1.
Home computer
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Home computers were a class of microcomputers entering the market in 1977, and becoming common during the 1980s. They were marketed to consumers as affordable and accessible computers that, however, a home computer often had better graphics and sound than contemporaneous business computers. Their most common uses were playing games, but they were also regularly used for word processing, doing homework. Home computers were usually not electronic kits, home computers were already manufactured in stylish metal or plastic enclosures. There were, however, commercial kits like the Sinclair ZX80 which were home and home-built computers since the purchaser could assemble the unit from a kit. For example, using a typical 1980s home computer as a home automation appliance would require the computer to be powered on at all times. Personal finance and database use required tedious data entry, by contrast, advertisements in the specialty computer press often simply listed specifications. Since most systems shipped with the BASIC programming language included on the system ROM, many users found programming to be a fun and rewarding experience, and an excellent introduction to the world of digital technology. Often the only difference may be the outlet through which they are purchased. Another change from the computer era is that the once-common endeavour of writing ones own software programs has almost vanished from home computer use. As early as 1965, some projects such as Jim Sutherlands ECHO IV explored the possible utility of a computer in the home. In 1969, the Honeywell Kitchen Computer was marketed as a gift item, and would have inaugurated the era of home computing. Computers became affordable for the public in the 1970s due to the mass production of the microprocessor starting in 1971. Early microcomputers such as the Altair 8800 had front-mounted switches and diagnostic lights to control and indicate internal system status, while two early home computers could be bought either in kit form or assembled, most home computers were only sold pre-assembled. The keyboard - a feature lacking on the Altair - was usually built into the case as the motherboard. Ports for plug-in peripheral devices such as a display, cassette tape recorders, joysticks. Usually the manufacturer would sell peripheral devices designed to be compatible with their computers as extra cost accessories, peripherals were not often interchangeable between different brands of home computer, or even between successive models of the same brand. To save the cost of a monitor, the home computer would often connect through an RF modulator to the family TV set
2.
Operating system
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An operating system is system software that manages computer hardware and software resources and provides common services for computer programs. All computer programs, excluding firmware, require a system to function. Operating systems are found on many devices that contain a computer – from cellular phones, the dominant desktop operating system is Microsoft Windows with a market share of around 83. 3%. MacOS by Apple Inc. is in place, and the varieties of Linux is in third position. Linux distributions are dominant in the server and supercomputing sectors, other specialized classes of operating systems, such as embedded and real-time systems, exist for many applications. A single-tasking system can run one program at a time. Multi-tasking may be characterized in preemptive and co-operative types, in preemptive multitasking, the operating system slices the CPU time and dedicates a slot to each of the programs. Unix-like operating systems, e. g. Solaris, Linux, cooperative multitasking is achieved by relying on each process to provide time to the other processes in a defined manner. 16-bit versions of Microsoft Windows used cooperative multi-tasking, 32-bit versions of both Windows NT and Win9x, used preemptive multi-tasking. Single-user operating systems have no facilities to distinguish users, but may allow multiple programs to run in tandem, a distributed operating system manages a group of distinct computers and makes them appear to be a single computer. The development of networked computers that could be linked and communicate with each other gave rise to distributed computing, distributed computations are carried out on more than one machine. When computers in a work in cooperation, they form a distributed system. The technique is used both in virtualization and cloud computing management, and is common in large server warehouses, embedded operating systems are designed to be used in embedded computer systems. They are designed to operate on small machines like PDAs with less autonomy and they are able to operate with a limited number of resources. They are very compact and extremely efficient by design, Windows CE and Minix 3 are some examples of embedded operating systems. A real-time operating system is a system that guarantees to process events or data by a specific moment in time. A real-time operating system may be single- or multi-tasking, but when multitasking, early computers were built to perform a series of single tasks, like a calculator. Basic operating system features were developed in the 1950s, such as resident monitor functions that could run different programs in succession to speed up processing
3.
Digital Research
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Digital Research, Inc. was the company created by Dr. Gary Kildall to market and develop his CP/M operating system and related products. It was the first large company in the microcomputer world. Digital Research was based in Pacific Grove, California, the companys operating systems, starting with CP/M for 8080/Z80-based microcomputers, were the de facto standard of their era, as MS-DOS and Microsoft Windows came later. DRs product suite included the original CP/M and its various offshoots, DR-DOS which was a MS-DOS compatible version of CP/M, and MP/M, the first 16-bit system was CP/M-86, which was to be unsuccessful in competition with MS-DOS. There followed Concurrent CP/M, a version of the multi-tasking MP/M-86 featuring virtual consoles from which applications could be launched to run concurrently. Successive revisions of this system, which gradually supported MS-DOS applications, in May 1983 Digital Research announced that it would offer PC DOS versions of all of its languages and utilities. It remained influential, with $45 million in 1983 sales making Digital Research the fourth-largest microcomputer software company, jerry Pournelle warned later that year, however, that Many people of stature seem to have left or are leaving Digital Research. DR had better get its act together, in 1985, soon after the introduction of the Intel 80286, Digital Research introduced a real-time system, initially called Concurrent DOS286 and subsequently FlexOS. This exploited the greater memory addressing capability of the new CPU to provide a more flexible multi-tasking environment, there was a small but powerful set of system APIs, each with a synchronous and an asynchronous variant. Pipes were supported, and all named resources could be aliased by setting Environment variables and this system was to enjoy enduring favour in point-of-sale systems and was adopted as the basis for IBM4680 OS and IBM4690 OS. Digital Research was purchased by Novell in 1991, primarily for Novell to gain access to the operating system line. Digital Research produced a selection of programming language compilers and interpreters for their OS-supported platforms, including C, Pascal, COBOL, Forth, PL/I, PL/M, CBASIC, BASIC, and Logo. They also produced a version of the GKS graphics standard called GSX. Less known are their application programs, limited largely to the GSX-based DR DRAW, Dr. Halo for DOS, at the time IBM Personal Computer was being developed, Digital Researchs CP/M was the dominant operating system of the day. IBM asked DR to supply a version of CP/M written for the Intel 8086 microprocessor as the operating system for the PC. Digital Research, uneasy about making such an agreement with IBM, Microsoft seized this opportunity to supply an OS, in addition to other software for the new IBM PC. When the IBM PC arrived in late 1981, it came with PC DOS, which was developed from 86-DOS, by mid-1982, it was marketed as MS-DOS for use in hardware-compatible non-IBM computers. This one decision resulted in Microsoft becoming the name in computer software
4.
CP/M
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Initially confined to single-tasking on 8-bit processors and no more than 64 kilobytes of memory, later versions of CP/M added multi-user variations and were migrated to 16-bit processors. The combination of CP/M and S-100 bus computers was loosely patterned on the MITS Altair and this computer platform was widely used in business through the late 1970s and into the mid-1980s. CP/M increased the size for both hardware and software by greatly reducing the amount of programming required to install an application on a new manufacturers computer. An important driver of innovation was the advent of low-cost microcomputers running CP/M, as independent programmers and hackers bought them. CP/M was displaced by MS-DOS soon after the 1981 introduction of the IBM PC, manufacturers of CP/M-compatible systems customized portions of the operating system for their own combination of installed memory, disk drives, and console devices. CP/M would also run on based on the Zilog Z80 processor since the Z80 was compatible with 8080 code. CP/M used the 7-bit ASCII set, the other 128 characters made possible by the 8-bit byte were not standardized. For example, one Kaypro used them for Greek characters, WordStar used the 8th bit as an end-of-word marker. The BIOS and BDOS were memory-resident, while the CCP was memory-resident unless overwritten by an application, a number of transient commands for standard utilities were also provided. The transient commands resided in files with the extension. COM on disk, the BIOS directly controlled hardware components other than the CPU and main memory. It contained functions such as input and output and the reading and writing of disk sectors. The BDOS implemented the CP/M file system and some input/output abstractions on top of the BIOS, the CCP took user commands and either executed them directly or loaded and started an executable file of the given name. Third-party applications for CP/M were also essentially transient commands, the BDOS, CCP and standard transient commands were the same in all installations of a particular revision of CP/M, but the BIOS portion was always adapted to the particular hardware. Adding memory to a computer, for example, meant that the CP/M system had to be reinstalled with an updated BIOS capable of addressing the additional memory, a utility was provided to patch the supplied BIOS, BDOS and CCP to allow them to be run from higher memory. Once installed, the system was stored in reserved areas at the beginning of any disk which would be used to boot the system. On start-up, the bootloader would load the system from the disk in drive A. By modern standards CP/M was primitive, owing to the constraints on program size. With version 1.0 there was no provision for detecting a changed disk, if a user changed disks without manually rereading the disk directory the system would write on the new disk using the old disks directory information, ruining the data stored on the disk
5.
Central processing unit
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The computer industry has used the term central processing unit at least since the early 1960s. The form, design and implementation of CPUs have changed over the course of their history, most modern CPUs are microprocessors, meaning they are contained on a single integrated circuit chip. An IC that contains a CPU may also contain memory, peripheral interfaces, some computers employ a multi-core processor, which is a single chip containing two or more CPUs called cores, in that context, one can speak of such single chips as sockets. Array processors or vector processors have multiple processors that operate in parallel, there also exists the concept of virtual CPUs which are an abstraction of dynamical aggregated computational resources. Early computers such as the ENIAC had to be rewired to perform different tasks. Since the term CPU is generally defined as a device for software execution, the idea of a stored-program computer was already present in the design of J. Presper Eckert and John William Mauchlys ENIAC, but was initially omitted so that it could be finished sooner. On June 30,1945, before ENIAC was made, mathematician John von Neumann distributed the paper entitled First Draft of a Report on the EDVAC and it was the outline of a stored-program computer that would eventually be completed in August 1949. EDVAC was designed to perform a number of instructions of various types. Significantly, the programs written for EDVAC were to be stored in high-speed computer memory rather than specified by the wiring of the computer. This overcame a severe limitation of ENIAC, which was the considerable time, with von Neumanns design, the program that EDVAC ran could be changed simply by changing the contents of the memory. Early CPUs were custom designs used as part of a larger, however, this method of designing custom CPUs for a particular application has largely given way to the development of multi-purpose processors produced in large quantities. This standardization began in the era of discrete transistor mainframes and minicomputers and has accelerated with the popularization of the integrated circuit. The IC has allowed increasingly complex CPUs to be designed and manufactured to tolerances on the order of nanometers, both the miniaturization and standardization of CPUs have increased the presence of digital devices in modern life far beyond the limited application of dedicated computing machines. Modern microprocessors appear in electronic devices ranging from automobiles to cellphones, the so-called Harvard architecture of the Harvard Mark I, which was completed before EDVAC, also utilized a stored-program design using punched paper tape rather than electronic memory. Relays and vacuum tubes were used as switching elements, a useful computer requires thousands or tens of thousands of switching devices. The overall speed of a system is dependent on the speed of the switches, tube computers like EDVAC tended to average eight hours between failures, whereas relay computers like the Harvard Mark I failed very rarely. In the end, tube-based CPUs became dominant because the significant speed advantages afforded generally outweighed the reliability problems, most of these early synchronous CPUs ran at low clock rates compared to modern microelectronic designs. Clock signal frequencies ranging from 100 kHz to 4 MHz were very common at this time, the design complexity of CPUs increased as various technologies facilitated building smaller and more reliable electronic devices
6.
Zilog Z80
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The Z80 CPU is an 8-bit based microprocessor. It was introduced by Zilog in 1976 as the companys first product. The Z80 was conceived by Federico Faggin in late 1974 and developed by him and his employees at Zilog from early 1975 until March 1976. With the revenue from the Z80, the company built its own chip factories, the Zilog Z80 was a software compatible extension and enhancement of the Intel 8080 and, like it, was mainly aimed at embedded systems. In the early 1980s, the Z80 was the most commonly used CPU of all time, Zilog licensed the Z80 to the US-based Synertek and Mostek, that had helped them with initial production, as well as to a European second source manufacturer, SGS. The design was copied also by several Japanese, East European and Russian manufacturers and this enabled the Z80 to gain acceptance in the world market since large companies like NEC, Toshiba, Sharp, and Hitachi, started to manufacture the device. The Z80 came about when physicist Federico Faggin left Intel at the end of 1974 to found Zilog with Ralph Ungermann, at Fairchild Semiconductor, and later at Intel, Faggin had been working on fundamental transistor and semiconductor manufacturing technology. He also developed the design methodology used for memories and microprocessors at Intel and led the work on the Intel 4004. Masatoshi Shima, the logic and transistor level-designer of the 4004. By March 1976, Zilog had developed the Z80 as well as an accompanying assembler based development system for its customers, and by July 1976, early Z80s were manufactured by Synertek and Mostek, before Zilog had its own manufacturing factory ready, in late 1976. Masatoshi Shima designed most of the microarchitecture as well as the gate and transistor levels of the Z80 CPU, assisted by a number of engineers. CEO Federico Faggin was actually involved in the chip layout work. Faggin worked 80 hours a week in order to meet the tight schedule given by the financial investors, a non maskable interrupt which can be used to respond to power down situations and/or other high priority events. Two separate register files, which could be switched, to speed up response to interrupts such as fast asynchronous event handlers or a multitasking dispatcher. Although they were not intended as extra registers for general code, less hardware required for power supply, clock generation and interface to memory and I/O Single 5-volt power supply. A built-in DRAM refresh mechanism that would otherwise have to be provided by external circuitry, a special reset function which clears only the program counter so that a single Z80 CPU could be used in a development system such as an in-circuit emulator. The Z80 took over from the 8080 and its offspring, the 8085, in the processor market, perhaps a key to the initial success of the Z80 was the built-in DRAM refresh, and other features which allowed systems to be built with fewer support chips. For the original NMOS design, the specified upper frequency limit increased successively from the introductory 2.5 MHz, via the well known 4 MHz
7.
MOS Technology VIC-II
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Succeeding MOSs original VIC, the VIC-II was one of the two chips mainly responsible for the C64s success. The VIC-II chip was designed primarily by Al Charpentier and Charles Winterble at MOS Technology, the idea of adding sprites came from the Texas Instruments TI-99/4A computer and its TMS9918 graphics coprocessor. The idea to support collision detection came from the Mattel Intellivision, the Atari 800 was also mined for desired features. About 3/4 of the surface is used for the sprite functionality. The chip was partly laid out using electronic design automation tools from Applicon, the design was partly debugged by fabricating chips containing small subsets of the design, which could then be tested separately. This was easy since MOS Technology had both its research and development lab and semiconductor plant at the same location, the chip was developed in 5 micrometer technology. The work on the VIC-II was completed in November 1981 while Robert Yannes was simultaneously working on the SID chip, both chips, like the Commodore 64, were finished in time for the Consumer Electronics Show in the first weekend of January 1982. To yield the register numbers as given in data sheets. The VIC-II is programmed by manipulating its 47 control registers, memory mapped to the range $D000–$D02E in the C64 address space, of all these registers,34 deal exclusively with sprite control. The hardware limitation of 8 sprites per scanline could be increased further by letting the sprites flicker rapidly on, mastery of the raster interrupt was essential in order to unleash the VIC-IIs capabilities. Many demos and some games would establish a fixed lock-step between the CPU and the VIC-II so that the VIC registers could be manipulated at exactly the right moment. Most programming of the VIC-II is done with programmable character mode, in power-on default mode, the character ROM is used which contains the PETSCII set. Normally, it can be only by the VIC-II and not the CPU. It is mapped into memory locations $3000–$3FFF and $B000-$BFFF and because of this, by adjusting the bits in $01, the ROM can be mapped into $D000-$DFFF where it becomes visible to the CPU and programmers may copy characters from it to a different location as needed. Up to 256 characters can be accessed by the VIC-II at once, the default character set consists of two groups of 128 characters, the second group merely being an inverse video version of the first group. Each character takes 8 bytes of memory to store, in addition to charsets, the VIC-II also uses 1k for its screen memory. Color RAM is at $D800-$DBFF and cannot be moved from that location and it contains the values for Color 1 of each character. In default hires character mode, the foreground of each character may be set individual per the color RAM, colors 2 and 3 are set by the registers at $D022 and $D023 and are global for all characters
8.
Sprite (computer graphics)
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In computer graphics, a sprite is a two-dimensional bitmap that is integrated into a larger scene. Originally sprites referred to independent objects that are composited together, by hardware and this occurs as each scan line is prepared for the video output device, such as a CRT, without involvement of the main CPU and without the need for a full-screen frame buffer. Sprites can be positioned or altered by setting attributes used during the composition process. Examples of systems with hardware sprites include the Atari 8-bit family, Commodore 64, Nintendo Entertainment System, Sega Genesis, the act of creating sprites is a form of pixel art. It is sometimes referred to as spriting, especially in the hobbyist community, the use of sprites originated with arcade games. The first video game to represent player characters as human player images was Taitos Basketball, Signetics devised the first video/graphics processors capable of generating sprite graphics for home systems. The Signetics 2636 video processors were first used in the 1976 Radofin 1292 Advanced Programmable Video System, the Atari VCS, released in 1977, features a hardware sprite implementation where five graphical objects can be moved independently of the game playfield. The term sprite was not in use at the time, the VCSs sprites are called movable objects in the programming manual, further identified as two players, two missiles, and one ball. These each consist of a row of pixels that are displayed on a scan line. To produce a shape, the sprites single-row bitmap is altered by software from one scanline to the next. Each is the height of the display—a long, thin strip. DMA from a table in memory automatically sets the graphics pattern registers for each scan line, hardware registers control the horizontal position of each player and missile. Vertical motion is achieved by moving the data within a player or missiles strip. The feature was called player/missile graphics by Atari, the Namco Galaxian arcade system board, for the 1979 arcade game Galaxian, featured animated, multi-colored sprites. According to Steve Golson from General Computer Corporation, the stamp was used instead of sprite at the time. The Elektor TV Games Computer was a microcomputer capable of generating sprite graphics. The term sprite was first used in the sense by one of the definers of the Texas Instruments 9918 video display processor. By this time, sprites had advanced to the point where complete two-dimensional shapes could be moved around the screen horizontally and vertically with minimal software overhead, the CPU would instruct the external chips to fetch source images and integrate them into the main screen using direct memory access channels
9.
MOS Technology 8563
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The 8563 Video Display Controller was an integrated circuit produced by MOS Technology. It was used in the Commodore 128 computer to generate an 80-column RGB video display, the DCR models of the C128 used the later and more technically advanced 8568 VDC controller. Originally intended for a planned UNIX-based business computer, Commodore designed the VDC into several prototype machines, of these, only the Commodore 128 ever saw production. Unlike earlier MOS video chips such as the popular VIC-II, the VDC had dedicated video memory,16 kilobytes in the original or flat C128 and 64 kilobytes in the C128DCR and this RAM was not directly accessible by the microprocessor. The 8563 was more difficult to produce than most of the rest of the MOS Technology line, also, there were timing issues with the VDC that would cause indirect load and store operations on its registers to malfunction. Authors Lou Wallace and David Darus later developed the Ultra Hi-Res utility into a commercial package, one of the most popular third-party utilities for the C128, this offered more advanced VDC high-resolution capabilities to a wide audience of programmers. Commodore finally offered complete official documentation on the VDC in the Commodore 128 Programmers Reference Guide, VDC bitmap modes were used extensively in the C128 version of the GEOS operating system. The VDC lacked sprite capabilities, which limited its use in gaming applications, however, it did contain blitting capabilities to autonomously perform small block memory copies within its dedicated video RAM. While the VDC is performing such a copy, the system CPU can continue running code and these functions were used by the C128s screen editor ROM to rapidly scroll or clear screen sections. RGBI output compatible with IBMs CGA video standard,16 or 64 kilobyte address space for display, character shape and display attribute memory. Up to 720×700 pixel video resolution in interlaced mode, other image sizes are possible, depending on programmers needs, such as 640×200 non-interlaced, 640×400 interlaced, etc. 80×25 characters text resolution, other such as 80×50 or 40×25 are possible. Addressing the VDCs internal registers and dedicated video memory must be accomplished by indirect means, first the program must tell the VDC which of its 37 internal registers is to be accessed. Next the program must wait until the VDC is ready for the access, after which a read or write on the selected internal register may be performed
10.
Blitter
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The name comes from the bit blit operation, which stands for bit-block transfer. A typical use for a blitter is the movement of a bitmap, such as windows and fonts in a user interface or sprites. In early computers with raster-graphics output, the buffer was normally held in main memory. For CPUs without caches, this bus requirement for instructions was as significant as data, the 1973 Xerox Alto, where the term bit blit originated, had a bit block transfer instruction implemented in microcode, making it much faster than the same operation written on the CPU. The microcode was implemented by Dan Ingalls, the MS-DOS compatible Mindset contained a custom VLSI chip to move rectangular sections of a bitmap. The hardware handled transparency and eight modes for combining the source, released in 1984, the Mindset was claimed to have graphics up to 50x faster than PCs of the time, but the system was not successful. The Commodore Amiga, released the year, also has a full-featured blitter. The first US patent filing to use the blitter was Personal computer apparatus for block transfer of bit-mapped image data, assigned to Commodore-Amiga. It also performs a 4 operand boolean operation The IBM 8514/A display adapter, introduced with the IBM Personal System/2 computers in April 1987, later models of the Atari ST include a blitter co-processor, which was stylized as the BLiTTER chip. It was introduced on the Mega series, and then supported on most later machines. The short-lived Atari Transputer Workstation contained blitter hardware as part of its Blossom video system, 1982s Robotron,2084 from Williams Electronics includes two blitter chips which allow the game to have up to 80 simultaneously moving objects. Performance was measured at roughly 910 KB/second, the blitter operates on 4-bit pixels. Color 0 is transparent, allowing for non-rectangular shapes, Williams used the same blitters in other games from the same time period, including Sinistar and Joust. The TMS34010, released in 1986, is a general purpose 32-bit processor with additional instructions for manipulating bitmap data. It is optimized for cases that normally take extra processing on the CPU, such as handling transparent pixels, working with non-byte aligned data, and converting between bit depths. The TMS34010 served as both CPU and GPU for a number of games in the late 1980s and early 1990s, including Hard Drivin, Narc, Smash TV, Mortal Kombat, and NBA Jam. Hardware sprites are small bitmaps that can be positioned independently, composited together with the background on-the-fly by the video chip, so no actual modification of the frame buffer occurs. Sprite systems are efficient for moving graphics, typically requiring 1/3 the memory cycles as only image data needed to be fetched
11.
MOS Technology SID
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The MOS Technology 6581/8580 SID is the built-in Programmable Sound Generator chip of Commodores CBM-II, Commodore 64, Commodore 128 and Commodore MAX Machine home computers. It was one of the first sound chips of its kind to be included in a computer prior to the digital sound revolution. Together with the VIC-II graphics chip, the SID was instrumental in making the C64 the best-selling computer in history, patent 4,677,890, which was filed on February 27,1983, and issued on July 7,1987. The patent expired on July 7,2004, the SID was devised by engineer Robert Bob Yannes, who later co-founded the Ensoniq digital synthesizer company. Yannes headed a team that included himself, two technicians and a CAD operator, who designed and completed the chip in five months, Yannes was inspired by previous work in the synthesizer industry and was not impressed by the current state of computer sound chips. Instead, he wanted a high-quality instrument chip, which is the reason why the SID has features like the envelope generator, emphasis during chip design was on high-precision frequency control, and the SID was originally designed to have 32 independent voices, sharing a common oscillator. Another feature that was not incorporated in the design was a frequency look-up table for the most common musical notes. The support for an input pin was a feature Yannes added without asking. The masks were produced in 7-micrometer technology to gain a high yield, the chip, like the first product using it, was finished in time for the Consumer Electronics Show in the first weekend of January 1982. Even though Yannes was partly displeased with the result, his colleague Charles Winterble said, the specifications for the chip were not used as a blueprint. Rather, they were written as the development work progressed, Yannes claims he had a feature-list of which three quarters made it into the final design. This is the reason why some of the specifications for the first version were accidentally incorrect, the later revision was revised to match the specification. For example, the 8580 expanded on the ability to perform a binary AND between two waveforms, something that the 6581 could only do in a limited and unintuitive manner. Another feature that differs between the two revisions is the filter, the 6581 version is far away from the specification, since 6581 and 8580 SID ICs are no longer produced, they have become highly sought after. In late 2007, various defective chips started appearing on eBay as supposedly new, all of these remarked SIDs have a defective filter, but some also have defective channels/noise generators, and some are completely dead. The different filter modes are sometimes combined to produce additional timbres, three attack/decay/sustain/release volume controls, one for each audio oscillator. Oscillator sync for each audio oscillator, two 8-bit A/D converters external audio input random number/modulation generator The SID is a mixed-signal integrated circuit, featuring both digital and analog circuitry. All control ports are digital, while the ports are analog
12.
Electronic oscillator
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An electronic oscillator is an electronic circuit that produces a periodic, oscillating electronic signal, often a sine wave or a square wave. Oscillators convert direct current from a supply to an alternating current signal. They are widely used in electronic devices. Oscillators are often characterized by the frequency of their output signal and this term is typically used in the field of audio synthesizers, to distinguish it from an audio frequency oscillator. An audio oscillator produces frequencies in the range, about 16 Hz to 20 kHz. An RF oscillator produces signals in the frequency range of about 100 kHz to 100 GHz. Oscillators designed to produce a high-power AC output from a DC supply are usually called inverters, there are two main types of electronic oscillator, the linear or harmonic oscillator and the nonlinear or relaxation oscillator. The harmonic, or linear, oscillator produces a sinusoidal output, when the power supply to the amplifier is first switched on, electronic noise in the circuit provides a non-zero signal to get oscillations started. The noise travels around the loop and is amplified and filtered until very quickly it converges on a wave at a single frequency. RC oscillators are used to generate lower frequencies, for example in the audio range. Common types of RC oscillator circuits are the phase shift oscillator, in an LC oscillator circuit, the filter is a tuned circuit consisting of an inductor and capacitor connected together. Charge flows back and forth between the plates through the inductor, so the tuned circuit can store electrical energy oscillating at its resonant frequency. There are small losses in the circuit, but the amplifier compensates for those losses and supplies the power for the output signal. Typical LC oscillator circuits are the Hartley, Colpitts and Clapp circuits, in a crystal oscillator circuit the filter is a piezoelectric crystal. The crystal mechanically vibrates as a resonator, and its frequency of vibration determines the oscillation frequency, crystals have very high Q-factor and also better temperature stability than tuned circuits, so crystal oscillators have much better frequency stability than LC or RC oscillators. Crystal oscillators are the most common type of linear oscillator, used to stabilize the frequency of most radio transmitters, crystal oscillators often use the same circuits as LC oscillators, with the crystal replacing the tuned circuit, the Pierce oscillator circuit is also commonly used. Quartz crystals are generally limited to frequencies of 30 MHz or below, other types of resonator, dielectric resonators and surface acoustic wave devices, are used to control higher frequency oscillators, up into the microwave range. For example, SAW oscillators are used to generate the signal in cell phones
13.
Waveform
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A waveform is the shape and form of a signal such as a wave moving in a physical medium or an abstract representation. In many cases the medium in which the wave propagates does not permit a direct observation of the true form, in these cases, the term waveform refers to the shape of a graph of the varying quantity against time. An instrument called an oscilloscope can be used to represent a wave as a repeating image on a screen. To be more specific, a waveform is depicted by a graph that shows the changes in a signals amplitude over the duration of recording. The amplitude of the signal is measured on the y -axis, most programs show waveforms to give the user a visual aid of what has been recorded. If the waveform is of low or high height, the recording was most likely conducted under conditions with a low or high input volume, respectively. From this example, it follows that the represented by the waveform is affected by both the input signal and conditions under which it is recorded. A periodic waveforms include these while t is time, λ is wavelength, the amplitude of the waveform follows a trigonometric sine function with respect to time. Square wave = { a, mod λ < duty − a and this waveform is commonly used to represent digital information. A square wave of constant period contains odd harmonics that decrease at −6 dB/octave, triangle wave =2 a π arcsin sin 2 π t − ϕ λ. It contains odd harmonics that decrease at −12 dB/octave, sawtooth wave =2 a π arctan tan 2 π t − ϕ2 λ. This looks like the teeth of a saw, found often in time bases for display scanning. It is used as the point for subtractive synthesis, as a sawtooth wave of constant period contains odd. Other waveforms are often called composite waveforms and can often be described as a combination of a number of waves or other basis functions added together. The Fourier series describes the decomposition of periodic waveforms, such that any periodic waveform can be formed by the sum of a set of fundamental, finite-energy non-periodic waveforms can be analyzed into sinusoids by the Fourier transform. AC waveform Arbitrary waveform generator Spectrum analyzer Waveform monitor Waveform viewer Wave packet Yuchuan Wei, common Waveform Analysis, A New And Practical Generalization of Fourier Analysis. Springer US, Aug 31,2000 Waveform Definition Hao He, Jian Li, Waveform design for active sensing systems, a computational approach. Solomon W. Golomb, and Guang Gong, Signal design for good correlation, for wireless communication, cryptography, and radar
14.
Electronic filter
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Electronic filters are circuits which perform signal processing functions, specifically to remove unwanted frequency components from the signal, to enhance wanted ones, or both. Electronic filters can be, passive or active analog or digital high-pass, low-pass, band-pass, band-stop, see the article on linear filters for details on their design and analysis. The oldest forms of filters are passive analog linear filters. These are known as RC and RL single-pole filters respectively, more complex multipole LC filters have also existed for many years, and their operation is well understood. Hybrid filters are possible, typically involving a combination of analog amplifiers with mechanical resonators or delay lines. Other devices such as CCD delay lines have also used as discrete-time filters. With the availability of digital processing, active digital filters have become common. Passive implementations of filters are based on combinations of resistors, inductors and capacitors. These types are known as passive filters, because they do not depend upon an external power supply and/or they do not contain active components such as transistors. Inductors block high-frequency signals and conduct low-frequency signals, while capacitors do the reverse, the inductors and capacitors are the reactive elements of the filter. The number of elements determines the order of the filter, in this context, an LC tuned circuit being used in a band-pass or band-stop filter is considered a single element even though it consists of two components. At high frequencies, sometimes the inductors consist of single loops or strips of metal. These inductive or capacitive pieces of metal are called stubs, the simplest passive filters, RC and RL filters, include only one reactive element, except hybrid LC filter which is characterized by inductance and capacitance integrated in one element. An L filter consists of two elements, one in series and one in parallel. Three-element filters can have a T or π topology and in either geometries, the components can be chosen symmetric or not, depending on the required frequency characteristics. The high-pass T filter in the illustration, has a low impedance at high frequencies. That means that it can be inserted in a line, resulting in the high frequencies being passed. Likewise, for the illustrated low-pass π filter, the circuit can be connected to a line, transmitting low frequencies
15.
Ring modulation
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Also a ring modulator as an effects unit is an application of it. It is referred to as ring modulation because the circuit of diodes originally used to implement this technique took the shape of a ring. This circuit is similar to a rectifier, except that instead of the diodes facing left or right. The carrier, which is AC, at a time, makes one pair of diodes conduct. The conducting pair carry the signal from the transformer secondary to the primary of the transformer at the right. If the left carrier terminal is positive, the top and bottom diodes conduct, if that terminal is negative, then the side diodes conduct, but create a polarity inversion between the transformers. This action is much like that of a DPDT switch wired for reversing connections, Ring modulators frequency mix or heterodyne two waveforms, and output the sum and difference of the frequencies present in each waveform. This process of ring modulation produces a signal rich in partials, as well, neither the carrier nor the incoming signal are prominent in the outputs, and ideally, not at all. When the oscillators frequencies are not harmonically related, ring modulation creates inharmonics, if the same signal is sent to both inputs of a ring modulator, the resultant harmonic spectrum is the original frequency domain doubled. Regarded as multiplication, this amounts to squaring. However, some distortion occurs due to the voltage drop of the diodes. Some modern ring modulators are implemented using digital signal processing techniques by simply multiplying the time domain signals, before digital music synthesizers became common, at least some analog synthesizers used analog multipliers for this purpose, they were closely related to those used in electronic analog computers. Multiplication in the domain is the same as convolution in the frequency domain, so the output waveform contains the sum. Thus, in the case where two sine waves of frequencies f1 and f2 are multiplied, two new sine waves are created, with one at f1 + f2 and the other at f2 - f1. The two new waves are unlikely to be related and the original signals are not present. It is this that gives the ring modulator its unique tones, intermodulation products can be generated by carefully selecting and changing the frequency of the two input waveforms. If the signals are processed digitally, the frequency-domain convolution becomes circular convolution, if the signals are wideband, this will cause aliasing distortion, so it is common to oversample the operation or low-pass filter the signals prior to ring modulation. The remaining difference frequencies have an inverted spectrum—High frequencies become low, on the C64 SID chip, ring modulation multiplies the triangle wave of oscillator 1 and oscillator 3
16.
Commodore 64
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The Commodore 64, also known as the C64, C-64, C=64, or occasionally CBM64 or VIC-64 in Sweden, is an 8-bit home computer introduced in January 1982 by Commodore International. It is listed in the Guinness World Records as the single computer model of all time. Volume production started in early 1982, marketing in August for US$595, preceded by the Commodore VIC-20 and Commodore PET, the C64 took its name from its 64 kilobytes of RAM. It had superior sound and graphical specifications compared to earlier systems such as the Apple II and Atari 800, with multi-color sprites. The C64 dominated the low-end computer market for most of the 1980s. Sam Tramiel, a later Atari president and the son of Commodores founder, said in a 1989 interview, When I was at Commodore we were building 400,000 C64s a month for a couple of years. In the UK market, the C64 faced competition from the BBC Micro and the ZX Spectrum, part of the Commodore 64s success was its sale in regular retail stores instead of only electronics and/or computer hobbyist specialty stores. Commodore produced many of its parts in-house to control costs, including custom integrated circuit chips from MOS Technology and it has been compared to the Ford Model T automobile for its role in bringing a new technology to middle-class households via creative and affordable mass-production. Approximately 10,000 commercial software titles have made for the Commodore 64 including development tools, office productivity applications. C64 emulators allow anyone with a computer, or a compatible video game console. The C64 is also credited with popularizing the computer demoscene and is used today by some computer hobbyists. In 2008,17 years after it was taken off the market, in January 1981, MOS Technology, Inc. Commodores integrated circuit design subsidiary, initiated a project to design the graphic, Design work for the chips, named MOS Technology VIC-II and MOS Technology SID, was completed in November 1981. Commodore then began a game console project that would use the new chips—called the Ultimax or the Commodore MAX Machine and this project was eventually cancelled after just a few machines were manufactured for the Japanese market. At the same time, Robert Bob Russell and Robert Bob Yannes were critical of the current product line-up at Commodore, with the support of Al Charpentier and Charles Winterble, they proposed to Commodore CEO Jack Tramiel a true low-cost sequel to the VIC-20. Tramiel dictated that the machine should have 64 KB of random-access memory, although 64-Kbit dynamic random-access memory chips cost over US$100 at the time, he knew that DRAM prices were falling, and would drop to an acceptable level before full production was reached. The product was named the VIC-40 as the successor to the popular VIC-20. The team that constructed it consisted of Yash Terakura, Bob Russell, Bob Yannes, the design, prototypes and some sample software were finished in time for the show, after the team had worked tirelessly over both Thanksgiving and Christmas weekends
17.
Commodore International
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Commodore International was a North American home computer and electronics manufacturer. Commodore International, along with its subsidiary Commodore Business Machines, participated in the development of the computer industry in the 1970s and 1980s. The company developed and marketed one of the worlds best-selling desktop computers, the company that would become Commodore Business Machines, Inc. was founded in 1954 in Toronto as the Commodore Portable Typewriter Company by Polish immigrant and Auschwitz survivor Jack Tramiel. He moved to Toronto to start production, by the late 1950s a wave of Japanese machines forced most North American typewriter companies to cease business, but Tramiel instead turned to adding machines. In 1955, the company was incorporated as Commodore Business Machines. In 1962, Commodore went public on the New York Stock Exchange, in the late 1960s, history repeated itself when Japanese firms started producing and exporting adding machines. The companys main investor and chairman, Irving Gould, suggested that Tramiel travel to Japan to understand how to compete, instead, he returned with the new idea to produce electronic calculators, which were just coming on the market. Commodore soon had a profitable calculator line and was one of the popular brands in the early 1970s. However, in 1975, Texas Instruments, the supplier of calculator parts, entered the market directly. Commodore obtained an infusion of cash from Gould, which Tramiel used beginning in 1976 to purchase several second-source chip suppliers, including MOS Technology, Inc. in order to assure his supply. He agreed to buy MOS, which was having troubles of its own, through the 1970s, Commodore also produced numerous peripherals and consumer electronic products such as the Chessmate, a chess computer based around a MOS6504 chip, released in 1978. In December 2007 when Tramiel was visiting the Computer History Museum in Mountain View, California, for the 25th anniversary of the Commodore 64 and he said, I wanted to call my company General, but theres so many Generals in the U. S. Then I went to Admiral, but that was taken, so I wind up in Berlin, Germany, with my wife, and we were in a cab, and the cab made a short stop, and in front of us was an Opel Commodore. Tramiel gave this account in interviews, but Opels Commodore didnt debut until 1967. Once Chuck Peddle had taken over engineering at Commodore, he convinced Jack Tramiel that calculators were already a dead end, from PETs 1977 debut, Commodore would be a computer company. The operational headquarters, where research and development of new products occurred, retained the name Commodore Business Machines, in 1980 Commodore launched production for the European market in Braunschweig. By 1980 Commodore was one of the three largest microcomputer companies, and the largest in the Common Market and this was addressed with the introduction of the VIC-20 in 1981, which was introduced at a cost of US$299 and sold in retail stores. Commodore took out ads featuring William Shatner asking consumers Why buy just a video game
18.
Consumer Electronics Show
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The Consumer Electronics Show is an annual trade show organized by the Consumer Technology Association. Held in January at the Las Vegas Convention Center in Las Vegas, Nevada, United States, the first CES was held in June 1967 in New York City. It was a spinoff from the Chicago Music Show, which then had served as the main event for exhibiting consumer electronics. The event had 17,500 attendees and over 100 exhibitors, from 1978 to 1994, CES was held twice each year, once in January in Las Vegas known as Winter Consumer Electronics Show and once in June in Chicago, known as Summer Consumer Electronics Show. The winter show was held in Las Vegas in 1995 as planned. However, the inaugural E3 gaming show was scheduled to be held on the West Coast in May and proved a source of increasing competition, causing the Philadelphia Summer CES show to be cancelled. The 1996 Winter show was held in Las Vegas in January, followed by a Summer show this time in Orlando, Florida. Again, the 1997 Winter show in Las Vegas was very successful, the next Summer show was scheduled to be held in conjunction with Spring COMDEX in Atlanta, however when only two dozen-or-so exhibitors signed on, the CES portion of the show was cancelled. In 1998, the changed to a once-a-year format with Las Vegas as the location. In Las Vegas, the show is one of the largest, taking up to 18 days to set up, run, organizers held the first CES in New York City from June 24 to 28,1967. The 200 exhibitors attracted 17,500 attendees to the Hilton, on view, the latest pocket radios and TVs sporting integrated circuits. In a one-time experiment, the Summer CES1993 was open to the general public, major announcements during this edition were, Capcom unveils Mega Man X First Time in North American. The Blu-ray Group held at the January 2004 CES the first US press conference to promote the Blu-ray Disc format, the 2005 CES was from January 6–9,2005, in Las Vegas, Nevada at the Las Vegas Convention Center. Samsung showed off a 102-inch plasma television, zimiti Ltd won the Best of Innovators award for Personal Electronics. It is the only British company to have won this award, the 2006 exhibition took place on January 5–8,2006 at the Las Vegas Convention Center, the Sands Convention Center, the Alexis Park Hotel and the Las Vegas Hilton Hotel. HDTV was a theme in the Bill Gates keynote as well as many of the other manufacturers speeches. The standards competition between HD DVD and Blu-ray Disc was conspicuous, with some of the first HD movie releases, philips showed a rollable display prototype whose screen can retain an image for several months without electricity. Hillcrest Labs won the Best Of Innovations award in the video category for software and hardware that allows a television to be controlled with natural gestures
19.
Las Vegas Valley
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The Las Vegas Valley is a major metropolitan area located in the southern part of the U. S. state of Nevada. The largest urban agglomeration in the state, it is the heart of the Las Vegas–Paradise-Henderson, the Valley is largely defined by the Las Vegas Valley landform, a 600 sq mi basin area surrounded by mountains to the north, south, east and west of the metropolitan area. The Valley is home to the three largest incorporated cities in Nevada, Las Vegas, Henderson and North Las Vegas, six unincorporated towns governed by the Clark County government are part of the Las Vegas Township and constitute the largest community in the state of Nevada. Since the 1990s the Las Vegas Valley has seen exponential growth, in 2014, a record breaking 41 million visited the Las Vegas area, producing a gross metropolitan product of more than $100 billion. The first reported non-Native American visitor to the Las Vegas Valley was the Mexican scout Rafael Rivera in 1829. Las Vegas was named by Mexicans in the Antonio Armijo party, including Rivera, in the 19th century, areas of the valley contained artesian wells that supported extensive green areas, or meadows, hence the name Las Vegas. The area was settled by Mormon farmers in 1854 and later became the site of a United States Army fort in 1864. Since the 1930s, Las Vegas has generally been identified as a center as well as a resort destination. Nellis Air Force Base is located in the northeast corner of the valley, the ranges that the Nellis pilots use and various other land areas used by various federal agencies, limit growth of the valley in terms of geographic area. Businessman Howard Hughes arrived in the late 1960s and purchased many casino hotels, as well as television, legitimate corporations began to purchase casino hotels as well, and the mob was run out by the federal government over the next several years. The constant stream of tourist dollars from the hotels and casinos was augmented by a new source of money from the establishment of what is now Nellis Air Force Base. The influx of personnel and casino job-hunters helped start a land building boom which is now leveling off. The Las Vegas area remains one of the top entertainment destinations. The valley is contained in the Las Vegas Valley landform and this includes the cities of Las Vegas, North Las Vegas, and Henderson, and the unincorporated towns of Paradise, Spring Valley, Sunrise Manor, Enterprise, Winchester, and Whitney. The valley is located within the larger metropolitan area, as the metropolitan area covers all of Clark County -including parts that do not fall within the valley. The government of Clark County has an Urban Planning Area of Las Vegas and this definition is a roughly rectangular area, about 20 mi from east to west and 30 miles from north to south. Notable exclusions from the Urban Planning Area include Red Rock, Blue Diamond, the Las Vegas Metropolitan Police Department is the largest police department in the valley and the state and exercises jurisdiction in the entire county. The department does not exercise jurisdiction in areas with separate police forces such as North Las Vegas, Henderson, Boulder City, Nellis Air Force Base
20.
Random-access memory
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Random-access memory is a form of computer data storage which stores frequently used program instructions to increase the general speed of a system. A random-access memory device allows data items to be read or written in almost the same amount of time irrespective of the location of data inside the memory. RAM contains multiplexing and demultiplexing circuitry, to connect the lines to the addressed storage for reading or writing the entry. Usually more than one bit of storage is accessed by the same address, in todays technology, random-access memory takes the form of integrated circuits. RAM is normally associated with types of memory, where stored information is lost if power is removed. Other types of non-volatile memories exist that allow access for read operations. These include most types of ROM and a type of memory called NOR-Flash. Integrated-circuit RAM chips came into the market in the early 1970s, with the first commercially available DRAM chip, early computers used relays, mechanical counters or delay lines for main memory functions. Ultrasonic delay lines could only reproduce data in the order it was written, drum memory could be expanded at relatively low cost but efficient retrieval of memory items required knowledge of the physical layout of the drum to optimize speed. Latches built out of vacuum tube triodes, and later, out of transistors, were used for smaller and faster memories such as registers. Such registers were relatively large and too costly to use for large amounts of data, the first practical form of random-access memory was the Williams tube starting in 1947. It stored data as electrically charged spots on the face of a cathode ray tube, since the electron beam of the CRT could read and write the spots on the tube in any order, memory was random access. The capacity of the Williams tube was a few hundred to around a thousand bits, but it was smaller, faster. In fact, rather than the Williams tube memory being designed for the SSEM, magnetic-core memory was invented in 1947 and developed up until the mid-1970s. It became a form of random-access memory, relying on an array of magnetized rings. By changing the sense of each rings magnetization, data could be stored with one bit stored per ring, since every ring had a combination of address wires to select and read or write it, access to any memory location in any sequence was possible. Magnetic core memory was the form of memory system until displaced by solid-state memory in integrated circuits. Data was stored in the capacitance of each transistor, and had to be periodically refreshed every few milliseconds before the charge could leak away
21.
Computer keyboard
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In computing, a computer keyboard is a typewriter-style device which uses an arrangement of buttons or keys to act as a mechanical lever or electronic switch. Following the decline of punch cards and paper tape, interaction via teleprinter-style keyboards became the input device for computers. A keyboard typically has characters engraved or printed on the keys, however, to produce some symbols requires pressing and holding several keys simultaneously or in sequence. While most keyboard keys produce letters, numbers or signs, other keys or simultaneous key presses can produce actions or execute computer commands. In normal usage, the keyboard is used as a text entry interface to type text and numbers into a word processor, in a modern computer, the interpretation of key presses is generally left to the software. A computer keyboard distinguishes each physical key from every other and reports all key presses to the controlling software, Keyboards are also used for computer gaming, either with regular keyboards or by using keyboards with special gaming features, which can expedite frequently used keystroke combinations. A keyboard is used to give commands to the operating system of a computer, such as Windows Control-Alt-Delete combination. A command-line interface is a type of user interface operated entirely through a keyboard and it was through such devices that modern computer keyboards inherited their layouts. Earlier models were developed separately by individuals such as Royal Earl House, earlier, Herman Hollerith developed the first keypunch devices, which soon evolved to include keys for text and number entry akin to normal typewriters by the 1930s. From the 1940s until the late 1960s, typewriters were the means of data entry. The keyboard remained the primary, most integrated computer peripheral well into the era of personal computing until the introduction of the mouse as a device in 1984. By this time, text-only user interfaces with sparse graphics gave way to comparatively graphics-rich icons on screen, One factor determining the size of a keyboard is the presence of duplicate keys, such as a separate numeric keyboard, for convenience. A keyboard with few keys is called a keypad, another factor determining the size of a keyboard is the size and spacing of the keys. Reduction is limited by the consideration that the keys must be large enough to be easily pressed by fingers. Alternatively a tool is used for pressing small keys, standard alphanumeric keyboards have keys that are on three-quarter inch centers, and have a key travel of at least 0.150 inches. Desktop computer keyboards, such as the 101-key US traditional keyboards or the 104-key Windows keyboards, include characters, punctuation symbols, numbers. The internationally common 102/104 key keyboards have a left shift key. Also the enter key is usually shaped differently, computer keyboards are similar to electric-typewriter keyboards but contain additional keys, such as the command or Windows keys
22.
Bil Herd
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Bil Herd is a computer engineer who created several designs for 8-bit home computers while working for Commodore Business Machines in the early to mid-1980s. Prior to the C128, Herd had done the initial architecture of the Commodore LCD computer, after leaving Commodore, Herd continued to design faster and more powerful computers with emphasis on machine vision and is a co-author on a patent involving n-dimensional pattern matching. Herd also designed an ultrasonic backup sensor for vehicles while working for Indian Valley Mfg. in 1986, Herd has undertaken an entrepreneurial role and is owner of several small companies. As for recent low-level computer hacking, he did an appearance by contributing a snippet of sprite logic code to the C64 DTV product designed by Jeri Ellsworth. Bil Herd currently produces videos for Hackaday and appeared in and narrated the documentary Growing the 8 Bit Generation about the days of home computers. Voluntary health care work, 1989–1996, Fellowship First Aid Squad / Mount Laurel EMS Inc, highest rank, Captain 1991–1995, Cooper Trauma Center - Camden, NJ, Trauma Technician Bagnall, Brian, On The Edge, The Spectacular Rise and Fall of Commodore, ISBN 0-9738649-0-7
23.
Commodore Plus/4
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The Commodore Plus/4 is a home computer released by Commodore International in 1984. The Plus/4 name refers to the four-application ROM resident office suite, internally, the Plus/4 shares the same basic architecture as the lower-end Commodore 16 and 116 models, and is able to use software and peripherals designed for them. However, it is not compatible with the well-established Commodore 64, while the Plus/4 had some success in Europe, it was a failure in the United States, where it was derided as the Minus/60. In the early 1980s, Commodore found itself engaged in a war in the home computer market. Companies like Texas Instruments and Timex Corporation were releasing computers that undercut the price of Commodores PET line, Commodores MOS Technology division had designed a video chip but could not find any third-party buyers. The VIC-20 resulted from the confluence of events and it was introduced in 1980 at a list price of $299.95. Later, spurred by the competition, Commodore was able to reduce the VICs street price to $99, still, the C64 went on to become a best-seller and was selling for $199 at the time of the Plus/4s introduction. The companys third salvo – which, as it turned out, was fired just as most of Commodores competition was leaving the computer market – was the C116, C16, and 264. There were also prototypes of a 232, basically a 32 KB version of the Plus/4 without the software ROMs, the latter two models never made it to production. All these computers used a 6502 compatible MOS8501 that was clocked approximately 75% faster than the CPUs used in the VIC-20 and C64, and a MOS Technology TED all-in-one video, sound, and I/O chip. The Plus/4s design is thus closer to that of the VIC-20 than that of the C64. The Plus/4 was the computer of the line. The Plus/4 had 64 KB of memory while the C16 and 116 had 16 KB, the Plus/4 had built-in software, whereas the others did not. The Plus/4 and C16 had full-travel keyboards, the 116 used a rubber chiclet keyboard that was superior to the flat membrane keyboards used on less-expensive Timex-Sinclair computers. The C116 was only sold in Europe, all of the machines were distinguished by their dark gray cases and light gray keys. This was a reversal of the scheme on the 64 and VIC. The Plus/4 was introduced in June 1984 and priced at US$299, Commodores intent with the Plus/4 was not to replace the C64, but to expand the home computer market and sell the Plus/4 to users who were more interested in serious applications than in gaming. By 1984, however, most of these customers were beginning to switch to the new, low-cost IBM PC compatibles such as the Leading Edge Model D and Tandy 1000 series
24.
Dave Haynie
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Dave Haynie is the former Commodore International chief engineer on high end and advanced projects. He is still quite vocal in the Amiga community, Dave was born David Bruce Haynie on May 23,1961, in Summit, New Jersey, United States. He moved to Colts Neck, New Jersey, in 1966, a few early Heathkit projects, and, at the age of 12, a run-in with his dads borrowed HP desktop calculator changed his life forever. From 12 years on, he taught himself programming, initially on timeshare systems from his dads account at Bell Laboratories, later on, he wrote programs on his best friend Scott Scherers Commodore PET2001, the first home computer he had seen up close. He left for college at Carnegie Mellon University in 1979, four years later, he graduated with a double BS in Electrical Engineering and Mathematics. He started work at Commodore in 1983 as an engineer under Bil Herd and his first project was to help complete the TED systems comprising Plus/4, C16 and more. After completing the Commodore 128 Bil Herd left the company and Dave Haynie was promoted to engineer in the low-end group. After Commodore acquired Amiga, Dave Haynie ended up primary engineer on the expandable A2000 computer, later, he joined Bob Welland on the A2620 CPU module, and launched the follow-up A2630 the year thereafter. These were delivered in the A2500/20 and A2500/30, in 1989 he started designing the Zorro III expansion bus architecture, and in 1990, with Greg Berlin, Hedley Davis, Jeff Boyer, and Scott Hood, created the Amiga 3000. He also worked on a system for the Advanced Amiga Architecture chipset and he defined a new system architecture for this, the Acutiator project. Most of this work, as most of the work at Commodore, was terminated by the end of 1993 due to financial problems within Commodore. Dave Haynie left Commodore in June 1994, over a month after the bankruptcy, for Scala and he made a two-hour film of the last days of Commodore, from the West Chester Engineers perspective, released in 1994, called The Deathbed Vigil and other tales of digital angst. Driven in part by the experiences of his friends at Amiga, he joined Scala, the goal here was to advance some desktop presentation technology for use on other platforms. Daves ability to switch-hit hardware and software was useful, Scala planned a hardware project and he designed Scalas Class Definition Language and compiler, some high level tools for the operating system Scala was defining for portable multimedia. But the hardware projects never came around, in 1995, Haynie did some consulting, along with Andy Finkel, for Amiga Technologies, the company resulting from Escoms acquisition of the Commodore assets. He and Finkel defined a next generation Amiga platform, based on a $500 PowerPC platform, however, ESCOMs own financial problems killed this before it went very far. The Amiga Technologies experience, however, wasnt for naught, some of the managers liked what they saw in Haynie and Finkel. In June 1996 he joined managers Stefan Domeyer and Geerd Ebeling a German startup company initially called PIOS Computer, later renamed to Metabox, Metabox was initially selling Apple Macintosh clones and attempting to sell Amiga follow-on systems based on the PowerPC processor
25.
Alt key
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For a list of keyboard shortcuts, see Table of keyboard shortcuts ⌥ Opt or Alt The Alt key on a computer keyboard is used to change the function of other pressed keys. Thus, the Alt key is a key, used in a similar fashion to the Shift key. For example, simply pressing A will type the letter a, but if you hold down either Alt key while pressing A, the computer will perform an Alt+A function, the international standard ISO/IEC 9995-2 calls it Alternate key. The key is located on side of the Space bar. Both placements are in accordance with ISO/IEC 9995-2, the standardized keyboard symbol for the Alt key is given in ISO/IEC 9995-7 as symbol 25, and in ISO7000 “Graphical symbols for use on equipment” as symbol ISO-7000-2105. This symbol is encoded in Unicode as U+2387 alternative key symbol, the Alt key should not be confused with the Altmode key on some Teletype and ASCII terminals, which is a synonym for the ASCII escape character. The Alt key has come to replace the Meta key of the old MIT keyboards, in their original function, both Alt and Meta would set the high bit of the signal generated by the key to 1. However, in software, due to the requirement of the high bit for internationalization. Since the 1990s Alt has been printed on the Option key on most Mac keyboards, Alt is used in non-Mac software, such as non-macOS Unix and Windows programs, but in macOS it is always referred as the Option key. The Option keys behaviour in macOS differs slightly from that of the Windows Alt key, the Alt key is well known as part of the key combinations, Ctrl+Alt+Delete brings up a task manager in some operating systems, see Control-Alt-Delete. Alt+⌘ Cmd+Esc brings up the Force Quit window in Apple’s macOS, ctrl+Alt+← Backspace usually causes the X display server to shut down or to restart, see Control-Alt-Backspace. Alt+F4 closes the current window on most windowing systems, alt+Tab ↹ switches between the currently opened windows on most windowing systems, see Alt-Tab. Alt+↵ Enter allows for a new line when Enter does another command, in Microsoft Windows, holding down the Alt key while typing in numbers on the numeric keypad allows the user to type special characters not normally available on the keyboard. For example, holding down Alt while typing 0225 on the numeric keypad will result in á and these extended keyboard characters are useful for persons using foreign languages, mathematics, currency symbols, business use, etc. Some computers work the same if the Num Lock key is on, on a Macintosh, the Alt key is called the Option key. It is not used to enter numeric character codes, instead, keyboard letters and numbers are used. The diagram below shows the characters a US Mac keyboard will produce when the Option key is pressed. The highlighted orange keys show the accents available from the combination of the Alt key, the accent then can be applied to associated letters both lower and uppercase
26.
Esc key
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On computer keyboards, the Esc key is a key used to generate the escape character. It is now placed at the top left corner of the keyboard. The keyboard symbol for the ESC key is standardized in ISO/IEC 9995-7 as symbol 29 and this symbol is encoded in Unicode as U+238B broken circle with northwest arrow. The Escape keys creation is credited to Bob Bemer, a programmer who worked for IBM. He created the key in 1960 to allow programmers working with machines to switch from one type of code to another. Much later printers and computer terminals that would use escape sequences often would take more than one following byte as part of a special sequence and this key combination still works as of Windows 10. Microsoft Windows makes use of Esc for many key shortcuts, many of these shortcuts have been present since Windows 3.0, through Windows XP, Windows Vista, Windows 7, Windows 8, and Windows 10. In OS X, Esc usually closes or cancels a dialog box or sheet, the ⌘ Command+⌥ Option+⎋ Esc combination opens the Force Quit dialog box, allowing users to end non-responsive programs. Another use for the Esc key, in combination with the Command key, is switching to Front Row, if installed. In most computer games, the key is used as a pause button and/or as a way to bring up the in-game menu. In the vi family of text editors, escape is used to switch modes and this usage is due to escape being conveniently placed in what is now the tab position on the ADM-3A terminal keyboard used to develop vi, though it is now inconveniently placed. Although such devices are long out of use, standard processing of ANSI Escape sequences very similar to 1970s VT100, is implemented in both ANSI
27.
Tab key
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Tab ↹ Tab key on a keyboard is used to advance the cursor to the next tab stop. The word tab derives from the word tabulate, which means to arrange data in a tabular, or table, when a person wanted to type a table on a typewriter, there was a lot of time-consuming and repetitive use of the space bar and backspace key. To simplify this, a bar was placed in the mechanism with a moveable lever stop for every position across the page. Initially these were set by hand, but later tab set, when the tab key was depressed, the carriage advanced to the next tab stop. These were set to correspond to the particular locations of the table, hence tab. In word processing and text editing the Tab key will move the insertion point to the next tab stop in a table. When filling out a form, pressing Tab will move the cursor to the next field. In many graphical applications, especially on Windows, the Tab key will move the focus to every control or widget such as buttons so that the interface can be used without a mouse at all. On OS X, this is an option called Full Keyboard Access, Tab may be used to complete a partially typed piece of text. For example, in some command-line interfaces, you may type the first few characters of a command or file-name, if there is no ambiguity about your intent, the rest of the characters will appear automatically. This usage is common on Unix than Windows. In PC video games, the Tab key is often used to show scores in multiplayer games. For single player games it is used to show the world map or the players inventory. The most known and common tab is a tab, which in ASCII has the decimal character code of 9. In C and many other programming languages the escape code \t can be used to put this character into a string constant, the horizontal tab is usually generated by the Tab key on a standard keyboard. A vertical tab also exists and has ASCII decimal character code 11, in EBCDIC the code for HT is 5, and VT is 11. Originally, printer mechanisms used mechanical tab stops to indicate where the tabs went. This was done horizontally with movable metal prongs in a row, initially these were manually set up to match the preprinted forms that were loaded into the printer
28.
Numeric keypad
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A numeric keypad, number pad, numpad, or ten key, is the palm-sized, 17-key section of a standard computer keyboard, usually on the far right. It provides calculator-style efficiency for entering numbers, the numpads keys are digits 0 to 9, +, -, * and / symbols. Num Lock, and ↵ Enter keys, laptop keyboards often do not have a numpad, but may provide numpad input by holding a modifier key and operating keys on the standard keyboard. Particularly large laptops may have space for a real numpad, numeric keypads usually operate in two modes. When Num Lock is off, keys 8,6,2, and 4 act like arrow/navigation keys up, right, down, and left, and 7,9,3, and 1 act like Home, PgUp, PgDn, and End, respectively. When Num Lock is on, digit keys produce the corresponding digit, on Apple Macintosh computers, which lack a Num Lock key, the numeric keypad always produces only numbers, the Num Lock key is replaced by the Clear key. The arrangement of digits on numeric keypads with the 7-8-9 keys two rows above the 1-2-3 keys is derived from calculators and cash registers and it is notably different from the layout of telephone Touch-Tone keypads which have the 1-2-3 keys on top and 7-8-9 keys on the third row. Numeric keypads are useful for entering long sequences of numbers quickly, for example in spreadsheets, financial/accounting programs, Input in this style is similar to a calculator or adding machine. A numpad is also useful on Windows PCs for typing alt codes for special symbols, for example the symbol, °. Ten key speed is measured in Keystrokes per Hour, the minimum required speed for many data entry jobs is around 9000 KPH with good accuracy. A speed of 12,000 is considered excellent, the numeric keypad is used by some systems for input of Chinese characters, for example CKC Chinese Input System and Q9 input method. Numeric keypads are used for playing some computer games where the player must control a character. Unlike arrow keys, the numeric keypad allows diagonal movement, for keyboards without a numeric keypad, some games provide alternative movement keys, such as classic Rogues HJKL keys. The numeric keypad can also be an alternative to the WASD keys for navigation in computer gaming and this can be an attractive option for left-handed people who prefer to use the mouse with their left hand
29.
Productivity software
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Its names arose from the fact that it increases productivity, especially of individual office workers, from typists to knowledge workers, although its scope is now wider than that. Office suites, which word processing, spreadsheet, and relational database programs to the desktop in the 1980s, are the core example of productivity software. Some 78% of middle-skill occupations now require the use of productivity software, in the 2010s, productivity software has become even more consumerized than it already was, as computing becomes ever more integrated into daily personal life. Productivity software traditionally run directly on a computer, for example, Commodore Plus/4 model of computer contained in ROM four applications of productivity software. Productivity software is one of the people use personal computers. Productivity software help the professional or common user to enhance and complete their tasks, an office suite is a collection of bundled productivity software intended to be used by knowledge workers. The components are generally distributed together, have a consistent user interface and usually can interact with each other, the earliest office suite for personal computers was Starburst in the early 1980s, comprising the word processor WordStar, together with companion apps CalcStar and DataStar. Various other suites arose in the 1980s, and over the course of the 1990s Microsoft Office came to dominate the market, existing office suites contain wide range of various components
30.
Machine code
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Machine code or machine language is a set of instructions executed directly by a computers central processing unit. Each instruction performs a specific task, such as a load. Every program directly executed by a CPU is made up of a series of such instructions, numerical machine code may be regarded as the lowest-level representation of a compiled or assembled computer program or as a primitive and hardware-dependent programming language. While it is possible to write directly in numerical machine code, it is tedious and error prone to manage individual bits and calculate numerical addresses. For this reason machine code is almost never used to programs in modern contexts. Almost all practical programs today are written in languages or assembly language. However, the interpreter itself, which may be seen as an executor or processor, performing the instructions of the source code, every processor or processor family has its own machine code instruction set. Instructions are patterns of bits that by physical design correspond to different commands to the machine, thus, the instruction set is specific to a class of processors using the same architecture. Successor or derivative processor designs often include all the instructions of a predecessor, systems may also differ in other details, such as memory arrangement, operating systems, or peripheral devices. Because a program normally relies on such factors, different systems will not run the same machine code. A machine code instruction set may have all instructions of the same length, how the patterns are organized varies strongly with the particular architecture and often also with the type of instruction. Not all machines or individual instructions have explicit operands, an accumulator machine has a combined left operand and result in an implicit accumulator for most arithmetic instructions. Other architectures have accumulator versions of common instructions, with the accumulator regarded as one of the general registers by longer instructions, a stack machine has most or all of its operands on an implicit stack. Special purpose instructions also often lack explicit operands and this distinction between explicit and implicit operands is important in machine code generators, especially in the register allocation and live range tracking parts. A good code optimizer can track implicit as well as explicit operands which may allow more frequent constant propagation, constant folding of registers, a computer program is a sequence of instructions that are executed by a CPU. While simple processors execute instructions one after another, superscalar processors are capable of executing several instructions at once, program flow may be influenced by special jump instructions that transfer execution to an instruction other than the numerically following one. Conditional jumps are taken or not depending on some condition, a much more readable rendition of machine language, called assembly language, uses mnemonic codes to refer to machine code instructions, rather than using the instructions numeric values directly. For example, on the Zilog Z80 processor, the machine code 00000101, the MIPS instruction set provides a specific example for a machine code whose instructions are always 32 bits long
31.
Type-in program
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Type-ins were often seen as useful for learning programming, allowing users to begin their programming efforts by porting a program written for one system for use on another. Here is an example of a type-in, Listing 1. 20 GOTO10 To use this type-in, a reader would take a copy of the program listing, such as from a magazine or book, sit down at a computer. Computers of this era automatically booted into a programming environment – even the commands to load, after typing the program in, the user would be able to run it and also to save it to disk or cassette for future use. Users were often cautioned to save the program before running it, as errors could result in a crash requiring a reboot, the simple program displayed above is a trivial example - many type-ins were fully functional games or application software, sometimes rivaling commercial packages. Type-ins were usually written in BASIC or a combination of a BASIC loader, in some cases, a special program for entering machine language numerically was provided. Programs with a language component sometimes included assembly language listings for users who had assemblers. The downside of type-ins was labor, the work required to enter a medium-sized type-in was on the order of hours. If the resulting program turned out not to be to the users taste, additionally, type-ins were error-prone, both for users and for the magazines. This was especially true of the language parts of BASIC programs. While a BASIC program would stop with an error at an incorrect statement. This made the entry of programs difficult. To counter the difficulty of keying a type-in, the MIKBUG machine code monitor for the Motorola 6800 of the late 1970s incorporated a checksum into its program listings. Later, some magazines developed checksum programs of their own, there were many different styles of checksum program, usually depending on the type of program being entered and on the complexity of the checksummer. Checksummers were proprietary and were printed in every issue of the magazine. The most basic distinction was whether the checksummer was run only once, the former type either read the typed-in computer code off a disk, or read it directly from memory. The checksum program would print a checksum for each line of code, the magazine would print the correct checksums adjacent to the listing, and the user would compare the two to catch errors. More advanced checksum programs were used interactively and they would take a line of code as it was entered and immediately produce a checksum which could be compared to the printed listing
32.
IBM Personal Computer
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The IBM Personal Computer, commonly known as the IBM PC, is the original version and progenitor of the IBM PC compatible hardware platform. It is IBM model number 5150, and was introduced on August 12,1981 and it was created by a team of engineers and designers under the direction of Don Estridge of the IBM Entry Systems Division in Boca Raton, Florida. IBM compatible became an important criterion for sales growth, only the Apple Macintosh family kept significant market share without compatibility with the IBM personal computer, International Business Machines, one of the worlds largest companies, had a 62% share of the mainframe computer market in 1981. Its share of the computer market, however, had declined from 60% in 1970 to 32% in 1980. In 1979 BusinessWeek asked, Is IBM just another stodgy, mature company, by 1981 its stock price had declined by 22%. IBMs earnings for the first half the year grew by 5. 3%—one third of the inflation rate—while those of minicomputer maker Digital Equipment Corporation grew by more than 35%. B. M, No longer dominates the computer business. IBM wished to avoid the outcome with the new personal computer industry, dominated by the Commodore PET, Atari 8-bit family, Apple II, Tandy Corporations TRS-80. With $150 million in sales by 1979 and projected growth of more than 40% in the early 1980s. The Japanese project, codenamed Go, ended before the 1981 release of the American-designed IBM PC codenamed Chess, whether IBM had waited too long to enter an industry in which Apple and others were already successful was unclear. An observer stated that IBM bringing out a computer would be like teaching an elephant to tap dance. Successful microcomputer company Vector Graphics fiscal 1980 revenue was $12 million, the company only sold through its internal sales force, had no experience with resellers or retail stores, and did not introduce the first product designed to work with non-IBM equipment until 1980. Another observer claimed that IBM made decisions so slowly that, when tested, as with other large computer companies, its new products typically required about four to five years for development. IBM had to learn how to develop, mass-produce. The potential importance to microcomputers of a company so prestigious, that a saying in American companies stated No one ever got fired for buying IBM, was nonetheless clear. InfoWorld, which described itself as The Newsweekly for Microcomputer Users, stated that for my grandmother, is far and away the media star, not because of its features, but because it exists at all. When the number eight company in the Fortune 500 enters the field, the influence of a personal computer made by a company whose name has literally come to mean computer to most of the world is hard to contemplate. The editorial acknowledged that some factions in our industry have looked upon IBM as the enemy, desktop sized programmable calculators by Hewlett Packard had evolved into the HP9830 BASIC language computer by 1972. In 1972–1973 a team led by Dr. SCAMP emulated an IBM1130 minicomputer to run APL\1130, in 1973 APL was generally available only on mainframe computers, and most desktop sized microcomputers such as the Wang 2200 or HP9800 offered only BASIC
33.
MOS Technology 6510
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The MOS Technology 6510 is an 8-bit microprocessor designed by MOS Technology, Inc. and is a modified form of the very successful 6502. The primary change from the 6502 was the addition of an 8-bit general purpose I/O port, in addition, the address bus could be made tristate. The 6510 was only used in the Commodore 64 home computer. In 1985, MOS produced the 8500, an HMOS version of the 6510, other than the process change, it is virtually identical to the NMOS version of the 6510. The 8500 was originally designed for use in the modernised C64, however, in 1985, limited quantities of 8500s were found on older NMOS-based C64s. It finally made its debut in 1987, appearing in a motherboard using the new 85xx HMOS chipset. The 7501/8501 variant of the 6510 was introduced in 1984 and it was used in Commodores C16, C116 and Plus/4 home computers, where its I/O port controlled not only the Datasette but also the CBM Bus interface. The main difference between 7501 and 8501 CPUs is that they were manufactured with different technologies,7501 was manufactured with HMOS-1 and 8501 with HMOS-2, the NMI signal are not available for MOS7501 and MOS8501. The 2 MHz-capable 8502 variant was used in the Commodore 128, all these CPUs are opcode compatible. The Commodore 1551 disk drive used the 6510T, a version of the 6510 with eight I/O lines, the NMI and RDY signals are not available. Interrupts in 65xx processors MOS6510 datasheet MOS6510 datasheet MOS6510 datasheet Marat Fayzullins emulator page A web server using a MOS6510 computer aka C64 unmodified
34.
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
35.
Hertz
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The hertz is the unit of frequency in the International System of Units and is defined as one cycle per second. It is named for Heinrich Rudolf Hertz, the first person to provide proof of the existence of electromagnetic waves. Hertz are commonly expressed in SI multiples kilohertz, megahertz, gigahertz, kilo means thousand, mega meaning million, giga meaning billion and tera for trillion. Some of the units most common uses are in the description of waves and musical tones, particularly those used in radio-. It is also used to describe the speeds at which computers, the hertz is equivalent to cycles per second, i. e. 1/second or s −1. In English, hertz is also used as the plural form, as an SI unit, Hz can be prefixed, commonly used multiples are kHz, MHz, GHz and THz. One hertz simply means one cycle per second,100 Hz means one hundred cycles per second, and so on. The unit may be applied to any periodic event—for example, a clock might be said to tick at 1 Hz, the rate of aperiodic or stochastic events occur is expressed in reciprocal second or inverse second in general or, the specific case of radioactive decay, becquerels. Whereas 1 Hz is 1 cycle per second,1 Bq is 1 aperiodic radionuclide event per second, the conversion between a frequency f measured in hertz and an angular velocity ω measured in radians per second is ω =2 π f and f = ω2 π. This SI unit is named after Heinrich Hertz, as with every International System of Units unit named for a person, the first letter of its symbol is upper case. Note that degree Celsius conforms to this rule because the d is lowercase. — Based on The International System of Units, the hertz is named after the German physicist Heinrich Hertz, who made important scientific contributions to the study of electromagnetism. The name was established by the International Electrotechnical Commission in 1930, the term cycles per second was largely replaced by hertz by the 1970s. One hobby magazine, Electronics Illustrated, declared their intention to stick with the traditional kc. Mc. etc. units, sound is a traveling longitudinal wave which is an oscillation of pressure. Humans perceive frequency of waves as pitch. Each musical note corresponds to a frequency which can be measured in hertz. An infants ear is able to perceive frequencies ranging from 20 Hz to 20,000 Hz, the range of ultrasound, infrasound and other physical vibrations such as molecular and atomic vibrations extends from a few femtoHz into the terahertz range and beyond. Electromagnetic radiation is described by its frequency—the number of oscillations of the perpendicular electric and magnetic fields per second—expressed in hertz. Radio frequency radiation is measured in kilohertz, megahertz, or gigahertz
36.
Commodore REU
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Commodores RAM Expansion Unit range of external RAM add-ons for their Commodore 64/128 home computers was announced at the same time as the C128. The REUs came in three models, initially the 1700 and 1750, and later the 1764. By the time of the 1985 CES show in Chicago, the engineers were able to display a spinning globe of the earth as a demonstration of Direct Memory Access by the new REU units. The REU hardware was designed by Frank Palia and the dedicated Integrated Circuit was designed by Victor Andrade. Fred Bowen and Terry Ryan adapted the kernel and Basic to accommodate the REU natively, additionally, the C128s built-in BASIC7.0 had three statements, STASH, FETCH, and SWAP, for storing and retrieving data from the REU. Officially, only the 1700 and 1750 were supported on the C128, the 256 kB model, the 1764, was released for the C64 at the same time. There were only minor differences between the three models, the 1700 utilizes sixteen 4164 64kx1 DRAMs, the 1764 has eight 41256 256kx1 DRAMs, and the 1750 has sixteen 41256 DRAMs. Some dealers unbundled the 1764 and the supply in order to sell the power supply to C64 users. During the late 1980s, there was a shortage of DRAM caused by the Reagan Administration enacting anti-dumping restrictions on Japanese manufacturers, thus 1750s were rare, however it was comparatively easy to upgrade a 1700 or 1764 to 512 kB. Several firms did this commercially, either selling upgraded units or upgrading customer-supplied units, in the early 1990s, DIY modification schemes to increase the capacity of an REU to one megabyte or higher appeared on various online services. The 1700s circuit board was identical to that of the 1750, on the 1750 and 1764, this trace was cut. The 1700 and 1750 had a resistor at position R4 that, according to Commodore engineer Fred Bowen, compensated for subtle differences in the port on the C64. Bowen and other CBM engineers recommended against using a 1764 with a C128 unless the resistor was added, or a 1700/1750 with a C64 unless the resistor was removed. It was possible to check for the presence of a 1750 by reading memory address $DF00s bit 4, which was 1 on a 1750, and 0 on a 1700 or 1764. However, since this procedure would not distinguish between a 1700 and a 1764, many programmers wrote to the RAM itself to find out the amount of memory installed, very little software made use of the REUs. Additionally, many commercial programs simply overwrote the memory space occupied by the RAM disk software. GEOS as well as other programs even used the REU for quick memory transfers within the host machines main memory by storing a memory block into the REU and then fetching it back to another location. Due to its speed relative to Commodores floppy drives or even the commercially available hard drives
37.
Heat sink
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In computers, heat sinks are used to cool central processing units or graphics processors. A heat sink is designed to maximize its surface area in contact with the medium surrounding it. Air velocity, choice of material, protrusion design and surface treatment are factors that affect the performance of a heat sink, heat sink attachment methods and thermal interface materials also affect the die temperature of the integrated circuit. Thermal adhesive or thermal grease improve the heat sinks performance by filling air gaps between the sink and the heat spreader on the device. A heat sink is made out of copper and/or aluminium. Copper is used because it has many desirable properties for thermally efficient, first and foremost, copper is an excellent conductor of heat. This means that high thermal conductivity allows heat to pass through it quickly. Aluminum is used in applications where weight is a big concern, a heat sink transfers thermal energy from a higher temperature device to a lower temperature fluid medium. The fluid medium is air, but can also be water. If the fluid medium is water, the sink is frequently called a cold plate. In thermodynamics a heat sink is a reservoir that can absorb an arbitrary amount of heat without significantly changing temperature. Practical heat sinks for electronic devices must have a higher than the surroundings to transfer heat by convection, radiation. The power supplies of electronics are not 100% efficient, so heat is produced that may be detrimental to the function of the device. As such, a sink is included in the design to disperse heat to improve efficient energy use. To understand the principle of a sink, consider Fouriers law of heat conduction. The rate at which heat is transferred by conduction, q k, is proportional to the product of the temperature gradient, Q k = − k A d T d x Consider a heat sink in a duct, where air flows through the duct. It is assumed that the heat sink base is higher in temperature than the air, when compact heat exchangers are calculated, the logarithmic mean air temperature is used. M ˙ is the air flow rate in kg/s
38.
Mode (computer interface)
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An interface that uses no modes is known as a modeless interface. Modeless interfaces avoid mode errors by making it impossible for the user to commit them, in Raskins sense and according to his definition, an interface is not modal as long as the user is fully aware of its current state. Raskin refers to this as locus of attention, if the users locus of attention changes to a different area, the state of the interface may then represent a mode since the user is no longer aware of it. Vi – has one mode for inserting text, and a mode for entering commands. There is also an ex mode for issuing more complex commands, under normal circumstances, the editor automatically returns to the previous mode after a command has been issued, however, it is possible to permanently move into this mode using Shift-Q. Emacs – has the concept of keys, which trigger a modal state by pressing the control key plus a letter key. Emacs then waits for additional keypresses that complete a keybinding and this differs from vi in that the mode always ends as soon as the command is called. Emacs also has major and minor modes that change the available commands. Modes are written in Emacs Lisp, and all modes may not be included with all versions, cisco IOS – certain commands are executed in a command mode. Tools chosen from a palette in photo-editing and drawing applications are examples of a modal interface, some advanced image editors have a feature where the same tools can be accessed nonmodally by a keypress, and remain active as long as the key is held down. Releasing the key returns the interface to the modal tool activated by the palette, video games can use game modes as a mechanic to enhance gameplay. Modal windows block all workflow in the program until the modal window is closed. A mode error can be startling and disorienting as the user copes with the sudden violation of his or her user expectations. Problems occur if a change in the system state happens unnoticed, another typical problem is a sudden change of state that interrupts a users activity, such as focus stealing. In such a situation it can happen that the user does some operations with the old state in mind. A very frustrating type of modality is created by a mode where the user does not find a way out, in other words, the most common source of mode errors may be the Caps Lock key. Other common modes available in PC keyboards are Insert and the other keys, Num lock. Dead keys for diacritics also create a mode, at least if they dont provide visual feedback that the next typed character will be modified
39.
Text mode
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Text mode is a computer display mode in which content is internally represented on a computer screen in terms of characters rather than individual pixels. Typically, the screen consists of a rectangular grid of character cells. Text mode is contrasted to all points addressable mode or other kinds of computer graphics modes, text mode applications communicate with the user with command-line interfaces and text user interfaces. A typical example is the IBM code page 437 character set and this was an analogy of early mechanical printers which had fixed pitch. This way, the output seen on the screen could be sent directly to the printer maintaining exactly the same format, depending on the environment, the screen buffer can be directly addressable. Programs that display output on remote video terminals must issue special control sequences to manipulate the screen buffer, the most popular standards for such control sequences are ANSI and VT100. Text mode video rendering came to prominence in the early 1970s, the advantages of text modes as compared to graphics modes include lower memory consumption and faster screen manipulation. Early framebuffers were standalone devices which cost thousands of dollars, in addition to the expense of the advanced high-resolution displays to which they were connected. For applications that required simple line graphics but for which the expense of a framebuffer could not be justified, but there were many computer applications for which all that was required was the ability to render ordinary text in a quick and cost-effective fashion to a cathode ray tube. Text mode avoids the problem of memory by having dedicated display hardware re-render each line of text from characters into pixels with each scan of the screen by the cathode ray. In turn, the hardware needs only enough memory to store the pixels equivalent to one line of text at a time. For example, a screen buffer sufficient to hold a standard grid of 80 by 25 characters requires at least 2,000 bytes. S. dollars, another advantage of text mode is that it has relatively low bandwidth requirements in remote terminal use. Text mode rendering with user-defined characters has also been useful for 2D computer, a video controller implementing a text mode usually uses two distinct areas of memory. Character memory or a table contains a raster font in use. Display matrix tracks which character is in each cell, in the simple case the display matrix can be just a matrix of code points, but it usually stores for each character position not only a code, but also attributes. The video controller has two registers, scan line counter and dot counter, serving as coordinates in the dot matrix. Each of them must be divided by corresponding glyph size to obtain an index in the display matrix, the character memory resides in a read-only memory in some systems. Other systems allow the use of RAM for this purpose, making it possible to redefine the typeface, in some historical graphics chips, including the TMS9918, the MOS Technology VIC, and the Game Boy graphics hardware, this was actually the canonical way of doing pixel graphics
40.
IBM PC compatible
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IBM PC compatible computers are those similar to the original IBM PC, XT, and AT, able to run the same software and support the same expansion cards as those. Such computers used to be referred to as PC clones, or IBM clones, Columbia Data Products built the first clone of the IBM personal computer by a clean room implementation of its BIOS. Early IBM PC compatibles used the computer bus as the original PC. The IBM AT compatible bus was named the Industry Standard Architecture bus by manufacturers of compatible computers. The term IBM PC compatible is now a historical description only, only the Apple Macintosh classic Mac OS and macOS kept significant market share without compatibility with the IBM personal computer, so consumers are typically identified as being a PC or Mac user. IBM decided in 1980 to market a low-cost single-user computer as quickly as possible in response to Apple Computers success in the microcomputer market. On 12 August 1981, the first IBM PC went on sale, there were three operating systems available for it. The least expensive and most popular was PC DOS made by Microsoft, in a crucial concession, IBMs agreement allowed Microsoft to sell its own version, MS-DOS, for non-IBM computers. The only component of the original PC architecture exclusive to IBM was the BIOS and this software would run on any machine using MS-DOS or PC-DOS. Software that directly addressed the hardware instead of making standard calls was faster, however, software addressing IBM PC hardware in this way would not run on MS-DOS machines with different hardware. The 808x computer marketplace rapidly excluded all machines which were not hardware-, the 640 KB barrier on conventional system memory available to MS-DOS is a legacy of that period, other non-clone machines, while subject to a limit, could exceed 640 kB. Rumors of lookalike, compatible computers, created without IBMs approval, by June 1983 PC Magazine defined PC clone as a computer accommodate the user who takes a disk home from an IBM PC, walks across the room, and plugs it into the foreign machine. Because of a shortage of IBM PCs that year, many customers purchased clones instead, Columbia Data Products produced the first computer more or less compatible to the IBM PC standard during June 1982, soon followed by Eagle Computer. Compaq announced its first IBM PC compatible in November 1982, the Compaq Portable, the Compaq was the first sewing machine-sized portable computer that was essentially 100% PC-compatible. The company could not copy the BIOS directly as a result of the decision in Apple v. Franklin. Each computer would have its own Original Equipment Manufacturer version of MS-DOS, any software written for MS-DOS would operate on any MS-DOS computer, despite variations in hardware design. This expectation seemed reasonable in the marketplace of the time. Until then Microsoft was based primarily on computer languages such as BASIC, the established small system operating software was CP/M from Digital Research which was in use both at the hobbyist level and by the more professional of those using microcomputers
41.
Commodore 1541
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The Commodore 1541 is a floppy disk drive which was made by Commodore International for the Commodore 64, Commodores most popular home computer. The best-known floppy disk drive for the C64, the 1541 is a single-sided 170-kilobyte drive for 5¼ disks, the 1541 directly followed the Commodore 1540. The disk drive uses group coded recording and contains a MOS Technology 6502 microprocessor, doubling as a disk controller, the number of sectors per track varies from 17 to 21. The drives built-in disk operating system is CBM DOS2.6, the 1541 was priced at under US$400 at its introduction. A C64 plus a 1541 cost about $900, while an Apple II with no disk drive cost $1295, the first 1541 drives produced in 1982 have a label on the front reading VIC-1541 and have an off-white case to match the VIC-20. In 1983, the 1541 was switched to having the familiar beige case, by 1983 a 1541 sold for $300 or less, much less than the price of other computers disk drives. After a brutal home-computer price war that Commodore began, the C64 and 1541 together cost under $500, the drive became very popular, and became difficult to find. The magazine reported in March 1984 that it received three defective drives in two weeks, and Compute. s Gazette reported in December 1983 that four of the magazines seven drives had failed, publications sorely needs additional 1541s for in-house use, yet we cant find any to buy. The early 1541s have a mechanism, and the disks often fail to release. This was fixed later when Commodore changed the vendor of the mechanism and adopted the flip-lever Newtronics mechanism. In addition, Commodore made the drives controller board smaller and reduced its chip count compared to the early 1541s, the beige-case Newtronics 1541 was produced from 1984-86. All but the very earliest non-II model 1541s can use either the Alps or Newtronics mechanism, visually, the first models, of the -VIC-1541 denomination, have an off-white color like the VIC-20 and VIC-1540. Then, to match the look of the C64, CBM changed the color to brown-beige. The 1541s numerous shortcomings opened a market for a number of third-party clones of the disk drive, well-known clones are the Oceanic OC-118 a. k. a. Excelerator+, the MSD Super Disk single and dual drives, the Enhancer 2000, the Indus GT, nevertheless, the 1541 became the first disk drive to see widespread use in the home and Commodore sold millions of the units. In 1986, Commodore released the 1541C, a version that offered quieter and slightly more reliable operation. It was replaced in 1988 by the 1541-II, which uses a power supply to provide cooler operation. Later ROM revisions fixed assorted problems, including a bug that made the save-and-replace command unusable
