternating current from a wall socket to low-voltage direct current to operate the processor and peripheral devices. Several direct-current voltages are required, and they must be regulated with some accuracy to provide stable operation of the computer, a power supply rail or voltage rail refers to a single voltage provided by a power supply unit. Although the term is used in electronic engineering, many people, especially computer enthusiasts. First-generation microcomputer and home computer power supply units used a heavy step-down transformer, modern computers use switched-mode power supplies with a ferrite-cored high frequency transformer. The switched-mode supply is much lighter and less costly, and is more efficient, computer power supplies may have short circuit protection, overpower protection, overvoltage protection, undervoltage protection, overcurrent protection, and over temperature protection. Recent power supplies have a standby voltage available, to allow most of the system to be powered off. When the computer is powered down but the supply is still on, it can be started remotely via Wake-on-LAN. This standby voltage is generated by a power supply inside the unit. In older PSU designs, it was used to supply the voltage regulator, located on the side of the transformer. The regulator controls the switching transistors insulated by optocouplers or pulse transformers, for this reason, a detected shoutcut may cause to wait up to an hour, until it can successful power up again. This meantime is defined by the grid side located filter capacitors have been discharged by the installed bleeding resistors, Power supplies designed for worldwide use were equipped with an input voltage selector switch that allowed the user to configure the unit for use on local power grid. In the lower range, around 115 V, this switch is turned on changing the power grid voltage rectifier into a voltage doubler in delon circuit design. Connecting the unit configured for the range to a higher-voltage grid usually resulted in an immediate permanent damage
20.
Intel 8088
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The Intel 8088 microprocessor is a variant of the Intel 8086. Introduced on July 1,1979, the 8088 had an 8-bit external data bus instead of the 16-bit bus of the 8086, the 16-bit registers and the one megabyte address range were unchanged, however. In fact, according to the Intel documentation, the 8086 and 8088 have the execution unit —only the bus interface unit is different. The original IBM PC was based on the 8088, the 8088 was designed in Israel, at Intels Haifa laboratory, as were a large number of Intels processors. The prefetch queue of the 8088 was shortened to four bytes, from the 8086s six bytes, and these modifications of the basic 8086 design were one of the first jobs assigned to Intels then new design office and laboratory in Haifa, Israel. Later followed the 80C88, a fully static CHMOS design, which could operate with clock speeds from 0 to 8 MHz, there were also several other, more or less similar, variants from other manufacturers. For instance, the NEC V20 was a pin compatible and slightly faster variant of the 8088, successive NEC8088 compatible processors would run at up to 16 MHz. In 1984, Commodore International signed a deal to manufacture the 8088 for use in a licensed Dynalogic Hyperion clone, when announced, the list price of the 8088 was US $124.80. The 8088 is architecturally similar to the 8086. The main difference is there are only 8 data lines instead of the 8086s 16 lines. All of the pins of the device perform the same function as they do with the 8086 with two exceptions. First, pin 34 is no longer BHE, instead it outputs a maximum mode status, SSO. Combined with the IO/M and DT/R signals, the bus cycles can be decoded, the second change is the pin that signals if a memory access or input/output access is being made has had it sense reversed. The pin on the 8088 is IO/M, on the 8086 part it is IO/M. The reason for the reversal is that it makes the 8088 compatible with the 8085. 33–1 million instructions per second. The speed of the unit and the bus of the 8086 CPU was well balanced, with a typical instruction mix. Cutting down the bus to 8 bits made it a bottleneck in the 8088. With the speed of instruction fetch reduced by 50% in the 8088 as compared to the 8086, when the queue is empty, instructions take as long to complete as they take to fetch
21.
Hertz
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The hertz is the unit of frequency in the International System of Units and is defined as one cycle per second. It is named for Heinrich Rudolf Hertz, the first person to provide proof of the existence of electromagnetic waves. Hertz are commonly expressed in SI multiples kilohertz, megahertz, gigahertz, kilo means thousand, mega meaning million, giga meaning billion and tera for trillion. Some of the units most common uses are in the description of waves and musical tones, particularly those used in radio-. It is also used to describe the speeds at which computers, the hertz is equivalent to cycles per second, i. e. 1/second or s −1. In English, hertz is also used as the plural form, as an SI unit, Hz can be prefixed, commonly used multiples are kHz, MHz, GHz and THz. One hertz simply means one cycle per second,100 Hz means one hundred cycles per second, and so on. The unit may be applied to any periodic event—for example, a clock might be said to tick at 1 Hz, the rate of aperiodic or stochastic events occur is expressed in reciprocal second or inverse second in general or, the specific case of radioactive decay, becquerels. Whereas 1 Hz is 1 cycle per second,1 Bq is 1 aperiodic radionuclide event per second, the conversion between a frequency f measured in hertz and an angular velocity ω measured in radians per second is ω =2 π f and f = ω2 π. This SI unit is named after Heinrich Hertz, as with every International System of Units unit named for a person, the first letter of its symbol is upper case. Note that degree Celsius conforms to this rule because the d is lowercase. — Based on The International System of Units, the hertz is named after the German physicist Heinrich Hertz, who made important scientific contributions to the study of electromagnetism. The name was established by the International Electrotechnical Commission in 1930, the term cycles per second was largely replaced by hertz by the 1970s. One hobby magazine, Electronics Illustrated, declared their intention to stick with the traditional kc. Mc. etc. units, sound is a traveling longitudinal wave which is an oscillation of pressure. Humans perceive frequency of waves as pitch. Each musical note corresponds to a frequency which can be measured in hertz. An infants ear is able to perceive frequencies ranging from 20 Hz to 20,000 Hz, the range of ultrasound, infrasound and other physical vibrations such as molecular and atomic vibrations extends from a few femtoHz into the terahertz range and beyond. Electromagnetic radiation is described by its frequency—the number of oscillations of the perpendicular electric and magnetic fields per second—expressed in hertz. Radio frequency radiation is measured in kilohertz, megahertz, or gigahertz
22.
Intel 8087
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The Intel 8087, announced in 1980, was the first x87 floating-point coprocessor for the 8086 line of microprocessors. The purpose of the 8087 was to speed up computations for floating-point arithmetic, such as addition, subtraction, multiplication, division and it also computed transcendental functions such as exponential, logarithmic or trigonometric calculations, and besides floating-point it could also operate on large binary and decimal integers. The performance enhancements were from approximately 20% to over 500%, depending on the specific application, the 8087 could perform about 50,000 FLOPS using around 2.4 watts. The 8087 was an advanced IC for its time, pushing the limits of period manufacturing technology, the sales of the 8087 received a significant boost when IBM included a coprocessor socket on the IBM PC motherboard. Due to a shortage of chips, IBM did not actually offer the 8087 as an option for the PC until it had been on the market for six months, development of the 8087 led to the IEEE 754-1985 standard for floating-point arithmetic. There were later x87 coprocessors for the 80186,80286,80386, starting with the 80486, the later Intel x86 processors did not use a separate floating point coprocessor, floating point functions were provided integrated with the processor. Intel had previously manufactured the 8231 Arithmetic processing unit, and the 8232 Floating Point Processor and these were designed for use with 8080 or similar processors and used an 8-bit data bus. They were interfaced to a host system either through programmed I/O or a DMA controller, the 8087 was initially conceived by Bill Pohlman, the engineering manager at Intel who oversaw the development of the 8086 chip. Bill took steps to be sure that the 8086 chip could support a yet-to-be-developed math chip, in 1977 Pohlman got the go ahead to design the 8087 math chip. Bruce Ravenel was assigned as architect, and John Palmer was hired to be co-architect, Palmer credited William Kahans writings on floating point as a significant influence on their design. The 8087 design initially met a cool reception in Santa Clara due to its aggressive design, eventually, the design was assigned to Intel Israel, and Rafi Nave was assigned to lead the implementation of the chip. Palmer, Ravenel and Nave were awarded patents for the design, robert Koehler and John Bayliss were also awarded a patent for the technique where some instructions with a particular bit pattern were offloaded to the coprocessor. The 8087 had 45,000 transistors and was manufactured as a 3 μm depletion load HMOS circuit and it worked in tandem with the 8086 or 8088 and introduced about 60 new instructions. Most 8087 assembly mnemonics begin with F, such as FADD, FMUL, FCOM and so on, the instruction mnemonic assigned by Intel for these coprocessor instructions is ESC. For an 8087 instruction with a memory operand, if the called for the operand to be read. The WAIT instruction was provided for this purpose, and most assemblers implicitly asserted a WAIT instruction before each instance of most floating-point coprocessor instructions. The WAIT instruction waited for the input pin of the 8086/8088 to be asserted. The 8086 and 8088 have two queue status signals which are connected to the coprocessor to allow it to synchronize with the CPUs internal timing of execution of instructions from its prefetch queue
23.
Floating-point unit
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A floating-point unit is a part of a computer system specially designed to carry out operations on floating point numbers. Typical operations are addition, subtraction, multiplication, division, square root, some systems can also perform various transcendental functions such as exponential or trigonometric calculations, though in most modern processors these are done with software library routines. This could be an integrated circuit, an entire circuit board or a cabinet. Where floating-point calculation hardware has not been provided, floating point calculations are done in software, emulation can be implemented on any of several levels, in the CPU as microcode, as an operating system function, or in user space code. When only integer functionality is available the CORDIC floating point emulation methods are most commonly used, in most modern computer architectures, there is some division of floating-point operations from integer operations. This division varies significantly by architecture, some, like the Intel x86 have dedicated floating-point registers, in earlier superscalar architectures without general out-of-order execution, floating-point operations were sometimes pipelined separately from integer operations. Since the early 1990s, many microprocessors for desktops and servers have more than one FPU, the modular architecture of Bulldozer microarchitecture uses a special FPU named FlexFPU, which uses simultaneous multithreading. Each physical integer core, two per module, is threaded, in contrast with Intels Hyperthreading, where two virtual simultaneous threads share the resources of a single physical core. Some floating-point hardware only supports the simplest operations - addition, subtraction, but even the most complex floating-point hardware has a finite number of operations it can support - for example, none of them directly support arbitrary-precision arithmetic. When a CPU is executing a program calls for a floating-point operation that is not directly supported by the hardware. In systems without any floating-point hardware, the CPU emulates it using a series of simpler fixed-point arithmetic operations that run on the arithmetic logic unit. The software that lists the series of operations to emulate floating-point operations is often packaged in a floating-point library. In some cases, FPUs may be specialized, and divided between simpler floating-point operations and more complicated operations, like division, in some cases, only the simple operations may be implemented in hardware or microcode, while the more complex operations are implemented as software. In the 1980s, it was common in IBM PC/compatible microcomputers for the FPU to be separate from the CPU. It would only be purchased if needed to speed up or enable math-intensive programs, the IBM PC, XT, and most compatibles based on the 8088 or 8086 had a socket for the optional 8087 coprocessor. Other companies manufactured co-processors for the Intel x86 series, coprocessors were available for the Motorola 68000 family, the 68881 and 68882. These were common in Motorola 68020/68030-based workstations like the Sun 3 series, there are also add-on FPUs coprocessor units for microcontroller units /single-board computer, which serve to provide floating-point arithmetic capability. These add-on FPUs are host-processor-independent, possess their own programming requirements and are provided with their own integrated development environments
24.
Industry Standard Architecture
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Industry Standard Architecture is a retronym term for the 16-bit internal bus of IBM PC/AT and similar computers based on the Intel 80286 and its immediate successors during the 1980s. The bus was backward compatible with the 8-bit bus of the 8088-based IBM PC, originally referred to as the PC/AT-bus it was also termed I/O Channel by IBM. The 16-bit ISA bus was used with 32-bit processors for several years. An attempt to extend it to 32 bits, called Extended Industry Standard Architecture, was not very successful, later buses such as VESA Local Bus and PCI were used instead, often along with ISA slots on the same mainboard. Derivatives of the AT bus structure were and still are used in ATA/IDE, the PCMCIA standard, Compact Flash, the PC/104 bus, compaq created the term Industry Standard Architecture to replace PC compatible. The ISA bus was developed by a led by Mark Dean at IBM as part of the IBM PC project in 1981. It originated as an 8-bit system, the newer 16-bit standard, the IBM AT bus, was introduced in 1984. Therefore, the ISA bus was synchronous with the CPU clock, designed to connect peripheral cards to the motherboard, ISA allows for bus mastering although only the first 16 MB of main memory are available for direct access. The 8-bit bus ran at 4.77 MHz, while the 16-bit bus operated at 6 or 8 MHz IBM RT/PC also used the 16-bit bus. It was also available on some non-IBM compatible machines such as Motorola 68k-based Apollo and Amiga 3000 workstations, the short-lived AT&T Hobbit and later PowerPC based BeBox. MCA had many features that would appear in PCI, the successor of ISA. The system was far more advanced than the AT bus, and computer manufacturers responded with the Extended Industry Standard Architecture and later, in fact, VLB used some electronic parts originally intended for MCA because component manufacturers already were equipped to manufacture them. Both EISA and VLB were backwards-compatible expansions of the AT bus, users of ISA-based machines had to know special information about the hardware they were adding to the system. While a handful of devices were essentially plug-n-play, this was rare, users frequently had to configure several parameters when adding a new device, such as the IRQ line, I/O address, or DMA channel. MCA had done away with this complication, and PCI actually incorporated many of the ideas first explored with MCA, in reality, ISA PnP can be troublesome, and did not become well-supported until the architecture was in its final days. PCI slots were the first physically incompatible expansion ports to directly squeeze ISA off the motherboard, at first, motherboards were largely ISA, including a few PCI slots. By the mid-1990s, the two types were roughly balanced, and ISA slots soon were in the minority of consumer systems. Which was why the software compatible LPC bus was created, in late 2008, even floppy disk drives and serial ports were disappearing, and the extinction of vestigial ISA from chipsets was on the horizon
25.
Video card
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A video card is an expansion card which generates a feed of output images to a display. Frequently, these are advertised as discrete or dedicated graphics cards, Standards such as MDA, CGA, HGC, Tandy, PGC, EGA, VGA, MCGA,8514 or XGA were introduced from 1982 to 1990 and supported by a variety of hardware manufacturers. The majority of video cards are built with either AMD-sourced or Nvidia-sourced graphics chips. Until 2000, 3dfx Interactive was also an important, and often groundbreaking, most video cards offer various functions such as accelerated rendering of 3D scenes and 2D graphics, MPEG-2/MPEG-4 decoding, TV output, or the ability to connect multiple monitors. Video cards also have sound capabilities to output sound – along with the video for connected TVs or monitors with integrated speakers. Graphics cards werent very useful for computers, since they didnt have the capability to run graphic-based games or high-resolution videos as modern computers do now. Within the industry, video cards are sometimes called graphics add-in-boards, abbreviated as AIBs, as an alternative to the use of a video card, video hardware can be integrated into the motherboard or the CPU. Both approaches can be called integrated graphics, motherboard-based implementations are sometimes called on-board video while CPU-based implementations are known as accelerated processing units. The ability to disable the integrated graphics sometimes also allows the use of a motherboard on which the on-board video has failed. Sometimes both the graphics and a dedicated graphics card can be used simultaneously to feed separate displays. The main advantages of integrated graphics include cost, compactness, simplicity, the performance disadvantage of integrated graphics arises because the graphics processor shares system resources with the CPU. A dedicated graphics card has its own random access memory, its own cooling system, upgrading to a dedicated graphics card offloads work from the CPU and system RAM, so not only will graphics processing be faster, but the computers overall performance may also improve. Both of the dominant CPU makers, AMD and Intel, are moving to APUs, as of late 2013, the best APUs provide graphics processing approaching mid-range mobile video cards and are adequate for casual gaming. Users seeking the highest video performance for gaming or other graphics-intensive uses should still choose computers with dedicated graphics cards. Beyond the enthusiast segment is the market for video cards for workstations used in the special effects industry. Nvidia is a player in the professional segment. As the processing power of cards has increased, so has their demand for electrical power. Current high-performance video cards tend to consume a great deal of power, for example, the thermal design power for the GeForce GTX TITAN is 250 Watts
26.
IBM Monochrome Display Adapter
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The Monochrome Display Adapter is IBMs standard video display card and computer display standard for the PC introduced in 1981. The MDA did not have any pixel-addressable graphics modes and it had only a single monochrome text mode, which could display 80 columns by 25 lines of high resolution text characters or symbols useful for drawing forms. Based on the IBM Datamasters display system, the standard IBM MDA card was equipped with four kilobytes of video memory. The MDAs high character resolution was a feature meant to facilitate business and wordprocessing use, Each character was rendered in a box of 9×14 pixels, some characters, such as the lowercase m, were rendered eight pixels across. The theoretical total screen display resolution of the MDA was 720×350 pixels and this number is arrived at through calculating character width by columns of text and character height by rows of text. However, the MDA again could not address individual pixels, it could work in text mode. The character patterns were stored in ROM on the card and the set could not be changed from the hardware code page 437. The only way to simulate graphical screen content was through ASCII art, because of the lack of pixel-addressable graphics, MDA owners could not play most graphics-based games. At least one game, IBMs One Hundred And One Monochrome Mazes, code page 437 included the standard 127 ASCII characters but also another 127 characters like the aforementioned characters for drawing forms. Some of these shapes would later show up in Unicode as box-drawing characters, the characters were also used in early PC games such as early BBS door games, or games like Castle Adventure by Kevin Bales. IBMs original MDA included a printer port, thus avoiding the need for a separate parallel interface on computers fitted with an MDA. The registers also allow the monochrome mode to be set on, yet there was no software to actually control that feature. Other boards offered MDA compatibility, although with differences on how attributes are displayed or the font used, PC Magazine reported in June 1983 that while the IBM monochrome display is absolutely beautiful for text and wonderfully easy on the eyes, but is limited to simple character graphics. Text quality on displays connected to the color/graphics adapter. is at best of medium quality and is conducive to eyestrain over the long haul, introduced in 1982, the non-IBM Hercules Graphics Card offered both an MDA compatible high resolution text mode and a monochrome graphics mode. It could address individual pixels and display a black and white picture of 720×348 pixels and this resolution was better than even the highest monochrome resolution CGA cards could offer. Thus, even without a color capability of any kind, the Hercules adapters offer of monochrome graphics without sacrificing MDA-equivalent text quality made it a desirable choice for many. Adapters exist to convert MDA into VGA for upgrading to LCD, using a GBS-8219 with the video signal and the horizontal sync and vertical sync, set to a RGB, and Sync Separate
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Color Graphics Adapter
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For this reason, it also became that computers first color computer display standard. Built around the Motorola MC6845 display controller, the CGA card featured several graphics, the highest display resolution of any mode was 640×200, and the highest color depth supported was 4-bit. CGA supports, 320×200 in 4 colors from a 16 color hardware palette, the 40×25 text and 320×200 graphics modes are usable with a television, and the 80×25 text and 640×200 graphics modes are intended for a monitor. Despite varying bit depths among the CGA graphics modes, CGA processes colors in its palette in four bits, in graphics modes, colors are set per-pixel, in text modes, colors are set per-character, with an independent foreground and background color for each character. These four bits are passed on unmodified to the DE-9 connector at the back of the card, leaving all color processing to the RGBI monitor connected to it. With respect to the RGBI color model described above, the monitor would use approximately the following formula to process the digital four-bit color number to analog voltages ranging from 0.0 to 1. For the composite output, these four-bit color numbers are encoded by the CGAs onboard hardware into an NTSC-compatible signal fed to the cards RCA output jack. For cost reasons, this is not done using an RGB-to-YIQ converter as called for by the NTSC standard, consequently, the hues seen are lacking in purity, notably, both cyan and yellow have a greenish tint, and color 6 again looks dark yellow instead of brown. When the CGA was introduced in 1981, IBM did not offer an RGBI monitor, instead, customers were supposed to use the RCA output with an RF modulator to connect the CGA to their television set. The IBM5153 Personal Computer Color Display would not be introduced until March 1983 and this is relevant insofar as if an application or game programmer used either one of these configurations, they will have expected color 6 to look dark yellow instead of brown. CGA offers four BIOS text modes, 40×25 characters in up to 16 colors, each character is a pattern of 8×8 dots. The effective screen resolution in this mode is 320×200 pixels, though individual pixels cannot be addressed independently, the choice of patterns for any location is thus limited to one of the 256 available characters, the patterns for which are stored in a ROM chip on the card itself. The display font in text mode is fixed and cannot be changed. The card has sufficient video RAM for eight different text pages in this mode, BIOS Modes 0 &1 select 40 column text modes. The difference between two modes can only be seen on a composite monitor, mode 0 disables the color burst. Mode 1 enables the color burst, allowing for color, Mode 0 and Mode 1 are functionally identical on RGB monitors and on later adapters that emulate CGA without supporting composite color output. 80×25 characters in up to 16 colors, each character is again an 8×8 dot pattern, in a pixel aspect ratio of 1,2.4. The effective screen resolution of this mode is 640×200 pixels, again, the pixels cannot be individually addressed
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Enhanced Graphics Adapter
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EGA was introduced in October 1984 by IBM, shortly after its new PC/AT. The EGA standard was made obsolete by the introduction in 1987 of MCGA and VGA with the PS/2 computer line, shortly before the introduction of VGA, Genoa Systems introduced a half-size graphics card built around a proprietary chip set, which they called Super EGA. EGA produces a display of sixteen simultaneous colors from a palette of sixty-four, EGA also includes full sixteen-color versions of the CGA 640×200 and 320×200 graphics modes, only the sixteen CGA/RGBI colors are available in these modes. EGA is dual-sync, it scans at 21.8 kHz when 350-line modes are used and 15.7 kHz when 200-line modes are used, the original CGA modes are also present, though EGA is not 100% hardware compatible with CGA. EGA can drive an MDA monitor by a setting of switches on the board, only 640×350 high-resolution monochrome graphics. EGA cards use the PC ISA bus and were starting in both eight- and sixteen-bit versions. The original IBM EGA card had 64 KB of onboard RAM, all third-party cards came with 128 KB already installed and some even 256 KB, allowing multiple graphics pages. A few third-party EGA clones feature a range of extended graphics modes, as well as automatic monitor type detection, EGA supports, 640×350 w/16 colors, pixel aspect ratio of 1,1.37. 640×350 w/2 colors, pixel aspect ratio of 1,1.37, 640×200 w/16 colors, pixel aspect ratio of 1,2.4. 320×200 w/16 colors, pixel aspect ratio of 1,1.2 and this also allows the CGAs alternate brown color to be used without any additional display hardware. The later VGA standard built on this by allowing each of the 64 colors to be further customized, the extended color palette cannot be used in 200-line modes. When selecting a color from the EGA palette, two bits are used for the red, green and blue channels and this allows each channel a value of 0,1,2 or 3. To select the color magenta, the red and blue values would be medium intensity, for magenta, the most significant bit in the red and blue values is a 1, so the uppercase R and B placeholders would become 1. All other digits are zeros, giving the binary number 000101 for the color magenta and this is 5 in decimal, so setting a palette entry to 5 would result in it being set to magenta. All the color values for the colors are listed in the table on the right. The EGA uses a female nine-pin D-subminiature connector which looks identical to the CGA connector, the hardware signal interface, including the pin configuration, is largely compatible with CGA. Similarly, if the CGA monitor is wired with pin two as its ground, it will not work with the EGA, though it will work with a CGA. Almost all EGA cards have DIP switches on the back of the card to select the monitor type, if CGA is selected, the card will operate in 200-line mode and use 8x8 characters in text mode
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Professional Graphics Controller
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Professional Graphics Controller is a graphics card manufactured by IBM for PCs. It consists of three interconnected PCBs, and contains its own processor and memory, the PGC was, at the time of its release, the most advanced graphics card for the IBM XT and aimed for tasks such as CAD. It was intended for the design market and included 320 kB of display RAM. The 8088 was placed directly on the card to permit rapid updates of video memory, other cards forced the PCs CPU to write to video memory through a slower ISA bus. While never widespread in consumer-class personal computers, its US $4,290 list price compared favorably to US$50,000 dedicated CAD workstations of the time and it was discontinued in 1987 with the arrival of VGA and 8514. The board was targeted at the CAD market, therefore a limited support is to be expected. Yet, the software known to support the PGC are IBMs Graphical Kernel System, P-CAD4.5, Canyon State Systems CompuShow. PGC supports, 640x480 with 256 colors from a palette of 4096 Color Graphics Adapter text, text modes use EGA 14-pixel font and have 400 rows of pixels. The display adapter was composed of three physical circuit boards and occupied two adjacent expansion slots on the XT or AT motherboard, the card was located in between the two slots. The PGC could not be used in the original IBM PC without modification due to the different spacing of its slots. In addition to its native 640 x 480 mode, the PGC optionally supported the text and graphics modes of the Color Graphics Adapter. However, it was only partly register-compatible with CGA, the PGCs matching display was the IBM5175, an analog RGB monitor that is unique to it and not compatible with any other video card without modification. With hardware modification, the 5175 can be used with VGA, Macintosh, some surplus 5175s in VGA-converted form were still sold by catalog retailers such as COMB as late as the early 1990s
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IBM PC DOS
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IBM PC DOS is a discontinued operating system for the IBM Personal Computer, manufactured and sold by IBM from the 1981 into the 2000s. Before version 6.1, PC DOS was an IBM-branded version of MS-DOS, from version 6.1 on, PC DOS became IBMs independent product. The IBM task force assembled to develop the PC decided that critical components of the machine, including the operating system and this radical break from company tradition of in-house development was one of the key decisions that made the IBM PC an industry standard. At that time private company Microsoft, founded five years before by Bill Gates, was selected for the operating system. IBM wanted Microsoft to retain ownership of whatever software it developed, according to task force member Jack Sams, The reasons were internal. We had a problem being sued by people claiming we had stolen their stuff. It could be expensive for us to have our programmers look at code that belonged to someone else because they would then come back and say we stole it. We had lost a series of suits on this, and so we didnt want to have a product which was clearly someone elses product worked on by IBM people and we went to Microsoft on the proposition that we wanted this to be their product. IBM first contacted Microsoft to look the company over in July 1980, negotiations continued over the next months, and the paperwork was officially signed in early November. Although IBM expected that most customers would use PC DOS, The IBM PC also supported CP/M-86, which became available six months after PC DOS, and UCSD p-System operating systems. IBMs expectation proved correct, one found that 96. 3% of PCs were ordered with the $40 PC-DOS compared to 3. 4% for the $240 CP/M-86. Microsoft first licensed, then purchased 86-DOS from Seattle Computer Products, ORear got 86-DOS to run on the prototype PC in February 1981. 86-DOS had to be converted from 8-inch to 5. 25-inch floppy disks and integrated with the BIOS, IBM had more people writing requirements for the computer than Microsoft had writing code. ORear often felt overwhelmed by the number of people he had to deal with at the ESD facility in Boca Raton, 86-DOS was rebranded IBM PC DOS1.0 for its August 1981 release with the IBM PC. The initial version of DOS was largely based on CP/M-801. x and most of its architecture, function calls, the most significant difference was the fact that it introduced a different file system, FAT12. Unlike all later DOS versions, the DATE and TIME commands were separate rather than part of COMMAND. COM. Single-sided 160 kilobyte 5.25 floppies were the only disk format supported, in late 1981 Paterson, now at Microsoft, began writing PC DOS1.10. It debuted in May 1982 along with the Revision B IBM PC, support for the new double-sided drives was added, allowing 320 kB per disk
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IBM BASIC
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The IBM Personal Computer Basic, commonly shortened to IBM BASIC, is a programming language first released by IBM with the IBM Personal Computer in 1981. IBM released four different versions of the Microsoft BASIC interpreter, licensed from Microsoft for the PC and they are known as Cassette BASIC, Disk BASIC, Advanced BASIC, and Cartridge BASIC. Versions of Disk BASIC and Advanced BASIC were included with IBM PC DOS up to PC DOS4, in addition to the features of an ANSI standard BASIC, the IBM versions offered support for the graphics and sound hardware of the IBM PC line. Source code could be typed in with a screen editor. IBM also released a version of the Microsoft BASIC compiler for the PC, IBM licensed Microsoft BASIC for the PC despite already having its own version for the companys mainframes. Don Estridge said, Microsoft BASIC had hundreds of thousands of users around the world, how are you going to argue with that. IBM Cassette BASIC came in 32 kilobytes of memory, separate from the 8 KB BIOS ROM of the original IBM PC. Cassette BASIC provided the user interface if there was no floppy disk drive installed. The name Cassette BASIC came from its use of cassette tapes rather than floppy disks to store programs, Cassette BASIC was built into the ROMs of the original PC and XT, and early models in the PS/2 line. It only supported loading and saving programs to the IBM cassette tape interface, the entry-level version of the 5150 came with just 16 KB of random-access memory, which was sufficient to run Cassette BASIC. There were three versions of Cassette BASIC, C1.00, C1.10, and C1.20, IBM Disk BASIC was included in the original IBM PC DOS and required 32 KB of RAM. Because it uses the 32 KB Cassette BASIC ROM, BASIC. COM did not run on even highly compatible PC clones such as the Compaq Portable, the name Disk BASIC came from its use of floppy disks rather than cassette tapes to store programs and data. Disk-based code corrected errata in the ROM-resident code and added floppy disk, Disk BASIC could be identified by its use of the letter D preceding the version number. It added disk support and some features lacking in Cassette BASIC, the primary purpose of Disk BASIC was as a lite version for IBM PCs with only 64k of memory. By 1986, all new PCs shipped with at least 256k, IBM Advanced BASIC was also included in the original IBM PC DOS, and required 48 KB of RAM and the ROM-resident code of Cassette BASIC. BASICA would not run on computers or later IBM models. BASICA versions were the same as their respective DOS, beginning with v1.00, the early versions of BASICA did not support subdirectories and some graphics commands functioned slightly differently. BASIC1. xs PAINT command also makes use of the stack for storage
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Read-only memory
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Read-only memory is a type of non-volatile memory used in computers and other electronic devices. Data stored in ROM can only be modified slowly, with difficulty, or not at all, strictly, read-only memory refers to memory that is hard-wired, such as diode matrix and the later mask ROM, which cannot be changed after manufacture. Although discrete circuits can be altered in principle, integrated circuits cannot and that such memory can never be changed is a disadvantage in many applications, as bugs and security issues cannot be fixed, and new features cannot be added. More recently, ROM has come to include memory that is read-only in normal operation, the simplest type of solid-state ROM is as old as the semiconductor technology itself. Combinational logic gates can be joined manually to map n-bit address input onto arbitrary values of m-bit data output, with the invention of the integrated circuit came mask ROM. In mask ROM, the data is encoded in the circuit. This leads to a number of disadvantages, It is only economical to buy mask ROM in large quantities. The turnaround time between completing the design for a mask ROM and receiving the finished product is long, for the same reason, mask ROM is impractical for R&D work since designers frequently need to modify the contents of memory as they refine a design. If a product is shipped with faulty mask ROM, the way to fix it is to recall the product. Subsequent developments have addressed these shortcomings, PROM, invented in 1956, allowed users to program its contents exactly once by physically altering its structure with the application of high-voltage pulses. This addressed problems 1 and 2 above, since a company can order a large batch of fresh PROM chips. The 1971 invention of EPROM essentially solved problem 3, since EPROM can be reset to its unprogrammed state by exposure to strong ultraviolet light. All of these technologies improved the flexibility of ROM, but at a significant cost-per-chip, rewriteable technologies were envisioned as replacements for mask ROM. The most recent development is NAND flash, also invented at Toshiba, as of 2007, NAND has partially achieved this goal by offering throughput comparable to hard disks, higher tolerance of physical shock, extreme miniaturization, and much lower power consumption. Every stored-program computer may use a form of storage to store the initial program that runs when the computer is powered on or otherwise begins execution. Likewise, every non-trivial computer needs some form of memory to record changes in its state as it executes. Forms of read-only memory were employed as non-volatile storage for programs in most early stored-program computers, consequently, ROM could be implemented at a lower cost-per-bit than RAM for many years. Most home computers of the 1980s stored a BASIC interpreter or operating system in ROM as other forms of storage such as magnetic disk drives were too costly
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IBM Personal System/2
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The Personal System/2 or PS/2 was IBMs third generation of personal computers. Released in 1987, it replaced the IBM PC, XT, AT. The PS/2 line was created by IBM in an attempt to control of the PC market by introducing an advanced yet proprietary architecture. IBMs considerable market presence plus the reliability of the PS/2 ensured that the systems would sell in large numbers. Also the evolving Wintel architecture was seeing a period of dramatic reductions in price, the OS/2 operating system was announced at the same time as the PS/2 line and was intended to be the primary operating system for models with Intel 286 or later processors. However, at the time of the first shipments, only PC DOS was available, OS/21.0 and Microsofts Windows 2.0 became available several months later. IBM also released AIX PS/2, a UNIX operating system for PS/2 models with Intel 386 or later processors, for years before IBM released the PS/2, rumors spread about IBMs plans for successors to its IBM PC, XT, and AT personal computers. Among the rumors that did not come true, The company would use proprietary, the company would release a version of its VM mainframe operating system for them. The company would design the new computers to make third-party communications products more difficult to design, IBMs PS/2 was designed to remain software compatible with their PC/AT/XT line of computers upon which the large PC clone market was built, but the hardware was quite different. CBIOS was so compatible that it even included Cassette BASIC, while IBM did not publish the BIOS source code, it did promise to publish BIOS entry points. With the IBM PS/2 line, Micro Channel Architecture was also introduced, MCA was conceptually similar to the channel architecture of the IBM System/360 mainframes. MCA was technically superior to ISA and allowed for higher speed communications within the system, MCA featured many advances not seen in other standards until several years later. Transfer speeds were on par with the much later PCI standard, MCA allowed one-to-one, card to card, and multi-card to processor simultaneous transaction management which is a feature of the PCI-X bus format. Bus mastering capability, bus arbitration, and a form of plug-and-play BIOS management of hardware were all benefits of MCA. (One book from the year 2000 writes, MCA used a version of what we know now as “Plug-N′-Play”, requiring a special setup disk for each machine. MCA never gained wide acceptance outside of the PS/2 line due to IBMs anti-clone practices and incompatibilities with ISA, IBM offered to sell an MCA license to anyone who could afford the royalty. However, royalties were required for every MCA-compatible machine sold and a payment for every IBM-compatible machine the particular maker had made in the past, there was nothing unique in IBM insisting on payment of royalties on the use of its patents applied to Micro Channel based machines. However, up until that time, some companies had failed to pay IBM for the use of its patents on the generation of Personal Computer
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IBM System/370
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The IBM System/370 was a model range of IBM mainframe computers announced on June 30,1970 as the successors to the System/360 family. A Dynamic Address Translation option was not announced until 1972, 128-bit floating point arithmetic on all models, the original System/370 line underwent several architectural improvements during its roughly 20-year lifetime. The first System/370 machines, the Model 155, the Model 165, and these changes included,13 new instructions, among which were MOVE LONG, COMPARE LOGICAL LONG, thereby permitting operations on up to 2^24-1 bytes, vs. They did not include support for virtual memory, in 1972, a very significant change was made when support for virtual memory was introduced with IBMs System/370 Advanced Function announcement. IBM had initially chosen to exclude virtual storage from the S/370 line, the S/370-145 had an associative memory used by the microcode for the DOS compatibility feature from its first shipments in June 1971, the same hardware was used by the microcode for DAT. The 145 microcode architecture simplified the addition of virtual memory, allowing this capability to be present in early 145s without the extensive modifications needed in other models. The Reference and Change bits of the Storage-protection Keys, however, were labeled on the rollers, existing S/370-145 customers were happy to learn that they did not have to purchase a hardware upgrade in order to run DOS/VS or OS/VS1. After installation, these models were known as the S/370-155-II and S/370-165-II, IBM wanted customers to upgrade their 155 and 165 systems to the widely sold S/370-158 and -168. This led to the original S/370-155 and S/370-165 models being described as boat anchors, later architectural changes primarily involved expansions in memory – both physical memory and virtual address space – to enable larger workloads and meet client demands for more storage. This was the trend as Moores Law eroded the unit cost of memory. As with all IBM mainframe development, preserving backward compatibility was paramount, in October 1981, the 3033 and 3081 processors added extended real addressing, which allowed 26-bit addressing for physical storage. This capability appeared later on other systems, such as the 4381 and 3090, the cross-memory services capability which facilitated movement of data between address spaces was actually available just prior to S/370-XA architecture on the 3031,3032 and 3033 processors. As described above, the S/370 product line underwent a major architectural change, the evolution of S/370 addressing was always complicated by the basic S/360 instruction set design, and its large installed code base, which relied on a 24-bit logical address. Most shops thus continued to run their 24-bit applications in a higher-performance 31-bit world and this evolutionary implementation had the characteristic of solving the most urgent problems first, relief for real memory addressing being needed sooner than virtual memory addressing. IBMs choice of 31-bit addressing for 370-XA involved various factors, the System/360 Model 67 had included a full 32-bit addressing mode, but this feature was not carried forward to the System/370 series, which began with only 24-bit addressing. When IBM later expanded the S/370 address space in S/370-XA, several reasons are cited for the choice of 31 bits, in particular, the standard subroutine calling convention marked the final parameter word by setting its high bit. Interaction between 32-bit addresses and two instructions that treated their arguments as signed numbers, input from key initial Model 67 sites, which had debated the alternatives during the initial system design period, and had recommended 31 bits. The following table summarizes the major S/370 series and models, the second column lists the principal architecture associated with each series
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Schematic
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A schematic, or schematic diagram, is a representation of the elements of a system using abstract, graphic symbols rather than realistic pictures. A schematic usually omits all details that are not relevant to the information the schematic is intended to convey, in an electronic circuit diagram, the layout of the symbols may not resemble the layout in the circuit. In the schematic diagram, the elements are arranged to be more easily interpreted by the viewer. Schematics and other types of diagrams, e. g, a semi-schematic diagram combines some of the abstraction of a purely schematic diagram with other elements displayed as realistically as possible, for various reasons. It is a compromise between an abstract diagram and an exclusively realistic representation. In electrical and electronic industry, a diagram is often used to describe the design of equipment. Schematic diagrams are used for the maintenance and repair of electronic. Original schematics were done by hand, using standardized templates or pre-printed adhesive symbols, in electronic design automation, until the 1980s schematics were virtually the only formal representation for circuits. For example, hardware description languages are indispensable for modern digital circuit design, schematics for electronic circuits are prepared by designers using EDA tools called schematic capture tools or schematic entry tools. These tools go beyond simple drawing of devices and connections, usually they are integrated into the whole IC design flow and linked to other EDA tools for verification and simulation of the circuit under design. In electric power systems design, a drawing called a one-line diagram is frequently used to represent substations. These diagrams simplify and compress the details that would be repeated on each phase of a three-phase system, electrical diagrams for switchgear often have common device functions designate by standard function numbers. Many automotive and motorcycle repair manuals devote a significant number of pages to schematic diagrams, energy Systems Language Chart Diagram Straight-line diagram Topological map Transit map
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BIOS
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The BIOS is a type of firmware used to perform hardware initialization during the booting process on IBM PC compatible computers, and to provide runtime services for operating systems and programs. The BIOS firmware is built into personal computers, and it is the first software they run when powered on, the name itself originates from the Basic Input/Output System used in the CP/M operating system in 1975. Originally proprietary to the IBM PC, the BIOS has been engineered by companies looking to create compatible systems. The fundamental purposes of the BIOS in modern PCs are to initialize and test the hardware components. Variations in the hardware are hidden by the BIOS from programs that use BIOS services instead of directly accessing the hardware. MS-DOS, which was the dominant PC operating system from the early 1980s until the mid-1990s, relied on BIOS services for disk, keyboard, and text display functions. Most BIOS implementations are specifically designed to work with a computer or motherboard model. This allows easy updates to the BIOS firmware so new features can be added or bugs can be fixed, unified Extensible Firmware Interface was designed as a successor to BIOS, aiming to address its technical shortcomings. As of 2014, new PC hardware predominantly ships with UEFI firmware, together with the underlying hardware-specific, but operating system-independent System BIOS, which resides in ROM, it represents the analogous to the CP/M BIOS. With the introduction of PS/2 machines, IBM divided the System BIOS into real-mode, the BIOS of the original IBM PC XT had no interactive user interface. Options on the IBM PC and XT were set by switches and jumpers on the main board, starting around the mid-1990s, it became typical for the BIOS ROM to include a BIOS configuration utility or BIOS setup utility, accessed at system power-up by a particular key sequence. This program allowed the user to set configuration options, of the type formerly set using DIP switches. The disk was supplied with the computer, and if it was lost the settings could not be changed. Instead of battery-backed RAM, the modern Wintel machine may store the BIOS configuration settings in flash ROM, early Intel processors started at physical address 000FFFF0h. When a modern x86 microprocessor is reset, it starts in pseudo 16-bit real mode, the code segment register is initialized with selector F000h, base FFFF0000h, and limit FFFFh, so that execution starts at 4 GB minus 16 bytes. The platform logic maps this address into the system ROM, mirroring address 000FFFF0h, if the system has just been powered up or the reset button was pressed, the full power-on self-test is run. This saves the time used to detect and test all memory. If the download was apparently successful, the BIOS would verify a checksum on it and then run it
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Intel 80286
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The Intel 80286 is a 16-bit microprocessor that was introduced on 1 February 1982. It was the first 8086 based CPU with separate, non-multiplexed, address and data buses and also the first with memory management, the 80286 was employed for the IBM PC/AT, introduced in 1984, and then widely used in most PC/AT compatible computers until the early 1990s. Although now long since obsolete for use in computers,80286 based processors are still widely used in embedded microcontroller applications. Intels first 80286 chips were specified for a maximum clockrate of 4,6 or 8 MHz, AMD and Harris later produced 16 MHz,20 MHz and 25 MHz parts, respectively. Intersil and Fujitsu also designed fully static CMOS versions of Intels original depletion-load nMOS implementation, the 6 MHz,10 MHz and 12 MHz models were reportedly measured to operate at 0.9 MIPS,1.5 MIPS and 2.66 MIPS respectively. The later E-stepping level of the 80286 was free of the several significant errata that caused problems for programmers, the 80286 was designed for multi-user systems with multitasking applications, including communications and real-time process control. It had 134,000 transistors and consisted of four independent units, address unit, bus unit, instruction unit, the significantly increased performance over the 8086 was primarily due to the non-multiplexed address and data buses, more address calculation hardware and a faster multiplier. It was produced in a 68-pin package including PLCC, LCC, the performance increase of the 80286 over the 8086 could be more than 100% per clock cycle in many programs. This was an increase, fully comparable to the speed improvements around a decade later when the i486 or the original Pentium were introduced. This was partly due to the address and data buses. They were performed by a unit in the 80286 while the older 8086 had to do effective address computation using its general ALU. Also, the 80286 was more efficient in the prefetch of instructions, buffering, execution of jumps, together with contemporary 80186,286 added new instructions, ENTER, LEAVE, BOUND, INS, OUTS, PUSHA, POPA, PUSH immediate, IMUL immediate, multi-bit shifts. The intel 80286 had a 24-bit address bus and was able to address up to 16 MB of RAM, however cost and initial rarity of software using the memory above 1 MB meant that 80286 computers were rarely shipped with more than one megabyte of RAM. Additionally, there was a performance penalty involved in accessing extended memory from real mode, the 286 was the first of the x86 CPU family to support protected mode. In addition, it was the first commercially available microprocessor with on-chip MMU capabilities and this would allow IBM compatibles to have advanced multitasking OSes for the first time and compete in the Unix-dominated server/workstation market. Several additional instructions were introduced in protected mode of 80286, which are helpful for multitasking operating systems, another important feature of 80286 is Prevention of Unauthorized Access. This is achieved by, Forming different segments for data, code, and stack, segment with lower privilege level cannot access the segment with higher privilege level. By design, the 286 could not revert from protected mode to the basic 8086-compatible real mode without a hardware-initiated reset, though it worked correctly, the method imposed a huge performance penalty
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SIMM
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A SIMM, or single in-line memory module, is a type of memory module containing random-access memory used in computers from the early 1980s to the late 1990s. It differs from a dual in-line memory module, the most predominant form of memory module today, SIMMs were standardised under the JEDEC JESD-21C standard. Most early PC motherboards used socketed DIP chips for DRAM, as computer memory capacities grew, memory modules were used to save motherboard space and ease memory expansion. Instead of plugging in eight or nine single DIP chips, only one memory module was needed to increase the memory of the computer. SIMMs were invented in 1982 by James J. Parker at Zenith Microcircuits, Wang Laboratories tried to patent it and were granted a patent in April 1987. That patent was later voided when Wang Laboratories sued multiple companies for infringement, the lawsuit was then dropped and the patent was vacated. The original memory modules were built upon ceramic substrates with 64K Hitachi flip chip parts and had pins, later the modules were built on ceramic substrates with Fujitsu plastic J-lead chips and still later, they were made on standard PCB material. SIMMs using pins are usually called SIP or SIPP memory modules to distinguish them from the common modules using edge connectors. The first variant of SIMMs has 30 pins and provides 8 bits of data and they were used in AT-compatible, 386-based, 486-based, Macintosh Plus, Macintosh II, Quadra and Atari STE microcomputers, and Wang VS minicomputers. The second variant of SIMMs has 72 pins and provides 32 bits of data and these appeared first in the early 1990s in the IBM PS/2, and later in systems based on the 486, Pentium, Pentium Pro, early Pentium II, and contemporary/competing chips of other brands. By the mid 90s, 72-pin SIMMs had replaced 30-pin SIMMs in new-build computers, non-IBM PC computers such as UNIX workstations may use proprietary non-standard SIMMs. The Macintosh IIfx uses proprietary non-standard SIMMs with 64 pins, DRAM technologies used in SIMMs include FPM, and the higher-performance EDO DRAM. Due to the data bus widths of the memory modules and some processors. The rule of thumb is a 286, 386SX,68000 or low-end 68020 /68030 system would require two 30-pin SIMMs for a memory bank. On 386DX,486, and full-spec 68020 through 68060 systems, on Pentium systems, two 72-pin SIMMs are required. However, some Pentium systems have support for a half bank mode, conversely, some 386 and 486 systems use what is known as memory interleaving, which requires twice as many SIMMs and effectively doubles the bandwidth. The earliest SIMM sockets were conventional push-type sockets and these were soon replaced by ZIF sockets in which the SIMM was inserted at an angle, then tilted into an upright position. To remove one, the two metal or plastic clips at each end must be pulled to the side, then the SIMM must be tilted back, the earlier sockets used plastic retainer clips which were found to break, so steel clips replaced them
39.
InfoWorld
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InfoWorld is an information technology media business. Founded in 1978, it began as a monthly magazine, in 2007, it transitioned to a Web-only publication. Its parent company is International Data Group, and its sister publications include Macworld, InfoWorld is based in San Francisco, with contributors and supporting staff based across the United States. Since its founding, InfoWorlds readership has largely consisted of IT, InfoWorld focuses on how-to, analysis, and editorial content from a mixture of experienced technology journalists and working technology practitioners. The site averages 4.6 million monthly views and 1.1 million monthly unique visitors. The magazine was founded by Jim Warren in 1978 as Intelligent Machines Journal and it sold to IDG in late 1979. Early the next year, the name was changed to InfoWorld, in 1986, the Robert X. Cringely column began, for many, that pseudonymous column was the face of InfoWorld and its close ties to Silicon Valley in particular. Ethernet inventor Bob Metcalfe was CEO and publisher from 1991 to 1996, as the magazine transitioned to be exclusively Web-based, a final print edition was dated April 2,2007. In its Web incarnation, InfoWorld has transitioned away from widely available news stories to a focus on how-to, expert testing, InfoWorld also offers its content for mobile devices
40.
Byte (magazine)
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Byte magazine was an American microcomputer magazine, influential in the late 1970s and throughout the 1980s because of its wide-ranging editorial coverage. Coverage was in-depth with much detail, rather than user-oriented. Print publication ceased in 1998 and online publication in 2013, Byte started in 1975, shortly after the first personal computers appeared as kits advertised in the back of electronics magazines. Byte was published monthly, with a yearly subscription price of $10. In 1975 Wayne Green was the editor and publisher of 73 and his ex-wife, on May 25th we made a deal with the publisher of a small computer hobby magazine to take over as editor of a new publication which would start in August. Carl Helmers published a series of six articles in 1974 that detailed the design and construction of his Experimenters Computer System, in January 1975 this became the monthly ECS magazine with 400 subscribers. The last issue was published on May 12,1975 and in June the subscribers were mailed a notice announcing Byte magazine, carl wrote to another hobbyist newsletter, Micro-8 Computer User Group Newsletter, and described his new job as editor of Byte magazine. I got a note in the mail about two weeks ago from Wayne Green, publisher of 73 Magazine essentially saying hello and why dont you come up, the net result of a follow up is the decision to create BYTE magazine using the facilities of Green Publishing Inc. I will end up with the focus for the magazine. Virginia Londner Green had returned to 73 in the December 1974 issue, the first five issues of Byte were published by Green Publishing and the name was changed to Byte Publications starting with the February 1976 issue. Carl Helmers was a co-owner of Byte Publications, the first four issues were produced in the offices of 73 and Wayne Green was listed as the publisher. One day in November 1975 Wayne came to work and found that the Byte magazine staff had moved out, the February 1976 issue of Byte has a short story about the move. After a start which reads like a light opera with an episode or two reminiscent of the Keystone Cops, Byte magazine finally has moved into separate offices of its own. Wayne Green was not happy about losing Byte magazine so he was going to start a new one called Kilobyte, Byte quickly trademarked KILOBYTE as a cartoon series in Byte magazine. The new magazine was called Kilobaud, there was competition and animosity between Byte Publications and 73 Inc. but both remained in the small town of Peterborough, New Hampshire. Byte was able to attract advertising and articles from many well-knowns, soon-to-be-well-knowns, articles in the first issue included Which Microprocessor For You. by Hal Chamberlin, Write Your Own Assembler by Dan Fylstra and Serial Interface by Don Lancaster. Advertisements from Godbout, MITS, Processor Technology, SCELBI, and Sphere appear, early articles in Byte were do-it-yourself electronic or software projects to improve small computers. A continuing feature was Ciarcias Circuit Cellar, a column in which electronic engineer Steve Ciarcia described small projects to modify or attach to a computer, Byte ran Microsofts first advertisement, as Micro-Soft, to sell a BASIC interpreter for 8080-based computers
41.
Amiga Sidecar
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The Commodore A1060 Sidecar is an expansion hardware device developed by Commodore and released in 1986 for the Amiga 1000 computer. The PC side of the Sidecar was built around an Intel 8088 processor, all I/O procedures from the PC side are performed by the Amiga. Software was included to allow data to be exchanged easily between the PC and the Amiga side of the system, the Sidecar was available with an internal hard disk which was accessible from both the MS-DOS and AmigaOS environments. This was the first hard drive produced by Commodore for the Amiga, video display and user input were performed through the Amigas monitor, keyboard, and mouse. This allows the user to control both computers simultaneously, the Amiga Sidecar was a complete IBM PC XT system, with the exception of I/O devices and operations which are handled by the Amiga. Processor, Intel 8088 clocked at 4.77 MHz RAM,256 kB Graphics Emulation, sound Emulation, Dependent on Amiga settings. One internal 5.25 drive bay normally fitted with a 360K5 and these are the areas where the de facto business standard IBM PC excelled. Commodores intent was to let the Amiga take advantage of PC compatibility to shore up its weakness in this category of software. Bruce F. Webster wrote in the October 1985 BYTE after seeing the Amiga for the first time, the disk-controller hardware can already handle 5¼-inch drives. The keyboard is sufficiently populated support most MS-DOS programs, and the resolutions are, by an amazing coincidence. How hard would it be to build a box with the necessary CPU, not very hard, I would think—certainly not as hard as it has been for the folks at Dayna Communications to get MacCharlie, which attempts to get the Mac run MS-DOS software, up and running. The Sidecar was developed by Commodore Germany, as was all of the Commodore PC-architecture based development and it was relatively expensive and it required a non-trivial amount of desktop space compared to the Amiga 1000 by itself. The device was also taller than the Amiga 1000, which made it even more aesthetically disconnected from the main system. Besides the high price and the issues, other factors contributed to a lack of adoption of the Sidecar. The popular Amiga 500 could not be used with the Sidecar at all, due to the slot on the A500 residing on the left side of the chassis. Also, decent business and productivity software began to be released for AmigaOS and this concept was continued in the later Amiga 2000 unit, containing four ISA slots intended for PC emulation expandability. The big book of Amiga Hardware
42.
International Standard Book Number
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The International Standard Book Number is a unique numeric commercial book identifier. An ISBN is assigned to each edition and variation of a book, for example, an e-book, a paperback and a hardcover edition of the same book would each have a different ISBN. The ISBN is 13 digits long if assigned on or after 1 January 2007, the method of assigning an ISBN is nation-based and varies from country to country, often depending on how large the publishing industry is within a country. The initial ISBN configuration of recognition was generated in 1967 based upon the 9-digit Standard Book Numbering created in 1966, the 10-digit ISBN format was developed by the International Organization for Standardization and was published in 1970 as international standard ISO2108. Occasionally, a book may appear without a printed ISBN if it is printed privately or the author does not follow the usual ISBN procedure, however, this can be rectified later. Another identifier, the International Standard Serial Number, identifies periodical publications such as magazines, the ISBN configuration of recognition was generated in 1967 in the United Kingdom by David Whitaker and in 1968 in the US by Emery Koltay. The 10-digit ISBN format was developed by the International Organization for Standardization and was published in 1970 as international standard ISO2108, the United Kingdom continued to use the 9-digit SBN code until 1974. The ISO on-line facility only refers back to 1978, an SBN may be converted to an ISBN by prefixing the digit 0. For example, the edition of Mr. J. G. Reeder Returns, published by Hodder in 1965, has SBN340013818 -340 indicating the publisher,01381 their serial number. This can be converted to ISBN 0-340-01381-8, the check digit does not need to be re-calculated, since 1 January 2007, ISBNs have contained 13 digits, a format that is compatible with Bookland European Article Number EAN-13s. An ISBN is assigned to each edition and variation of a book, for example, an ebook, a paperback, and a hardcover edition of the same book would each have a different ISBN. The ISBN is 13 digits long if assigned on or after 1 January 2007, a 13-digit ISBN can be separated into its parts, and when this is done it is customary to separate the parts with hyphens or spaces. Separating the parts of a 10-digit ISBN is also done with either hyphens or spaces, figuring out how to correctly separate a given ISBN number is complicated, because most of the parts do not use a fixed number of digits. ISBN issuance is country-specific, in that ISBNs are issued by the ISBN registration agency that is responsible for country or territory regardless of the publication language. Some ISBN registration agencies are based in national libraries or within ministries of culture, in other cases, the ISBN registration service is provided by organisations such as bibliographic data providers that are not government funded. In Canada, ISBNs are issued at no cost with the purpose of encouraging Canadian culture. In the United Kingdom, United States, and some countries, where the service is provided by non-government-funded organisations. Australia, ISBNs are issued by the library services agency Thorpe-Bowker
