1.
Free On-line Dictionary of Computing
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The Free On-line Dictionary of Computing is an online, searchable, encyclopedic dictionary of computing subjects. It was founded in 1985 by Denis Howe and was hosted by Imperial College London, in May 2015, the site was updated to state that it was no longer supported by Imperial College Department of Computing. Howe has served as the editor-in-chief since the inception, with visitors to the website able to make suggestions for additions or corrections to articles. The dictionary incorporates the text of other resources, such as the Jargon File. Due to its availability under the GNU Free Documentation License, a license, it has in turn been incorporated in whole or part into other free content projects
2.
GNU Free Documentation License
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The GNU Free Documentation License is a copyleft license for free documentation, designed by the Free Software Foundation for the GNU Project. It is similar to the GNU General Public License, giving readers the rights to copy, redistribute, copies may also be sold commercially, but, if produced in larger quantities, the original document or source code must be made available to the works recipient. The GFDL was designed for manuals, textbooks, other reference and instructional materials, however, it can be used for any text-based work, regardless of subject matter. For example, the online encyclopedia Wikipedia uses the GFDL for all of its text. The GFDL was released in form for feedback in September 1999. After revisions, version 1.1 was issued in March 2000, version 1.2 in November 2002, the current state of the license is version 1.3. The first discussion draft of the GNU Free Documentation License version 2 was released on September 26,2006, material licensed under the current version of the license can be used for any purpose, as long as the use meets certain conditions. All previous authors of the work must be attributed, all changes to the work must be logged. All derivative works must be licensed under the same license, the full text of the license, unmodified invariant sections as defined by the author if any, and any other added warranty disclaimers and copyright notices from previous versions must be maintained. Technical measures such as DRM may not be used to control or obstruct distribution or editing of the document, the license explicitly separates any kind of Document from Secondary Sections, which may not be integrated with the Document, but exist as front-matter materials or appendices. Secondary sections can contain information regarding the authors or publishers relationship to the subject matter, if the material is modified, its title has to be changed. The license also has provisions for the handling of front-cover and back-cover texts of books, as well as for History, Acknowledgements, Dedications and Endorsements sections. These features were added in part to make the more financially attractive to commercial publishers of software documentation. Endorsements sections are intended to be used in official standard documents, the GFDL requires the ability to copy and distribute the Document in any medium, either commercially or noncommercially and therefore is incompatible with material that excludes commercial re-use. Material that restricts commercial re-use is incompatible with the license and cannot be incorporated into the work, one example of such liberal and commercial fair use is parody. Although the two work on similar copyleft principles, the GFDL is not compatible with the Creative Commons Attribution-ShareAlike license. These exemptions allow a GFDL-based collaborative project with multiple authors to transition to the CC BY-SA3, if it was not originally published on an MMC, it can only be relicensed if it were added to an MMC before November 1,2008. To prevent the clause from being used as a general compatibility measure, at the release of version 1.3, the FSF stated that all content added before November 1,2008 to Wikipedia as an example satisfied the conditions
3.
Microprocessor
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A microprocessor is a computer processor which incorporates the functions of a computers central processing unit on a single integrated circuit, or at most a few integrated circuits. Microprocessors contain both combinational logic and sequential digital logic, Microprocessors operate on numbers and symbols represented in the binary numeral system. The integration of a whole CPU onto a chip or on a few chips greatly reduced the cost of processing power. Integrated circuit processors are produced in numbers by highly automated processes resulting in a low per unit cost. Single-chip processors increase reliability as there are many electrical connections to fail. As microprocessor designs get better, the cost of manufacturing a chip generally stays the same, before microprocessors, small computers had been built using racks of circuit boards with many medium- and small-scale integrated circuits. Microprocessors combined this into one or a few large-scale ICs, the internal arrangement of a microprocessor varies depending on the age of the design and the intended purposes of the microprocessor. Advancing technology makes more complex and powerful chips feasible to manufacture, a minimal hypothetical microprocessor might only include an arithmetic logic unit and a control logic section. The ALU performs operations such as addition, subtraction, and operations such as AND or OR, each operation of the ALU sets one or more flags in a status register, which indicate the results of the last operation. The control logic retrieves instruction codes from memory and initiates the sequence of operations required for the ALU to carry out the instruction, a single operation code might affect many individual data paths, registers, and other elements of the processor. As integrated circuit technology advanced, it was feasible to manufacture more and more complex processors on a single chip, the size of data objects became larger, allowing more transistors on a chip allowed word sizes to increase from 4- and 8-bit words up to todays 64-bit words. Additional features were added to the architecture, more on-chip registers sped up programs. Floating-point arithmetic, for example, was not available on 8-bit microprocessors. Integration of the point unit first as a separate integrated circuit and then as part of the same microprocessor chip. Occasionally, physical limitations of integrated circuits made such practices as a bit slice approach necessary, instead of processing all of a long word on one integrated circuit, multiple circuits in parallel processed subsets of each data word. With the ability to put large numbers of transistors on one chip and this CPU cache has the advantage of faster access than off-chip memory, and increases the processing speed of the system for many applications. Processor clock frequency has increased more rapidly than external memory speed, except in the recent past, a microprocessor is a general purpose system. Several specialized processing devices have followed from the technology, A digital signal processor is specialized for signal processing, graphics processing units are processors designed primarily for realtime rendering of 3D images
4.
Motorola
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Motorola was an American multinational telecommunications company founded on September 25,1928, based in Schaumburg, Illinois. After having lost $4.3 billion from 2007 to 2009, Motorola Solutions is generally considered to be the direct successor to Motorola, as the reorganization was structured with Motorola Mobility being spun off. Motorola Mobility was acquired by Lenovo in 2014, Motorola designed and sold wireless network equipment such as cellular transmission base stations and signal amplifiers. Its business and government customers consisted mainly of wireless voice and broadband systems and these businesses are now part of Motorola Solutions. Google sold Motorola Home to the Arris Group in December 2012 for US$2.35 billion, Motorolas wireless telephone handset division was a pioneer in cellular telephones. Also known as the Personal Communication Sector prior to 2004, it pioneered the mobile phone with DynaTAC and it had staged a resurgence by the mid-2000s with the RAZR, but lost market share in the second half of that decade. Later it focused on smartphones using Googles open-source Android mobile operating system, the first phone to use the newest version of Googles open source OS, Android 2.0, was released on November 2,2009 as the Motorola Droid. The handset division was spun off into the independent Motorola Mobility. On May 22,2012, Google CEO Larry Page announced that Google had closed on its deal to acquire Motorola Mobility. On January 29,2014, Page announced that pending closure of the deal, on October 30,2014, Lenovo finalized its purchase of Motorola Mobility from Google. Galvin Manufacturing Corporation set up shop in a section of a rented building. The company had $565 in working capital and five employees, the first weeks payroll was $63. The companys first products were battery-eliminators, devices that enabled battery-powered radios to operate on household electricity, due to advances in radio technology, battery-eliminators soon became obsolete. Paul Galvin learned that some radio technicians were installing sets in cars and his team was successful, and Galvin was able to demonstrate a working model of the radio at the June 1930 Radio Manufacturers Association convention in Atlantic City, New Jersey. He brought home enough orders to keep the company in business. g, the company sold its first Motorola branded radio on June 23,1930, to H. C. Wall of Fort Wayne, Indiana, for $30, the Motorola brand name became so well-known that Galvin Manufacturing Corporation later changed its name to Motorola, Inc. Galvin Manufacturing Corporation began selling Motorola car-radio receivers to police departments, the companys first public safety customers included the Village of River Forest, Village of Bellwood Police Department, City of Evanston Police, Illinois State Highway Police, and Cook County Police. In the same year, the company built its research and development program with Dan Noble, a pioneer in FM radio and semiconductor technologies, the company produced the hand-held AM SCR-536 radio during World War II, which was vital to Allied communication
5.
Motorola 68030
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The Motorola 68030 is a 32-bit microprocessor in Motorolas 68000 family. The 68030 was the successor to the Motorola 68020, and was followed by the Motorola 68040, in keeping with general Motorola naming, this CPU is often referred to as the 030. The 68030 features 273,000 transistors with on-chip instruction and data caches of 256 bytes each and it also has an on-chip MMU but does not have a built in floating-point unit. The 68881 and the faster 68882 floating point unit chips could be used with the 68030, a lower cost version of the 68030, the Motorola 68EC030, was also released, lacking the on-chip MMU. It was commonly available in both 132 pin QFP and 128 pin PGA packages, the poorer thermal characteristics of the QFP package limited the full 68030 QFP variant to 33 MHz. The PGA 68030s included 40 MHz and 50 MHz versions, there was also a small supply of QFP packaged EC variants. Motorola used the process shrink to pack more hardware on the die, in case it was the MMU. The integration of the MMU made it more cost-effective than the 68020 with an external MMU, however, the 68030 can switch between synchronous and asynchronous buses without a reset. The 68030 also lacks some of the 68020s instructions but it lowers power draw by ~25%, when used with a 68020 bus, the 68030 did not differentiate itself in performance from the 68020 that it was derived from. However, the 68030 provides a synchronous bus interface which, if used. The finer manufacturing process allowed Motorola to scale the full-version processor to 50 MHz, the EC variety topped out at 40 MHz. It was also used in Unix workstations such as the Sun Microsystems Sun 3/80 desktop workstation, Laser printers, more recently, the 68030 core has also been adapted by Freescale into a microcontroller for embedded applications. The 68EC030 is a low cost version of the 68030, the difference between the two being that the 68EC030 does not have a memory management unit. The 68EC030 was used as the CPU of the Amiga 3000, one model of the Amiga 4000, and in the Cisco Systems 2500 Series router, a small-to-medium enterprise computer internetworking appliance. The 50 MHz speed is exclusive to the ceramic PGA package and this article is based on material taken from the Free On-line Dictionary of Computing prior to 1 November 2008 and incorporated under the relicensing terms of the GFDL, version 1.3 or later. 68030 images and descriptions at cpu-collection. de Official information about the Freescale MC68030 microcontroller
6.
Motorola 68060
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The Motorola 68060 is a 32-bit microprocessor from Motorola released in 1994. It is the successor to the Motorola 68040 and is the highest performing member of the 68000 series, two derivatives were produced, the 68LC060 and the 68EC060. There is an LC version, without an FPU and EC, without MMU, the 68060 design was led by Joe Circello. The 68060 shares most architectural features with the P5 Pentium, both have a very similar superscalar in-order dual instruction pipeline configuration, and an instruction decoder which breaks down complex instructions into simpler ones before execution. However, a significant difference is that the 68060 FPU is not pipelined and is therefore up to three times slower than the Pentium in floating point applications, in contrast to that, integer multiplications and bit shifting instructions are significantly faster on the 68060. An interesting feature of the 68060 is the ability to execute instructions in the address generation unit. Another point of interest is that large amounts of commercial compiled code were analyzed for clues as to which instructions would be the best candidates for performance optimization. Against the Pentium, the 68060 could perform better on mixed code, Pentiums decoder could not issue an FP instruction every opportunity, if the 68060s non-pipelined FPU could accept an instruction, it could be issued one by the decoder. This meant that optimizing for the 68060 was easier, no rules prevented FP instructions from being issued whenever was convenient for the other than well understood instruction latencies. However, with properly optimized and scheduled code, the Pentiums FPU was capable of double the clock for clock throughput of the 68060s FPU, the 68060 was the last development of the 680x0 series for general purpose use, abandoned in favor of the PowerPC chips. And the Unix world had moved onto various RISC platforms by the time the 060 was available, the 68060 was introduced at 50 MHz on Motorolas 0.6 µm manufacturing process. A few years later it was shrunk to 0.42 µm, developments of the basic core continue, intended for embedded systems. Here they are combined with a number of interfaces to reduce the overall complexity. A number of chips, each with different sets of interfaces, are sold under the names ColdFire, model numbers with even second-to-last digit were reserved for major revisions to the 680x0 core architecture. Model numbers with odd second-to-last digit were reserved for upgrades to the architecture of the previous chip, no 68050 or 68070 was ever produced by Motorola. There were, however, no major overhauls of the core architecture, similarly, the Motorola 68030 was a process improvement on the 68020 with the MMU and a small data cache moved on-chip. The 68030 was available in speed ratings up to 50 MHz, the jump from the 68000/68010 to the 68020/68030, however, represented a major overhaul, with too many individual changes to list here. By the time the 68060 was in production, Motorola had abandoned development of the 680x0-type chips in favor of the PowerPC, the 68060 was the last 680x0-type processor from Motorola
7.
Macintosh
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The Macintosh (/ˈmækᵻntɒʃ/ MAK-in-tosh, is a series of personal computers designed, developed, and marketed by Apple Inc. Steve Jobs introduced the original Macintosh computer on January 24,1984 and this was the companys first mass-market personal computer featuring an integral graphical user interface and mouse. This first model was renamed to Macintosh 128k for uniqueness amongst a populous family of subsequently updated models which are also based on Apples same proprietary architecture. Since 1998, Apple has largely phased out the Macintosh name in favor of Mac, Macintosh systems still found success in education and desktop publishing and kept Apple as the second-largest PC manufacturer for the next decade. In the 1990s, improvements in the rival Wintel platform, notably with the introduction of Windows 3.0, then Windows 95, gradually took market share from the more expensive Macintosh systems. The performance advantage of 68000-based Macintosh systems was eroded by Intels Pentium, even after a transition to the superior PowerPC-based Power Macintosh line in 1994, the falling prices of commodity PC components and the release of Windows 95 saw the Macintosh user base decline. In 1998, after the return of Steve Jobs, Apple consolidated its multiple consumer-level desktop models into the all-in-one iMac G3, since their transition to Intel processors in 2006, the complete lineup is entirely based on said processors and associated systems. Its current lineup comprises three desktops, and three laptops and its Xserve server was discontinued in 2011 in favor of the Mac Mini and Mac Pro. Apple also develops the operating system for the Mac, currently macOS version 10.12 Sierra, Macs are currently capable of running non-Apple operating systems such as Linux, OpenBSD, and Microsoft Windows with the aid of Boot Camp or third-party software. Apple does not license macOS for use on computers, though it did license previous versions of the classic Mac OS through their Macintosh clone program from 1995 to 1997. The Macintosh project was begun in 1979 by Jef Raskin, an Apple employee who envisioned an easy-to-use, in 1978 Apple began to organize the Apple Lisa project, aiming to build a next-generation machine similar to an advanced Apple III or the yet-to-be-introduced IBM PC. In 1979, Steve Jobs learned of the work on graphical user interfaces taking place at Xerox PARC. He arranged a deal in which Xerox received Apple stock options in return for which Apple would license their designs, the basic layout of the Lisa was largely complete by 1982, at which point Jobs continual suggestions for improvements led to him being kicked off the project. At the same time that the Lisa was becoming a GUI machine in 1979, the design at that time was for a low-cost, easy-to-use machine for the average consumer. Raskin was authorized to start hiring for the project in September 1979 and his initial team would eventually consist of himself, Howard, Joanna Hoffman, Burrell Smith, and Bud Tribble. Smiths design used fewer RAM chips than the Lisa, which production of the board significantly more cost-efficient. Though there were no memory slots, its RAM was expandable to 512 kB by means of soldering sixteen IC sockets to accept 256 kb RAM chips in place of the factory-installed chips. The final products screen was a 9-inch, 512x342 pixel monochrome display, burrels innovative design, combining the low production cost of an Apple II with the computing power of Lisas Motorola 68000 CPU, began to receive Jobs attentions
8.
Macintosh Quadra
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The Macintosh Quadra series is Apple Computers product family of professional high-end Apple Macintosh personal computers built using the Motorola 68040 central processing unit. The first two models in the Quadra line were introduced in 1991, and the name was used until the Power Mac was introduced in 1994, the product manager for the Quadra family was Frank Casanova who was also the Product Manager for the Macintosh IIfx. The first models were the Quadra 700 and Quadra 900, both introduced in 1991, the Quadra replaced the Macintosh II series as the high end computer in the Macintosh product line. The first computers to be part of the Macintosh Quadra series were the Quadra 700 and Quadra 900, the 900 was replaced in 1992 with the Quadra 950, with a CPU speed of 33 MHz. The line was joined by a number of 800-series machines in a new case design, starting with the Quadra 800. In 1993 the Quadra AV series was released, consisting of the 800-series Quadra 840AV, both included an AT&T Digital signal processor and S-Video and composite video input and output ports for video, as well as CD-quality microphone and audio output ports. The AV models also introduced PlainTalk, consisting of the text-to-speech software MacinTalk Pro, Apple hired marketing firm Lexicon Branding to come up with the name. Lexicon chose the name Quadra hoping to appeal to engineers by evoking technical terms like quadrant, the Quadra name was also used for the successors to the Centris models that briefly existed during 1993, The 610, the 650 and the 660AV. Centris was a series of systems between the Quadra on the high end and the LC on the low end, but it was later decided that there were too many product lines. Some machines of this era including the Quadra 605 were also sold as Performas, further adding to the confusion and dilution of what had been Apples prestige brand. The last use of the name was for the Quadra 630, which was a variation of the LC630 using a full Motorola 68040 instead of the LCs 68LC040, and introduced together with it in 1994. The 630 was the first Mac to use an IDE based drive bus for the hard disk drive. The first three Apple Workgroup Server models, the WGS60, the WGS80 and the WGS95 were based on the Centris 610, the Quadra 800, the transition to the Motorola 68040 was not as smooth as the previous transitions to the Motorola 68020 or Motorola 68030. Due to the Motorola 68040s split instruction and data caches, the Quadra had compatibility problems with self-modifying code, Apple partially fixed this by having the basic Mac OS memory copy call flush the caches. This solved the vast majority of stability problems, but negated much of the Motorola 68040s performance improvements, Apple also introduced a variant of the memory copy call that did not flush the cache. The new trap was defined in such a way that calling it on a version of Mac OS would simply call the previous memory copy routine
9.
Macintosh Centris
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Macintosh Centris is a line of Macintosh computers, introduced in 1993, that were built around the Motorola 68LC040 and 68040 CPUs. The name echoes other neoclassical prestige branding trends introduced at the time such as Lexus, the name was used for the Centris 610 and Centris 650, which were introduced in March 1993. It was also used a few months later for the Centris 660AV, the Centris 610 uses a 20 MHz 68LC040 CPU, which has no math coprocessor functions. It used a new pizza box case that was intended to be placed under the users computer monitor, Apples motherboard upgrades of this type were considered expensive, however, and were not a popular option. The Centris 610 also provided the base for the Workgroup Server 60, the base Centris 650 initially used a 25 MHz 68LC040 CPU, later models and all models with Ethernet built-in use a 68040. It uses the case as the older Macintosh IIvx and Macintosh IIvi computers. The newer Macintosh Quadra 650 and the Power Macintosh 7100 line of computers use the same case. The Centris 660AV uses a 25 MHz 68040 and also includes a signal processor chip from AT&T Corporation. Like other AV computers from Apple, it supports both video input and output, the name Centris was soon considered to be confusing to customers, and was abandoned. These Macs also existed during Apples transition from auto-eject floppy drives to manual-eject drives and this is why there are two different styles of floppy drive opening on these models. Some later Centris 660AV Macs have manual-eject floppy drives, so change was not exactly concurrent with the name change. Apples New AV Macs Tune In, Speak Out
10.
Macintosh Performa
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The initial series of models consisted of the Performa 200, based on the Macintosh Classic II, the Performa 400, based on the Macintosh LC II, and the Performa 600, based on the Macintosh IIvx. Before the existence of the Apple Store, Apple sold computers through authorized resellers, either brick, a typical reseller sold Macintosh computers to professionals, who purchased high-level applications and required performance and expansion capabilities. Consumers, however, purchased computers based on the best value, Apple wanted to sell their computers through department store chains, but this would conflict with existing authorized reseller agreements, in which a geographic area had only one reseller. To prevent these conflicts, Apple split the Macintosh line into professional, the professional line included the Classic, LC, Centris, Quadra, and Power Macintosh lines, and continued to be sold as-is. The consumer line included computers similar to the professional line labeled Performa, the Performa line was marketed differently from the professional line. To satisfy consumer-level budgets, the computers were sold bundled with home, most models were also bundled with a keyboard, mouse, an external modem and either a dot-29 or dot-39 pitch shadow mask CRT monitor. Although the Performa models resembled their professional counterpart on the software and hardware level. The Performa 600, for example, lacked the level-2 cache of the Macintosh IIvx it was based on, the Performa versions of the System software also introduced some features that were later included in mainstream system releases, most notably the Launcher. System 7.5 ended the separate Performa releases, the Performa marketing strategy failed for a number of reasons. Another factor was that working at mass-market retail stores lacked the specialized training Apple offered to its dealers. The Performa display models were often taken care of, the demo computers crashed. Consumers who may have been purchasing their first computer were steered away from the Performas because they werent compatible, Apple tried to address the training issue by hiring their own sales people to aid the store sales staff, most of them recruited from Macintosh user groups. Despite this, however, many returned Performa computers could not be serviced properly because the stores were not authorized Apple service centers, however, most experts attributed the failure to retailers favoring the Microsoft Windows line, especially after the introduction of Windows 95. Computers running Windows were generally cheaper, and encouraged by manufacturer spiffs, advertising co-ops, in addition, many stores preferred to sell their own branded white box PCs. The significant number of nearly identical models across its multiple hardware lines caused Apple to rethink its marketing strategy, critics of the Performa line, including some Mac users, argued the Performas were generally underpowered relative to higher-end Mac models. Some critics cited the large and confusing array of different Performa models, reference, * X Denotes multiple variant of the same model. List of Performa and equivalent models Mac Performa flat top 475 Mactracker - information on every Mac, Mac clone, and Apple products
11.
Motorola 68040
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This article is based on material taken from the Free On-line Dictionary of Computing prior to 1 November 2008 and incorporated under the relicensing terms of the GFDL, version 1.3 or later. The Motorola 68040 is a 32-bit microprocessor from Motorola, released in 1990 and it is the successor to the 68030 and is followed by the 68060. In keeping with general Motorola naming, the 68040 is often referred to as simply the 040, in Apple Macintosh computers, the 68040 was found mainly in the Macintosh Quadra, which was named for the chip. The fastest 68040 processor was clocked at 40 MHz and it was used in the Quadra 840AV. The more expensive models in the Macintosh Centris line also used the 68040, while the cheaper Quadra, Centris, the 68040 was the first 680x0 family member with an on-chip Floating-Point Unit. It thus included all of the functionality that previously required external chips, namely the FPU and Memory Management Unit and it also had split instruction and data caches of 4 kilobytes each. It was fully pipelined, with six stages, unfortunately, the 68040 ran into the transistor budget limit early in design. While the MMU did not take many transistors—indeed, having it on the same die as the CPU actually saved on transistors—the FPU certainly did. Motorolas 68882 external FPU was known as a high performance unit. The Motorola floating point support package emulated these instructions in software under interrupt, as this was an exception handler, heavy use of the transcendental functions caused severe performance penalties. Heat was always a problem throughout the 68040s life, while it delivered over four times the per-clock performance of the 68020 and 68030, the chips complexity and power requirements came from a large die and large caches. This affected the scaling of the processor and it was never able to run with a rate exceeding 40 MHz. A50 MHz variant was planned, but canceled, overclocking enthusiasts reported success reaching 50 MHz using a 100 MHz oscillator instead of an 80 MHz part and the then novel technique of adding oversized heat sinks with fans. The 68040 offered the same features as the Intel 80486, but on a clock-for-clock basis could significantly outperform the Intel chip in integer, however, the 80486 had the ability to be clocked significantly faster without suffering from overheating problems. In late 1991, as the higher-end Macintosh desktop lineup transitioned to the 040, versions of the 68040 were created for specific market segments, including the 68LC040, which removed the FPU, and the 68EC040, which removed both the FPU and MMU. The 16 MHz and 20 MHz parts were never qualified and used as prototyping samples,25 MHz and 33 MHz grades featured across the whole line, but until around 2000 the 40 MHz grade was only for the full 68040. A planned 50 MHz grade was canceled after it exceeded the design envelope. For more information on the instructions and architecture, see Motorola 68000, the 68EC040 is a version of the Motorola 68040 microprocessor, intended for embedded controllers
12.
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
13.
Amiga 4000
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The Commodore Amiga 4000, or A4000, is the successor of the A2000 and A3000 computers. There are two models, the A4000/040 released in October 1992 with a Motorola 68040 CPU, and the A4000/030 released in April 1993 with a Motorola 68EC030, the Amiga 4000 introduces the Advanced Graphics Architecture chipset with enhanced graphics and continues the A3000s system architecture. However, the SCSI from previous Amigas was replaced by the lower-cost Parallel ATA, the original A4000 is housed in a beige horizontal desktop box with a separate keyboard. Later, Commodore released an expanded version called the A4000T. The stock A4000 shipped with either a Motorola 68EC030 or 68040 CPU,2 MB of Amiga Chip RAM, there is a non-functional jumper that was intended to expand the chip RAM to 8MB. Later, third-party developers created various CPU expansion boards featuring higher rated 68040,68060, such hardware also typically offers faster and higher capacity RAM. Unlike previous Amiga models, early A4000 machines have the CPU mounted in an expansion board, later revisions of the A4000 have the CPU and 2 MB RAM surface-mounted on the motherboard in an effort to reduce costs. These machines are known as the A4000-CR and the surface-mounted CPU is a 68EC030, the cost-reduced models also make use of a non-rechargeable lithium battery for real-time clock battery backup rather than a rechargeable NiCd battery. The NiCd backup battery is one of the most common causes of problems in a device that uses one because it has a tendency to eventually leak. The released fluids are somewhat corrosive and can damage the circuitry. The A4000 is the first Amiga model to have shipped with Commodores third-generation Amiga chipset, as the name implies, AGA introduces improved graphical abilities, specifically, a palette expanded from 12-bit color depth to 24-bit and new 128,256 and 262,144 color modes. Unlike earlier Amiga chipsets, all modes are available at all display resolutions. AGA also improves sprite capacity and graphics performance, the on-board sound hardware remains identical to that of the original Amiga chipset, namely, four DMA-driven 8-bit PCM channels, with two channels for the left speaker and two for the right. The A4000 has a number of Amiga-specific connectors including two DE-9 ports for joysticks, mice, and light pens, a standard 25-pin RS-232 serial port and a 25-pin Centronics parallel port. As a result, at launch the A4000 was compatible with many existing Amiga peripherals, such as, MIDI devices, serial modems, like the just-earlier Amiga model, the 3000, the A4000 has four internal 32-bit Zorro III expansion slots. This expansion bus allows the use of devices which comply with the AutoConfig standard, such as cards, audio cards, network cards, SCSI controllers. The three ISA slots can be activated by use of a bridgeboard, which connects the Zorro, such bridgeboards typically feature on-board IBM-PC-compatible hardware, including Intel 80286,80386, or 80486 microprocessors allowing emulation of an entire IBM-PC system in hardware. Compatible ISA cards may then be installed into the two remaining ISA slots, the A4000 shipped with AmigaOS3.0, consisting of Workbench 3.0 and Kickstart 3.0, which together provide a single-user multi-tasking operating system and support for the built-in hardware
14.
Amiga 4000T
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The Amiga 4000T, also known as A4000T, is a tower version of Commodores A4000 personal computer. Despite the subsequent demise of Escom, production was continued by QuikPak in North America into at least 1997, the A4000T was the only Amiga ever to have both SCSI and IDE interfaces built-in on the motherboard. library to be stored on disk. Modularity was another aspect to the machine, with the CPU, audio, video. The machine was targeted as a high-end video workstation with expandability in mind and its motherboard contains two Amiga Video Slots, five 100-pin Zorro III slots, and 4 ISA slots, and its case can accommodate up to six drives. Up to 16 MB of RAM can be installed on the motherboard, while additional RAM can be installed on some CPU boards and this was the last computer to be released by Commodore International. Only a couple hundred 4000Ts were produced before the company folded
15.
Workstation
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A workstation is a special computer designed for technical or scientific applications. Intended primarily to be used by one person at a time, they are connected to a local area network. Workstations offered higher performance than mainstream personal computers, especially with respect to CPU and graphics, memory capacity, and multitasking capability. Typically, the factor is that of a desktop computer, consist of a high resolution display, a keyboard and a mouse at a minimum. Workstations were the first segment of the market to present advanced accessories. The increasing capabilities of mainstream PCs in the late 1990s have blurred the lines somewhat with technical/scientific workstations, perhaps the first computer that might qualify as a workstation was the IBM1620, a small scientific computer designed to be used interactively by a single person sitting at the console. One peculiar feature of the machine was that it lacked any actual arithmetic circuitry, to perform addition, it required a memory-resident table of decimal addition rules. This saved on the cost of logic circuitry, enabling IBM to make it inexpensive, the machine was code-named CADET and rented initially for $1000 a month. In 1965, IBM introduced the IBM1130 scientific computer, which was meant as the successor to the 1620, both of these systems came with the ability to run programs written in Fortran and other languages. Both the 1620 and the 1130 were built into roughly desk-sized cabinets, both were available with add-on disk drives, printers, and both paper-tape and punched-card I/O. A console typewriter for direct interaction was standard on each, early examples of workstations were generally dedicated minicomputers, a system designed to support a number of users would instead be reserved exclusively for one person. A notable example was the PDP-8 from Digital Equipment Corporation, regarded to be the first commercial minicomputer, Lisp Machines were commercialized beginning 1980 by companies like Symbolics, Lisp Machines, Texas Instruments and Xerox. The first computer designed for single-users, with high-resolution graphics facilities was the Xerox Alto developed at Xerox PARC in 1973, other early workstations include the Terak 8510/a, Three Rivers PERQ and the later Xerox Star. Meanwhile, DARPAs VLSI Project created several spinoff graphics products as well, notably the SGI3130 and it was not uncommon to differentiate the target market for the products, with Sun and Apollo considered to be network workstations, while the SGI machines were graphics workstations. As RISC microprocessors became available in the mid-1980s, these were adopted by many workstation vendors, workstations tended to be very expensive, typically several times the cost of a standard PC and sometimes costing as much as a new car. However, minicomputers sometimes cost as much as a house, additionally, workstations, given their more specialized nature, tend to have higher profit margins than commodity-driven PCs. Additionally, the companies that make the products tend to have very good repair/replacement plans, some low-cost workstations are still expensive by PC standards, but offer binary compatibility with higher-end workstations and servers made by the same vendor. This allows software development to take place on low-cost desktop machines, Graphics workstations often shipped with graphics accelerators
16.
Alpha Microsystems
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Alpha Microsystems is a computer company founded in 1977 by John French, Dick Wilcox and Bob Hitchcock. The first Alpha Micro computer was the S-100 AM-100, based upon the WD16 microprocessor chipset from Western Digital, early peripherals included standard Computer terminals, Fortran punch card readers,100 baud rate acoustic coupler modems, and 10 MB CDC Hawk hard drives with removable disk packs. The companys primary claim to fame was selling inexpensive minicomputers that provided multi-user power using an operating system called AMOS. The operating system on the 68000 machines was called AMOS/L, the operating system had major similarities to the operating system of the DEC PDP-11. As Motorola stopped developing their 68000 product, Alpha Micro started to move to the x86 CPU family and this was initially done with the Falcon cards, allowing standard DOS and later Windows-based PCs to run AMOS applications on the 68000-series CPU on the Falcon card. The work done on AMPC became the foundation for AMOS8. x, which runs natively on x86, for application development, AMOS used a proprietary BASIC-like language called AlphaBASIC. Older versions interpreted a tokenized executable file, later versions translate the tokenized executable into x86 code for performance. Other programming languages included AlphaFortran, AlphaLisp and AlphaPascal, gradually, Alpha Micro has transitioned to charging for their software as hardware becomes more of a commodity item. This software would function similar to Citrix or the X Windowing system, the Alpha Micro computer has never achieved mainstream name recognition, though it has been traditionally popular in certain vertical markets, particularly medical, law, and dental offices. There were two organizations which produced periodic newsletters and held meetings, AMUS, and IAMDA. It was typically at annual meetings that the latest hardware and software products were announced by Alpha Microsystems. Alpha Microsystems website Alpha Microsystems Document Archive Marcus Bennetts AM Documentation Store An emulator for the WD16 based system is available, the Alpha Micro Phun Machine, running on an AMOS-based Eagle 300 system. Alpha Micro 1000 page on www. old-computers. com AMUS website
17.
HP 9000
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HP9000 is a line of workstation and server computer systems produced by the Hewlett-Packard Company. The native operating system for almost all HP9000 systems is HP-UX, the HP9000 brand was introduced in 1984 to encompass several existing technical workstation models previously launched in the early 1980s. The HP9000 line was discontinued in 2008, being superseded by the HP Integrity platform running HP-UX, the first HP9000 models comprised the HP9000 Series 200 and Series 500 ranges. These were followed by the HP9000 Series 300 and Series 400 workstations which also used 68k-series microprocessors. From the mid-1980s onwards, HP started to switch over to its own based on its proprietary PA-RISC ISA, for the Series 600,700,800. More recent models use either the PA-RISC or its successor, the HP/Intel IA-64 ISA, HP released the Series 400, also known as the Apollo 400, after acquiring Apollo Computer in 1989. These models had the ability to run either HP-UX or Apollos Domain/OS, from the early 1990s onwards, HP replaced the HP9000 Series numbers with an alphabetical Class nomenclature. In 2001, HP again changed the scheme for their HP9000 servers. The A-class systems were renamed as the rp2400s, the L-class became the rp5400s, the rp prefix signified a PA-RISC architecture, while rx was used for IA-64-based systems, later rebranded HP Integrity. On 30 April 2008, HP announced end of sales for the HP9000, the last order date for HP9000 systems was 31 December 2008 and the last ship date was 1 April 2009. The last order date for new HP9000 options was December 31,2009, HP intends to support these systems through to 2013, with possible extensions. The end of life for HP9000 also marks the end of an era, the first model was the HP 9826A, followed by the HP 9836A. Later, a version of the 9836 was introduced. There was also a rack-mount version, the HP 9920A and these were all based on the Motorola 68000 chip. There were S versions of the models that included memory bundled in, when HP-UX was included as an OS, there was a U version of the 9836s and 9920 that used the 68012 processor. The model numbers included the letter U, later versions of the Series 200s included the 9816,9817, and 9837. These systems were renamed as the HP Series 200 line, before being renamed again as part HP9000 family. There was also a version of the Series 200 called the Integral
18.
NeXT
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NeXT was founded by Jobs after he was ousted at Apple, along with several co-workers. NeXT introduced the first NeXT Computer in 1988, and the smaller NeXTstation in 1990, the NeXT computers experienced relatively limited sales, with estimates of about 50,000 units shipped in total. Nevertheless, their innovative object-oriented NeXTSTEP operating system and development environment were highly influential, NeXT later released much of the NeXTSTEP system as a programming environment standard called OpenStep. NeXT withdrew from the business in 1993 to concentrate on marketing OPENSTEP for Mach, its own OpenStep implementation. NeXT also developed WebObjects, one of the first enterprise Web application frameworks, Apple purchased NeXT in 1997 for $429 million, and 1.5 million shares of Apple stock. As part of the agreement, Steve Jobs, Chairman and CEO of NeXT Software, returned to Apple, the founder promised to merge software from NeXT with Apples hardware platforms, eventually resulting in macOS, iOS, watchOS and tvOS. Parts of these systems incorporated the OPENSTEP foundation. In 1985, Apple co-founder Steve Jobs led Apples SuperMicro division, the Macintosh had been successful on university campuses partly because of the Apple University Consortium, which allowed students and institutions to buy the computers at a discount. The consortium had earned more than $50 million on computers by February 1984, while chairman, Jobs visited university departments and faculty members to sell Macintosh. Jobs met Paul Berg, a Nobel Laureate in chemistry, at a luncheon held in Silicon Valley to honor François Mitterrand, wet labs were prohibitively expensive for lower-level courses and were too complex to be simulated on personal computers of the time. Jobs was intrigued by Bergs concept of a workstation and contemplated starting a higher education company in the fall of 1985. Jobs division did not release upgraded versions of the Macintosh and most of the Macintosh Office, as a result, sales plummeted, and Apple was forced to write off millions of dollars in unsold inventory. Apples chief executive officer John Sculley ousted Jobs from his role at Apple. Later that year, Jobs began a struggle to regain control of the company. The board of directors sided with Sculley while Jobs took a visit to Western Europe. After several months of being sidelined, Jobs resigned from Apple on September 13,1985 and he told the board he was leaving to set up a new computer company, and that he would be taking several Apple employees from the SuperMicro division with him. He also told the board that his new company would not compete with Apple, Jobs named his new company Next, Inc. A number of former Apple employees followed him to Next, including Joanna Hoffman, Bud Tribble, George Crow, Rich Page, Susan Barnes, Susan Kare, and Danl Lewin
19.
Motorola 68000 series
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The Motorola 68000 series is a family of 32-bit complex instruction set computer microprocessors. During the 1980s and early 1990s, they were popular in personal computers and they were most well known as the processors powering the early Apple Macintosh, the Commodore Amiga, the Sinclair QL, the Atari ST, the WeatherStar, the Sega Genesis, and several others. However, they became most well known as the processors powering desktop computers such as the Apple Macintosh, the Commodore Amiga, the Sinclair QL, the Atari ST, and several others. The 68000 was also the processor of choice in the 1980s for Unix workstations and servers from firms such as Sun Microsystems, NeXT and Silicon Graphics. There was a 68000 version of CP/M called CP/M-68K, which was proposed to be the Atari ST operating system. Also, and perhaps most significantly, the first several versions of Adobes PostScript interpreters were 68000-based, the 68000 in the Apple LaserWriter and LaserWriter Plus was clocked faster than the version used then in Macintosh computers. Thereafter, Adobe generally preferred a RISC for its processor, as its competitors, with their PostScript clones, had gone with RISCs. The early 68000-based Adobe PostScript interpreters and their hardware were named for cold war U. S. rockets and missiles, Atlas, Redstone, today, these systems are either end-of-line, or are using different processors. Since these platforms had their peak in the 1980s, their original manufacturers are unlikely to support an operating system for this hardware or are even out of business. However, the GNU/Linux, NetBSD and OpenBSD operating systems include support for 68000 processors. The 68000 processors were used in the Sega Genesis and SNK Neo Geo consoles as the main CPU. Many arcade boards also used 68000 processors including boards from Capcom, SNK, microcontrollers derived from the 68000 family have been used in a huge variety of applications. For example, CPU32 and ColdFire microcontrollers have been manufactured in the millions as automotive engine controllers, people who are familiar with the PDP-11 or VAX usually feel comfortable with the 68000. With the exception of the split of general purpose registers into specialized data and address registers and it had a more orthogonal instruction set than those of many processors that came before and after. That is, it was possible to combine operations freely with operands. This property made programming relatively easy for humans, and also made it easier to write code generators for compilers, there was no 68050, though at one point it was a project within Motorola. Many of these optimizations were included with the 68060 and were part of its design goals. There is also no revision of the 68060, as Motorola was in the process of shifting away from the 68000 and 88k processor lines into its new PowerPC business, had it been, it would have been a revised 68060, likely with a superior FPU
20.
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
21.
Memory management unit
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It is usually implemented as part of the central processing unit, but it also can be in the form of a separate integrated circuit. An MMU effectively performs virtual memory management, handling at the same memory protection, cache control, bus arbitration and, in simpler computer architectures. Modern MMUs typically divide the address space into pages, each having a size which is a power of 2, usually a few kilobytes. The bottom bits of the address are left unchanged, the upper address bits are the virtual page numbers. Most MMUs use a table of items called a page table, containing one page table entry per page. An associative cache of PTEs is called a translation lookaside buffer and is used to avoid the necessity of accessing the main memory every time a virtual address is mapped, other MMUs may have a private array of memory or registers that hold a set of page table entries. The physical page number is combined with the offset to give the complete physical address. A PTE may also include information about whether the page has been written to, when it was last used, what kind of processes may read and write it, and whether it should be cached. Sometimes, a PTE prohibits access to a page, perhaps because no physical random access memory has been allocated to that virtual page. In this case, the MMU signals a page fault to the CPU, the operating system then handles the situation, perhaps by trying to find a spare frame of RAM and set up a new PTE to map it to the requested virtual address. If no RAM is free, it may be necessary to choose an existing page, using some replacement algorithm, with some MMUs, there can also be a shortage of PTEs, in which case the OS will have to free one for the new mapping. Typically, an operating system assigns each program its own address space. An MMU also mitigates the problem of fragmentation of memory, after blocks of memory have been allocated and freed, the free memory may become fragmented so that the largest contiguous block of free memory may be much smaller than the total amount. With virtual memory, a range of virtual addresses can be mapped to several non-contiguous blocks of physical memory. Later microprocessors placed the MMU together with the CPU on the integrated circuit, as did the Intel 80286. While this article concentrates on modern MMUs, commonly based on pages and those are occasionally also present on modern architectures. The x86 architecture provided segmentation, rather than paging, in the 80286, most modern systems divide memory into pages that are 4-64 KB in size, often with the capability to use huge pages from 2 MB to 1 GB in size. Page translations are cached in a translation lookaside buffer, some systems, mainly older RISC designs, trap into the OS when a page translation is not found in the TLB
22.
Instruction pipelining
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Instruction pipelining is a technique that implements a form of parallelism called instruction-level parallelism within a single processor. It therefore allows faster CPU throughput than would otherwise be possible at a clock rate. The basic instruction cycle is broken up into a series called a pipeline, the first step is always to fetch the instruction from memory, the final step is usually writing the results of the instruction to processor registers or to memory. Just as the goal of the line is to keep each assembler productive at all times. Pipelining lets the computers cycle time be the time of the slowest step, Pipelining increases instruction throughput by performing multiple operations at the same time, but does not reduce latency, the time needed to complete a single instruction. Indeed, pipelining may increase due to additional overhead from breaking the computation into separate steps. The term pipeline is an analogy to the fact there is fluid in each link of a pipeline. Central processing units are driven by a clock, each clock pulse need not do the same thing, rather, logic in the CPU directs successive pulses to different places to perform a useful sequence. As another example, reading an instruction out of a memory unit cannot be done at the time that an instruction writes a result to the same memory unit. The number of dependent steps varies with the machine architecture, for example, The 1956-1961 IBM Stretch project proposed the terms Fetch, Decode, and Execute that have become common. Many designs include pipelines as long as 7,10 and even 20 stages, the later Prescott and Cedar Mill Netburst cores from Intel, used in the latest Pentium 4 models and their Pentium D and Xeon derivatives, have a long 31-stage pipeline. The Xelerated X10q Network Processor has a more than a thousand stages long. The remaining stages are used to coordinate accesses to memory and on-chip function units, as the pipeline is made deeper, a given step can be implemented with simpler circuitry, which may let the processor clock run faster. Such pipelines may be called superpipelines, a processor is said to be fully pipelined if it can fetch an instruction on every cycle. Thus, if some instructions or conditions require delays that inhibit fetching new instructions, the model of sequential execution assumes that each instruction completes before the next one begins, this assumption is not true on a pipelined processor. A situation where the result is problematic is known as a hazard. Instruction 2 would be fetched at t2 and would be complete at t6, the first instruction might deposit the incremented number into R5 as its fifth step at t5. But the second instruction might get the number from R5 in its second step at time t3 and it seems that the first instruction would not have incremented the value by then
23.
Motorola 68881
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The Motorola 68881 and Motorola 68882 were floating-point coprocessor devices that were used in some computer systems in conjunction with the 68020 or 68030 microprocessors. The addition of one of these devices added substantial cost to the computer, at the time, this feature was useful mostly for scientific and mathematical software. The 68020 and 68030 CPUs were designed with the separate 68881 chip in mind, the 68881 had eight 80-bit data registers. It allowed seven different modes of representation, including single-precision, double-precision. It was designed specifically for floating-point math and was not a general-purpose CPU, for example, when an instruction required any address calculations, the main CPU would handle them before the 68881 took control. The CPU/FPU pair were designed such that both could run at the same time, when the CPU encountered a 68881 instruction, it would hand the FPU all operands needed for that instruction, and then the FPU would release the CPU to go on and execute the next instruction. The 68882 was a version of the 68881, with better pipelining. Its instruction set was exactly the same as that of the 68881, the 68882 is pin compatible with the 68881 and can be used as a direct replacement in most systems. Some third-party Amiga and Atari products used the 68881 or 68882 as a peripheral to the 68000. When the Motorola 68040 processor was introduced, it included the FPU internally, no statistics are listed for the 16 MHz and 20 MHz 68882, though these chips were indeed produced. Notes freescale. com - Motorola MC68000 Family Programmers Reference Manual faqs. org - comp. sys. m68k FAQ
24.
Motorola 68020
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The Motorola 68020 is a 32-bit microprocessor from Motorola, released in 1984. It is the successor to the Motorola 68010 and is succeeded by the Motorola 68030, a lower cost version was also made available, known as the 68EC020. In keeping with naming practices common to Motorola designs, the 68020 is usually referred to as the 020, the 68020 had 32-bit internal and external data and address buses, compared to the early 680x0 models with 16-bit data and 24-bit address buses. The 68020s ALU was also natively 32-bit, so could perform 32-bit operations in one clock, newer packaging methods allowed the 020 to feature more external pins without the large size that the earlier dual in-line package method required. The 68EC020 lowered cost through a 24-bit address bus, the 68020 was produced at speeds ranging from 12 MHz to 33 MHz. The 68020 added many improvements over the 68010 including a 32-bit arithmetic logic unit, 32-bit external data and address buses, extra instructions, the 68020 had a proper three-stage pipeline. Though the 68010 had a mode, which sped loops through what was effectively a tiny instruction cache. The 68020 replaced this with an instruction cache of 256 bytes. The previous 68000 and 68010 processors could only access word and long word data in memory if it were word-aligned, the 68020 had no alignment restrictions on data access. Naturally, unaligned accesses were slower than aligned accesses because they required an extra memory access, the 68020 has a coprocessor interface supporting up to eight coprocessors. The main CPU recognizes F-line instructions, and uses special bus cycles to interact with a coprocessor to execute these instructions, two types of coprocessors were defined, the floating point unit and the paged memory management unit. Only one PMMU can be used with a CPU, in principle multiple FPUs could be used with a CPU, but it was not commonly done. The coprocessor interface is asynchronous, so it is possible to run the coprocessors at a different clock rate than the CPU, multiprocessing support was implemented externally by the use of a RMC pin to indicate an indivisible read-modify-write cycle in progress. All other processors had to hold off memory accesses until the cycle was complete, software support for multiprocessing included the TAS, CAS and CAS2 instructions. In a multiprocessor system, coprocessors could not be shared between CPUs, while the 68000 had supervisor mode, it did not meet the Popek and Goldberg virtualization requirements due to the single instruction MOVE from SR being unprivileged but sensitive. Under the 68010 and later, this was made privileged, to support virtualization software. The new addressing modes added scaled indexing and another level of indirection to many of the pre-existing modes, though it was not intended, these new modes made the 68020 very suitable for page printing, most laser printers in the early 1990s had a 68EC020 at their core. The 68020 had a small 256-byte direct-mapped instruction cache, arranged as 64 four-byte entries, although small, it still made a significant difference in the performance of many applications
25.
Overclocking
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Commonly operating voltage is also increased to maintain a components operational stability at accelerated speeds. However semiconductor devices operated at a higher frequencies and voltages generate additional heat, so most overclocking attempts increase power consumption, an overclocked device may be unreliable or fail completely if the additional heat load is not removed or power delivery components cannot meet increased power demands. Many device warranties state that overclocking and/or over-specification voids any warranty, the purpose of overclocking is to gain additional performance from a given component by increasing its operating speed. The trade-offs are an increase in consumption and fan noise for the targeted components. Most components are designed with a margin of safety to deal with operating conditions outside of a control, examples are ambient temperature. Past this speed the device starts giving incorrect results, which can cause malfunctions, at this point an increase in operating voltage of a part may allow more headroom for further increases in clock speed, but increased voltage can also significantly increase heat output. Overzealous use of voltage and/or inadequate cooling can rapidly degrade a devices performance to the point of failure, conversely, the primary goal of underclocking is to reduce power consumption and the resultant heat generation of a device, with the trade-offs being lower clock speeds and reductions in performance. Underclocking is almost always involved in the stages of Undervolting which seeks to find the highest clock speed that a processor will stably operate at a given voltage. A given device may operate correctly at its stock speed even when undervolted, a lower bound is where the device itself fails to function and/or the supporting circuity cannot reliably communicate with the part. Underclocking and undervolting are usually attempted if a system needs to operate silently, overclocking has become more accessible with motherboard makers offering overclocking as a marketing feature on their mainstream product lines. However, the practice is embraced more by enthusiasts than professional users, as overclocking carries a risk of reduced reliability, accuracy and damage to data and equipment. Additionally it is important to note that most manufacturer warranties and service agreements do not cover overclocked components nor any incidental damage caused by their use, overclocking offers several draws for overclocking enthusiasts. Overclocking allows testing of components at speeds not currently offered by the manufacturer, a general trend in the computing industry is that new technologies tend to debut in the high-end market first, then later trickle down to the performance and mainstream market. If the high-end part only differs by a clock speed. Others will purchase a lower-cost model of a component in a product line. Technically any component that uses a timer to synchronize its internal operations can be overclocked, most efforts for computer components however focus on specific components such as processors, video cards, motherboard chipsets, and RAM. Most modern processors derive their effective operating speeds by multiplying a base clock by an internal multiplier within the processor to attain their final speed. Some systems allow additional tuning of other clocks that influence the bus clock speed that, a practical consideration if a component can be overclocked is if the necessary adjustments to change clock speeds are actually accessible to the user
26.
Intel 80486
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The Intel 80486, also known as the i486 or 486, is a higher performance follow-up to the Intel 80386 microprocessor. It represents a generation of binary compatible CPUs since the original 8086 of 1978. A50 MHz 80486 executes around 40 million instructions per second on average and is able to reach 50 MIPS peak performance, the i486 does not have the usual 80-prefix because of a court ruling that prohibits trademarking numbers. Later, with the introduction of the Pentium brand, Intel began branding its chips with words rather than numbers, the 80486 was announced at Spring Comdex in April 1989. At the announcement, Intel stated that samples would be available in the quarter of 1989. The first 80486-based PCs were announced in late 1989, but some advised that people wait until 1990 to purchase a 80486 PC because there were reports of bugs. From a performance point of view, the architecture of the i486 is a vast improvement over the 80386 and it has an on-chip unified instruction and data cache, an on-chip floating-point unit and an enhanced bus interface unit. Due to the tight pipelining, sequences of simple instructions could sustain a single clock cycle throughput and these improvements yielded a rough doubling in integer ALU performance over the 386 at the same clock rate. A 16-MHz 80486 therefore had a similar to a 33-MHz 386. An 8 kB on-chip SRAM cache stores the most recently used instructions, the 386 had no such internal cache but supported a slower off-chip cache. Tightly coupled pipelining completes a simple instruction like ALU reg, reg or ALU reg, the 386 needed two clock cycles to do this. New instructions, XADD, BSWAP, CMPXCHG, INVD, WBINVD, virtual addresses were then normally mapped onto physical addresses by the paging system except when it was disabled. Just as with the 80386, circumventing memory segmentation could substantially improve performance in some operating systems, on a typical PC motherboard, either four matched 30-pin SIMMs or one 72-pin SIMM per bank were required to fit the 80486s 32-bit data bus. The address bus used 30-bits complemented by four byte-select pins to allow for any 8/16/32-bit selection and this meant that the limit of directly addressable physical memory was 4 gigabytes as well. There are several suffixes and variants, marked as upgrade processors, some models had different pinouts or voltage handling abilities from standard chips of the same speed stepping. Fitted to a coprocessor or OverDrive socket on the motherboard, worked the same as the i487SX, the specified maximum internal clock frequency ranged from 16 to 100 MHz. The 16 MHz i486SX model was used by Dell Computers, one of the few 80486 models specified for a 50 MHz bus initially had overheating problems and was moved to the 0.8 micrometre fabrication process. Certain steppings of the DX4 also officially supported 50 MHz bus operation but was a seldom used feature
27.
PowerBook
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The PowerBook was a line of Macintosh laptop computers that was designed, manufactured and sold by Apple Computer, Inc. from 1991 to 2006. During its lifetime, the PowerBook went through major revisions and redesigns. In 1999, the line was supplemented by the consumer iBook range, the PowerBook and iBook lines were discontinued and replaced by the MacBook Pro and MacBook families respectively by 2006. In September 1989, Apple Inc. released the Macintosh Portable, however, its price, size, and weight made actual portability difficult. Because of this, the demand for a true portable Macintosh was not met, in October 1991 Apple released the first three PowerBooks, the low-end PowerBook 100, the more powerful PowerBook 140, and the high end PowerBook 170, the only one with an active matrix display. In the early days of Microsoft Windows, many notebooks came with a clip on trackball that fit on the edge of the keyboard molding, as usage of DOS gave way to the graphical user interface, the PowerBooks arrangement became the standard layout all future notebook computers would follow. The PowerBook 140 and 170 were the original PowerBook designs, while the PowerBook 100 was the result of Apple having sent the schematics of the Mac Portable to Sony, the PowerBook 100, however, did not sell well until Apple dropped the price substantially. The 100 series PowerBooks were intended to tie into the rest of the Apple desktop products utilizing the corporate Snow White design language incorporated into all product designs since 1986. In addition to adopting the darker colour scheme which co-ordinated with the official corporate look. The innovative look not only unified their entire line. These early series would be the last to utilize the aging Snow White look, the first series of PowerBooks were hugely successful, capturing 40% of all laptop sales. Despite this, the team left to work at Compaq. Apple was unable to ship a 68040-equipped PowerBook until the PowerBook 500 series in 1994, the original PowerBook 100,140, and 170 were replaced by the 145,160, and 180 in 1992. The 160 and 180 having video output allowing them to drive an external monitor, in addition, the PowerBook 180 had a superb-for-the-time active-matrix grayscale display, making it popular with the Mac press. In 1993, the PowerBook 165c was the first PowerBook with a color screen, in 1994, the last true member of the 100-series form factor introduced was the PowerBook 150, targeted at value-minded consumers and students. The PowerBook 190, released in 1995, bears no resemblance to the rest of the PowerBook 100 series, however, like the 190, the 150 also used the 5300 IDE-based logic-board architecture. From the 100s 68000 processor, to the 190s 68LC040 processor, in 1992 Apple released a hybrid portable/desktop computer, the PowerBook Duo, continuing to streamline the subnotebook features introduced with the PowerBook 100. 1994 saw the introduction of the Motorola 68LC040-based PowerBook 500 series and these models of PowerBooks were much sleeker and faster than the 100 series, which they replaced as the mid and high-end models
28.
Macworld
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Macworld is a web site dedicated to products and software of Apple Inc. published by Mac Publishing, which is headquartered in San Francisco, California. It started life as a print magazine in 1984 and had the largest audited circulation of Macintosh-focused magazines in North America, more than double its nearest competitor, Macworld was founded by David Bunnell and Andrew Fluegelman. In 1999, the company also purchased the online publication MacCentral Online. In late 2001 International Data Group bought out Ziff-Davis share of Mac Publishing, making it a wholly owned subsidiary of IDG, the magazine was published in many countries, either by other IDG subsidiaries or by outside publishers who have licensed the brand name and its content. These editions included Australia, Germany, Italy, Spain, Sweden, Turkey, the United Kingdom and its content was also incorporated into a number of other IDG publications. In addition to publishing a print magazine, Macworld also operates numerous web sites, including Macworld, Playlist, MacUser. Every year, Macworld uses its expertise in technology to find the best device in each category in the market, the Macworld Podcast is a weekly podcast published by Macworld, a magazine and web site devoted to Apples Macintosh computers. It was formally hosted by Macworld Senior Editor Chris Breen, and consists mostly of interviews with Macworld editors, Macworld editorial director Jason Snell is a frequent guest and occasional guest host. The programs original host was Cyrus Farivar, the Macworld Podcast began life on April 26,2005 as the Geek Factor Podcast, but was upgraded into the official Macworld Podcast with its fifth installment, in August 2005. Its current hosts as of August 2015 are Glenn Fleishman and Susie Ochs, Macworld Australia Macworld Macworld France Macworld UK Macwelt Macworld Italia Macworld MacWorld Macworld Macworld Macworld
29.
Texas Instruments
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Texas Instruments Inc. is an American technology company that designs and manufactures semiconductors, which it sells to electronics designers and manufacturers globally. Headquartered in Dallas, Texas, United States, TI is one of the top ten semiconductor companies worldwide, Texas Instrumentss focus is on developing analog chips and embedded processors, which accounts for more than 85% of their revenue. TI also produces TI digital light processing technology and education technology products including calculators, microcontrollers, to date, TI has more than 43,000 patents worldwide. TI produced the worlds first commercial silicon transistor in 1950, Jack Kilby invented the integrated circuit in 1958 while working at TIs Central Research Labs. TI also invented the hand-held calculator in 1967, and introduced the first single-chip microcontroller in 1970, in 1987, TI invented the digital light processing device, which serves as the foundation for the companys award-winning DLP technology and DLP Cinema. In 1990, TI came out with the popular TI-81 calculator which made them a leader in the calculator industry. In 1997, its business was sold to Raytheon, which allowed TI to strengthen its focus on digital solutions. Texas Instruments was founded by Cecil H. Green, J. Erik Jonsson, Eugene McDermott, McDermott was one of the original founders of Geophysical Service Inc. in 1930. McDermott, Green, and Jonsson were GSI employees who purchased the company in 1941, in November,1945, Patrick Haggerty was hired as general manager of the Laboratory and Manufacturing division, which focused on electronic equipment. By 1951, the L&M division, with its contracts, was growing faster than GSIs Geophysical division. The company was reorganized and initially renamed General Instruments Inc, because there already existed a firm named General Instrument, the company was renamed Texas Instruments that same year. From 1956 to 1961, Fred Agnich of Dallas, later a Republican member of the Texas House of Representatives, was the Texas Instruments president, Geophysical Service, Inc. became a subsidiary of Texas Instruments. Early in 1988 most of GSI was sold to the Halliburton Company, in 1930, J. Clarence Karcher and Eugene McDermott founded Geophysical Service, an early provider of seismic exploration services to the petroleum industry. In 1939, the company reorganized as Coronado Corp. an oil company with Geophysical Service Inc, on December 6,1941, McDermott along with three other GSI employees, J. Erik Jonsson, Cecil H. Green, and H. B. During World War II, GSI expanded their services to include electronics for the U. S. Army, Signal Corps, in 1951, the company changed its name to Texas Instruments, GSI becoming a wholly owned subsidiary of the new company. Texas Instruments also continued to manufacture equipment for use in the seismic industry, after selling GSI, TI finally sold the company to Halliburton in 1988, at which point GSI ceased to exist as a separate entity. Texas Instruments entered the electronics market in 1942 with submarine detection equipment. During the early 1980s, Texas Instruments instituted a quality program which included Juran training, as well as promoting statistical process control, Taguchi methods and Design for Six Sigma
30.
Motorola 68000
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The Motorola 68000 is a 32-bit CISC microprocessor with a 16-bit external data bus, designed and marketed by Motorola Semiconductor Products Sector. After 38 years in production, the 68000 architecture is still in use, the 68000 grew out of the MACSS project, begun in 1976 to develop an entirely new architecture without backward compatibility. It would be a higher-power sibling complementing the existing 8-bit 6800 line rather than a compatible successor, in the end, the 68000 did retain a bus protocol compatibility mode for existing 6800 peripheral devices, and a version with an 8-bit data bus was produced. However, the designers focused on the future, or forward compatibility. For instance, the CPU registers are 32 bits wide, though few self-contained structures in the processor itself operate on 32 bits at a time. The MACSS team drew heavily on the influence of minicomputer processor design, such as the PDP-11 and VAX systems, in the mid 1970s, the 8-bit microprocessor manufacturers raced to introduce the 16-bit generation. National Semiconductor had been first with its IMP-16 and PACE processors in 1973–1975, Intel had worked on their advanced 16/32-bit Intel iAPX432 since 1975 and their Intel 8086 since 1976. Arriving late to the 16-bit arena afforded the new processor more transistors, 32-bit macroinstructions, the original MC68000 was fabricated using an HMOS process with a 3.5 µm feature size. Formally introduced in September 1979, Initial samples were released in February 1980, Initial speed grades were 4,6, and 8 MHz.10 MHz chips became available during 1981, and 12.5 MHz chips by June 1982. The 16.67 MHz 12F version of the MC68000, the fastest version of the original HMOS chip, was not produced until the late 1980s, tom Gunter, retired Corporate Vice President at Motorola, is known as the Father of the 68000. The 68000 was used in Microsoft Xenix systems as well as an early NetWare Unix-based Server, the 68000 was used in the first generation of desktop laser printers including the original Apple Inc. In 1982, the 68000 received an update to its ISA allowing it to virtual memory and to conform to the Popek. The updated chip was called the 68010, a further extended version which exposed 31 bits of the address bus was also produced, in small quantities, as the 68012. To support lower-cost systems and control applications with smaller sizes, Motorola introduced the 8-bit compatible MC68008. This was a 68000 with an 8-bit data bus and an address bus. After 1982, Motorola devoted more attention to the 68020 and 88000 projects, several other companies were second-source manufacturers of the HMOS68000. These included Hitachi, who shrank the size to 2.7 µm for their 12.5 MHz version, Mostek, Rockwell, Signetics, Thomson/SGS-Thomson. Toshiba was also a maker of the CMOS 68HC000
31.
CPU cache
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Cache memory makes use of the fast technology SRAM, against a slower MM DRAM, connected directly to the processor. The term cache is derived from the French and refers to a place one can hide something. This term has many meanings depending on the context, examples are, disk cache, TLB, branch prediction cache, branch history table, Branch Address Cache, trace cache, that are physical memories. Others are handled by the software, to store data in reserved MM space. Note – CPU cache is a term and rarely or wrongly used in both literature and in industrial environment. For instance, in the US patents documents relating to the cache, the term CPU cache is used in less of 2% of the documents against to the Cache Memory and the Memory Cache. Cache general definition The Cache is a memory that stores data, in silent mode to upper level of utilization. In MM read operation, the controller first of all checks if the data is stored in cache. In case of match the data is fastly and directly supplied from the cache to the processor without involving the MM.3, else the data is read from MM. A cache stores only a subset of MM data – the most recent-used MRU, Data read from MM are temporary stored in cache. If the processor requires the data, this is supplied by the cache. The cache is effective because short instruction loops and routines are a common program structure, spatial locality - If a data is referenced, it is very likely that nearby data will be accessed soon. Instructions and data are transferred from MM to the cache in fixed blocks, Cache line size is in the range of 4 to 512 bytes so that more than one processing data is stored in each cache entry. After a first MM access, all cache line data are available in cache, next instruction usually comes from the next memory location. Data is usually structured and data in these structures normally are stored in memory locations. Large lines size increase the spatial locality but increase also the number of invalidated data in case of line replacement, Cache efficiency is measured in terms of Hit Rate. Hit Rate represents the percentage of Hits compared to the number of cache accesses. The opposite of Hit is called Miss The cache efficiency depends by several elements, cache size, line size, type and cache architecture, a good figure of the cache efficiency, for business applications, may be in the range of 80-95 % of hit
32.
Mask (computing)
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In computer science, a mask is data that is used for bitwise operations, particularly in a bit field. Using a mask, multiple bits in a byte, nibble, word can be set either on, to turn certain bits on, the bitwise OR operation can be used, following the principle that Y OR1 =1 and Y OR0 = Y. Therefore, to make sure a bit is on, OR can be used with a 1, to leave a bit unchanged, OR is used with a 0. Example, Masking on the higher nibble the lower nibble unchanged,1001010110100101 OR1111000011110000 =1111010111110101 More often, in practice, bits that are to be ignored are masked off rather than masked on. There is no way to change a bit from on to off using the OR operation, when a value is ANDed with a 1, the result is simply the original value, as in, Y AND1 = Y. However, ANDing a value with 0 is guaranteed to return a 0, to leave the other bits alone, use AND with 1. Example, Masking off the higher nibble the lower nibble unchanged,1001010110100101 AND0000111100001111 =0000010100000101 It is possible to use bitmasks to easily check the state of individual bits regardless of the other bits. To do this, turning off all the other using the bitwise AND is done as discussed above. If it is equal to 0, then the bit was off, what makes this convenient is that it is not necessary to figure out what the value actually is, just that it is not 0. Example, Querying the status of the 4th bit 1001110110010101 AND0000100000001000 =0000100000000000 So far the article has covered how to turn bits on and turn bits off, but not both at once. Sometimes it does not really matter what the value is, and this can be achieved using the XOR operation. XOR returns 1 if and only if an odd number of bits are 1, therefore, if two corresponding bits are 1, the result will be a 0, but if only one of them is 1, the result will be 1. Therefore inversion of the values of bits is done by XORing them with a 1, if the original bit was 1, it returns 1 XOR1 =0. If the original bit was 0 it returns 0 XOR1 =1, also note that XOR masking is bit-safe, meaning that it will not affect unmasked bits because Y XOR0 = Y, just like an OR. For example, in the graphics API OpenGL, there is a command and it can clear up to four buffers, so the API authors could have had it take four arguments. But then a call to it would look like which is not very descriptive, for example, an implementation of glClear might look like, The advantage to this approach is that function argument overhead is decreased. Since the minimum size is one byte, separating the options into separate arguments would be wasting seven bits per argument. Instead, functions typically accept one or more 32-bit integers, with up to 32 option bits in each, while elegant, in the simplest implementation this solution is not type-safe
33.
Software bug
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A software bug is an error, flaw, failure or fault in a computer program or system that causes it to produce an incorrect or unexpected result, or to behave in unintended ways. Most bugs arise from mistakes and errors made in either a source code or its design, or in components. A few are caused by compilers producing incorrect code, a program that contains a large number of bugs, and/or bugs that seriously interfere with its functionality, is said to be buggy. Bugs trigger errors that may have ripple effects, Bugs may have subtle effects or cause the program to crash or freeze the computer. Others qualify as security bugs and might, for example, enable a user to bypass access controls in order to obtain unauthorized privileges. Bugs in code that controls the Therac-25 radiation therapy machine were directly responsible for patient deaths in the 1980s. In 1996, the European Space Agencys US$1 billion prototype Ariane 5 rocket had to be destroyed less than a minute after launch due to a bug in the guidance computer program. In June 1994, a Royal Air Force Chinook helicopter crashed into the Mull of Kintyre, for instance, Thomas Edison wrote the following words in a letter to an associate in 1878, It has been just so in all of my inventions. The Middle English word bugge is the basis for the terms bugbear and bugaboo, baffle Ball, the first mechanical pinball game, was advertised as being free of bugs in 1931. Problems with military gear during World War II were referred to as bugs, isaac Asimov uses the term bug to relate to issues with a robot in his short story Catch That Rabbit, published in 1944, and included in his well-known collection of short stories I, Robot. From page 1 of Catch That Rabbit, U. S, robots had to get the bugs out of the multiple robot, and there were plenty of bugs, and there are always at least half a dozen bugs left for the field-testing. The term bug was used in an account by computer pioneer Grace Hopper, operators traced an error in the Mark II to a moth trapped in a relay, coining the term bug. This bug was carefully removed and taped to the log book, stemming from the first bug, today we call errors or glitches in a program a bug. Hopper did not find the bug, as she readily acknowledged, the date in the log book was September 9,1947. Hopper loved to recount the story and this log book, complete with attached moth, is part of the collection of the Smithsonian National Museum of American History. The related term debug also appears to predate its usage in computing, an analysing process must equally have been performed in order to furnish the Analytical Engine with the necessary operative data, and that herein may also lie a possible source of error. Granted that the mechanism is unerring in its processes, the cards may give it wrong orders. The report highlights the need for reform in the field of software vulnerability discovery, government researchers, companies, and cyber security experts are the people who typically discover software flaws
34.
Emulator
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In computing, an emulator is hardware or software that enables one computer system to behave like another computer system. An emulator typically enables the host system to run software or use peripheral devices designed for the guest system, emulation refers to the ability of a computer program in an electronic device to emulate another program or device. Many printers, for example, are designed to emulate Hewlett-Packard LaserJet printers because so much software is written for HP printers. If a non-HP printer emulates an HP printer, any software written for a real HP printer will also run in the non-HP printer emulation and produce equivalent printing. Since at least the 1990s until today, some video game enthusiasts use emulators to play 1980s arcade games using the original 1980s programming code, a hardware emulator is an emulator which takes the form of a hardware device. In a theoretical sense, the Church-Turing thesis implies that any operating environment can be emulated within any other environment. However, in practice, it can be difficult, particularly when the exact behavior of the system to be emulated is not documented and has to be deduced through reverse engineering. Emulation is a strategy in digital preservation to combat obsolescence, emulation addresses the original hardware and software environment of the digital object, and recreates it on a current machine. The emulator allows the user to have access to any kind of application or operating system on a current platform and he further states that this should not only apply to out of date systems, but also be upwardly mobile to future unknown systems. Potentially better graphics quality than original hardware, potentially additional features original hardware didnt have. Emulators maintain the look, feel, and behavior of the digital object. Despite the original cost of developing an emulator, it may prove to be the more cost efficient solution over time, many emulators have already been developed and released under GNU General Public License through the open source environment, allowing for wide scale collaboration. Emulators allow software exclusive to one system to be used on another, for example, a PlayStation 2 exclusive video game could be played on a PC using an emulator. This is especially useful when the system is difficult to obtain. Copyright laws are not yet in effect to address saving the documentation and these protections make it more difficult to design emulators, since they must be accurate enough to avoid triggering the protections, whose effects may not be obvious. Emulators require better hardware than the system has. Because of its use of digital formats, new media art relies heavily on emulation as a preservation strategy. The paradox is that the emulation and the emulator have to be made to work on future computers, emulation techniques are commonly used during the design and development of new systems
35.
CMOS
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Complementary metal–oxide–semiconductor, abbreviated as CMOS /ˈsiːmɒs/, is a technology for constructing integrated circuits. CMOS technology is used in microprocessors, microcontrollers, static RAM, CMOS technology is also used for several analog circuits such as image sensors, data converters, and highly integrated transceivers for many types of communication. In 1963, while working for Fairchild Semiconductor, Frank Wanlass patented CMOS, CMOS is also sometimes referred to as complementary-symmetry metal–oxide–semiconductor. Two important characteristics of CMOS devices are high noise immunity and low power consumption. Since one transistor of the pair is always off, the series combination draws significant power only momentarily during switching between on and off states, CMOS also allows a high density of logic functions on a chip. It was primarily for this reason that CMOS became the most used technology to be implemented in VLSI chips, aluminium was once used but now the material is polysilicon. Other metal gates have made a comeback with the advent of high-k dielectric materials in the CMOS process, as announced by IBM and Intel for the 45 nanometer node and beyond. CMOS refers to both a style of digital circuitry design and the family of processes used to implement that circuitry on integrated circuits. CMOS circuitry dissipates less power than logic families with resistive loads, since this advantage has increased and grown more important, CMOS processes and variants have come to dominate, thus the vast majority of modern integrated circuit manufacturing is on CMOS processes. As of 2010, CPUs with the best performance per watt each year have been CMOS static logic since 1976, CMOS circuits use a combination of p-type and n-type metal–oxide–semiconductor field-effect transistor to implement logic gates and other digital circuits. CMOS always uses all enhancement-mode MOSFETs, CMOS circuits are constructed in such a way that all PMOS transistors must have either an input from the voltage source or from another PMOS transistor. Similarly, all NMOS transistors must have either an input from ground or from another NMOS transistor, the composition of a PMOS transistor creates low resistance between its source and drain contacts when a low gate voltage is applied and high resistance when a high gate voltage is applied. On the other hand, the composition of an NMOS transistor creates high resistance between source and drain when a low voltage is applied and low resistance when a high gate voltage is applied. CMOS accomplishes current reduction by complementing every nMOSFET with a pMOSFET, a high voltage on the gates will cause the nMOSFET to conduct and the pMOSFET to not conduct, while a low voltage on the gates causes the reverse. This arrangement greatly reduces power consumption and heat generation, however, during the switching time, both MOSFETs conduct briefly as the gate voltage goes from one state to another. This induces a brief spike in consumption and becomes a serious issue at high frequencies. The image on the right shows what happens when an input is connected to both a PMOS transistor and an NMOS transistor, when the voltage of input A is low, the NMOS transistors channel is in a high resistance state. This limits the current that can flow from Q to ground, the PMOS transistors channel is in a low resistance state and much more current can flow from the supply to the output
36.
Chip carrier
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In electronics, a chip carrier is one of several kinds of surface mount technology packages for integrated circuits. Connections are made on all four edges of a package, Compared to the internal cavity for mounting the integrated circuit. Chip carriers may have either J-shaped metal leads for connections by solder or by a socket, if the leads extend beyond the package, the preferred description is flat pack. Chip carriers are smaller than dual in-line packages and since they use all four edges of the package can have a pin count. Chip carriers may be made of ceramic or plastic, some forms of chip carrier package are standardized in dimensions and registered with trade industry associations such as JEDEC. Other forms are proprietary to one or two manufacturers, sometimes the term chip carrier is used to refer generically to any package for an integrated circuit. It is a reduced cost evolution of the ceramic chip carrier. A premolded PLCC was originally released in 1976, but did not see much market adoption, texas Instruments later released a postmolded variant that was soon adopted by most major semiconductor companies. The PLCC utilizes a J-lead with pin spacings of 0.05, the metal strip forming the lead is wrapped around and under the edge of the package, resembling the letter J in cross-section. Lead counts range from 20 to 84, PLCC packages can be square or rectangular. Body widths range from 0.35 to 1.15, the PLCC “J” Lead configuration requires less board space versus equivalent gull leaded components, which have flat leads that extend out perpendicularly to the narrow edge of the package. The PLCC is preferred over DIP style chip carriers when lead counts exceed 40 pins due to the PLCCs more efficient use of surface area. The heatspreader versions are identical in form factor to the standard non-heatspreader versions, both versions are JEDEC compliant in all respects. The heatspreader versions give the designer greater latitude in thermally enhanced board level. RoHs compliant, lead-free & green material sets are now qualified standards, a PLCC circuit may either be installed in a PLCC socket or surface-mounted. PLCC sockets may in turn be surface mounted, or use through-hole technology, using a PLCC socket may be necessary in situations where the device requires stand-alone programming, such as some flash memory devices. Some through-hole sockets are designed for prototyping with wire wrapping, a specialized tool called a PLCC extractor facilitates the removal of a PLCC from a socket. This package is used for a wide variety of device types
37.
Pin grid array
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A pin grid array, often abbreviated PGA, is a type of integrated circuit packaging. In a PGA, the package is square or rectangular, the pins are commonly spaced 2.54 mm apart, and may or may not cover the entire underside of the package. PGAs are often mounted on printed circuit boards using the through hole method or inserted into a socket, pGAs allow for more pins per integrated circuit than older packages such as dual in-line package. Plastic pin grid array packaging was used by Intel for late model Mendocino core Celeron processors based on Socket 370, some pre-Socket 8 processors also used a similar form factor, although they were not officially referred to as PPGA. A flip-chip pin grid array is a form of pin grid array in which the die faces downwards on the top of the substrate with the back of the die exposed and this allows the die to have a more direct contact with the heatsink or other cooling mechanism. The FC-PGA was introduced by Intel with the Coppermine core Pentium III and Celeron processors based on Socket 370, FC-PGA processors fit into zero insertion force Socket 370 and Socket 478-based motherboard sockets, similar packages have also been used by AMD. It is still used today for mobile Intel processors, the Staggered pin grid array is used by Intel processors based on Socket 5 and Socket 7. Socket 8 used a partial SPGA layout on half the processor and it consists of two square arrays of pins, offset in both directions by half the minimum distance between pins in one of the arrays. Put differently, within a square boundary the pins form a square lattice. There is generally a section in the center of the package without any pins, SPGA packages are usually used by devices that require a higher pin density than what a PGA can provide, such as microprocessors. A ceramic pin grid array is a type of packaging used by integrated circuits and this type of packaging uses a ceramic substrate with pins arranged in a pin grid array. Some CPUs that use CPGA packaging are the AMD Socket A Athlons, a CPGA was used by AMD for Athlon and Duron processors based on Socket A, as well as some AMD processors based on Socket AM2 and Socket AM2+. While similar form factors have been used by manufacturers, they are not officially referred to as CPGA. This type of packaging uses a ceramic substrate with pins arranged in an array, a Stud Grid Array is a short-pinned pin grid array chip scale package for use in Surface-mount technology. The Polymer Stud Grid Array or Plastic Stud Grid Array was developed jointly by the Interuniversity Microelectronics Centre and Laboratory for Production Technology and it is used in the G1, G2, and G3 sockets. What the Hell is… a flip-chip, XSERIES335 XEON DP-2. 4G512 MB
38.
Quad Flat Package
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A QFP or Quad Flat Package is a surface mount integrated circuit package with gull wing leads extending from each of the four sides. Socketing such packages is rare and through-hole mounting is not possible, versions ranging from 32 to 304 pins with a pitch ranging from 0.4 to 1.0 mm are common. Other special variants include low profile QFP and thin QFP, the QFP component package type became common in Europe and United States during the early nineties, even though it has been used in Japanese consumer electronics since the seventies. It is often mixed with hole mounted, and sometimes socketed, a package related to QFP is PLCC which is similar but has pins with larger pitch,1.27 mm, curved up underneath a thicker body to simplify socketing. It is commonly used for NOR Flash memories and other programmable components, the quad flat-pack has connections only around the periphery of the package. To increase the number of pins, the spacing was decreased from 50 mil to 20, however, this close lead spacing made solder bridges more likely and put higher demands on the soldering process and alignment of parts during assembly. The basic form is a rectangular body with leads on four sides. These differ usually only in number, pitch, dimensions. A clear variation is Bumpered Quad Flat Package with extensions at the four corners to protect the leads against mechanical damage before the unit is soldered, heat sink Quad Flat Package, Heatsink Very-thin Quad Flat-pack No-leads is a package with no component leads extending from the IC. Pads are spaced along the sides of the IC with an exposed DIE that can be used as ground, a thin quad flat pack provides the same benefits as the metric QFP, but is thinner. Regular QFP are 2.0 to 3.8 mm thick depending on size, lead counts range from 32 to 176. Body sizes range from 5 mm x 5 mm to 20 x 20 mm, copper lead-frames are used in TQFPs. Lead pitches available for TQFPs are 0.4 mm,0.5 mm,0.65 mm,0.8 mm, PQFP, or plastic quad flat pack, is a type of QFP, as is the thinner TQFP package. PQFP packages can vary in thickness from 2.0 mm to 3.8 mm, a Low-profile Quad Flat Package is a surface mount integrated circuit package format with component leads extending from each of the four sides. Pins are numbered counter-clockwise from the index dot, spacing between pins can vary, common spacings are 0.4,0.5,0.65 and 0.80 mm intervals. Some QFP packages have an Exposed Pad, the exposed pad is an extra pad underneath or on top of the QFP that may act as a ground connection and/or as a heat sink for the package. The pad is typically 10 or more mm², and with the pad soldered down onto the ground plane and this exposed pad also gives a solid ground connection. These type of QFP packages often have a -EP suffix, or they have an odd number of leads
39.
Instruction set architecture
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An ISA includes a specification of the set of opcodes, and the native commands implemented by a particular processor. An instruction set architecture is distinguished from a microarchitecture, which is the set of design techniques used, in a particular processor. Processors with different microarchitectures can share a common instruction set, for example, the Intel Pentium and the AMD Athlon implement nearly identical versions of the x86 instruction set, but have radically different internal designs. The concept of an architecture, distinct from the design of a machine, was developed by Fred Brooks at IBM during the design phase of System/360. Prior to NPL, the companys computer designers had been free to honor cost objectives not only by selecting technologies, the SPREAD compatibility objective, in contrast, postulated a single architecture for a series of five processors spanning a wide range of cost and performance. In addition, these virtual machines execute less frequently used code paths by interpretation, transmeta implemented the x86 instruction set atop VLIW processors in this fashion. A complex instruction set computer has many specialized instructions, some of which may only be used in practical programs. Theoretically important types are the instruction set computer and the one instruction set computer. Another variation is the very long instruction word where the processor receives many instructions encoded and retrieved in one instruction word, machine language is built up from discrete statements or instructions. Examples of operations common to many instruction sets include, Set a register to a constant value. Copy data from a location to a register, or vice versa. Used to store the contents of a register, result of a computation, often called load and store operations. Read and write data from hardware devices, add, subtract, multiply, or divide the values of two registers, placing the result in a register, possibly setting one or more condition codes in a status register. Increment, decrement in some ISAs, saving operand fetch in trivial cases, perform bitwise operations, e. g. taking the conjunction and disjunction of corresponding bits in a pair of registers, taking the negation of each bit in a register. Floating-point instructions for arithmetic on floating-point numbers, branch to another location in the program and execute instructions there. Conditionally branch to another if a certain condition holds. Call another block of code, while saving the location of the instruction as a point to return to. Load/store data to and from a coprocessor, or exchanging with CPU registers, processors may include complex instructions in their instruction set
40.
Wayback Machine
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The Internet Archive launched the Wayback Machine in October 2001. It was set up by Brewster Kahle and Bruce Gilliat, and is maintained with content from Alexa Internet, the service enables users to see archived versions of web pages across time, which the archive calls a three dimensional index. Since 1996, the Wayback Machine has been archiving cached pages of websites onto its large cluster of Linux nodes and it revisits sites every few weeks or months and archives a new version. Sites can also be captured on the fly by visitors who enter the sites URL into a search box, the intent is to capture and archive content that otherwise would be lost whenever a site is changed or closed down. The overall vision of the machines creators is to archive the entire Internet, the name Wayback Machine was chosen as a reference to the WABAC machine, a time-traveling device used by the characters Mr. Peabody and Sherman in The Rocky and Bullwinkle Show, an animated cartoon. These crawlers also respect the robots exclusion standard for websites whose owners opt for them not to appear in search results or be cached, to overcome inconsistencies in partially cached websites, Archive-It. Information had been kept on digital tape for five years, with Kahle occasionally allowing researchers, when the archive reached its fifth anniversary, it was unveiled and opened to the public in a ceremony at the University of California, Berkeley. Snapshots usually become more than six months after they are archived or, in some cases, even later. The frequency of snapshots is variable, so not all tracked website updates are recorded, Sometimes there are intervals of several weeks or years between snapshots. After August 2008 sites had to be listed on the Open Directory in order to be included. As of 2009, the Wayback Machine contained approximately three petabytes of data and was growing at a rate of 100 terabytes each month, the growth rate reported in 2003 was 12 terabytes/month, the data is stored on PetaBox rack systems manufactured by Capricorn Technologies. In 2009, the Internet Archive migrated its customized storage architecture to Sun Open Storage, in 2011 a new, improved version of the Wayback Machine, with an updated interface and fresher index of archived content, was made available for public testing. The index driving the classic Wayback Machine only has a bit of material past 2008. In January 2013, the company announced a ground-breaking milestone of 240 billion URLs, in October 2013, the company announced the Save a Page feature which allows any Internet user to archive the contents of a URL. This became a threat of abuse by the service for hosting malicious binaries, as of December 2014, the Wayback Machine contained almost nine petabytes of data and was growing at a rate of about 20 terabytes each week. Between October 2013 and March 2015 the websites global Alexa rank changed from 162 to 208, in a 2009 case, Netbula, LLC v. Chordiant Software Inc. defendant Chordiant filed a motion to compel Netbula to disable the robots. Netbula objected to the motion on the ground that defendants were asking to alter Netbulas website, in an October 2004 case, Telewizja Polska USA, Inc. v. Echostar Satellite, No.02 C3293,65 Fed. 673, a litigant attempted to use the Wayback Machine archives as a source of admissible evidence, Telewizja Polska is the provider of TVP Polonia and EchoStar operates the Dish Network
