Glossary of Terms


6845 CRT

A Cathode Ray Tube Controller IC from Motorola, designed to generate the signals necessary to interface with a raster display. Used in the Amstrad CPC, Acorn BBC, and IBM PC MDA and CGA cards. See also the related MOS Technology 6545.


(see Intel 8255)


(see AY-3-8912)


Ad Lib

The Ad Lib used Yamahas YM3812 sound chip which produces sound via FM synthesis. Digital audio (PCM) was not supported, a key feature supported by later competition (such as the Creative Labs Sound Blaster).

AMSDOS (Amstrad Disk Operating System)

AMSDOS is a disk operating system for the 8-bit Amstrad CPC Computer (and various clones). It first appeared in 1984 on the CPC464, with added 3-inch disk drive, and then on the CPC664 and CPC 6128. AMSDOS was provided built-in to ROM (either supplied with the external disk drive or in the machine ROM, depending on model) and was accessible through the built-in Locomotive BASIC as well as through firmware routines. Its main function was to map the cassette access routines (which were built-in to every CPC model) through to a disk drive. This enabled the majority of cassette-based programs to work with a disk drive with no modification. AMSDOS was able to support up to two connected disk drives.AMSDOS (Amstrad Disk Operating System)


The codename of the Amstrad CPC range of computers during development. Arnold = CPC464, Arnold 2 = CPC664, Arnold 3 = CPC6128, Arnold 4 = Cost-reduced CPC464 and CPC6128, Arnold 5 = CPC464+ and CPC6128+


The PC/AT (Advanced Technology) was IBM's second generation of Personal Computer (PC), launched in 1984 with the brand new Intel 80286 CPU running at 6 MHz.


A 3-voice Programmable Sound Generator chip developed by General Instrument in the early 1980s. It was used in the Intellivision and Vectrex video game consoles and the MSX, Atari ST, Amstrad CPC, Oric 1, Colour Genie, Elektor TV Games Computer and Sinclair ZX Spectrum 128/+2/+3 home computers as well as the Mockingboard sound card for the Apple II family.



CGA (Colour Graphics Adapter)

IBMs first colour graphics card, and the first colour computer display standard for the IBM PC. A CGA card featured several graphics and text modes. The highest resolution of any mode was 640×200, and the highest colour depth supported was 4-bit (16 colours) with the most commonly used combination of 320x200 with 4 colours.


A parallel data interface named after the U.S. company that developed it. The Centronics parallel port began life as a 36-pin ribbon cable connector, but was later changed to the more common 25-pin connector when IBM used them on their PC range, resulting in the now familiar parallel cable with a DB25M at one end and a 36-pin micro ribbon connector at the other.

CP/M (Control Program for Microcomputers)

An operating system originally created for Intel 8080/85-based microcomputers by Gary Kildall of Digital Research, Inc. Initially confined to single tasking on 8-bit processors and no more than 64K of memory, later versions of CP/M added multi-user variations, and were migrated to 16-bit processors. CP/M would also run on systems based on the Zilog Z80 processor since the Z80 was able to execute 8080 code.


DOS Plus (DOS+)

An operating system written by Digital Research, first released in 1985. It can be seen as an intermediate step between CP/M-86 and DR-DOS. It is able to run programs written for either CP/M-86 or MS-DOS 2.11. Like MS-DOS, it has a command-line interpreter called COMMAND.COM. There is an AUTOEXEC.BAT file, but no CONFIG.SYS. The major difference the user will notice is that the bottom line of the screen contains status information.


LOGO (Logic Oriented Graphic Oriented) is a programming language used for functional programming. It is an adaptation and dialect of the LISP language; some have called it Lisp without the parentheses. Today, it is known mainly for its turtle graphics, but it also has significant facilities for handling lists, files, I/O, and recursion.


EGA (Enhanced Graphics Adapter)

The IBM PC computer display standard specification located between CGA and VGA in terms of colour and space resolution. Introduced in 1984 by IBM for its new PC-AT, EGA produces a display of 16 simultaneous colours from a palette of 64 at a resolution of up to 640×350 pixels. The EGA card includes a 16K ROM to extend the system BIOS for additional graphics functions and includes the Motorola MC6845 video address generator as used in the CGA.

EPROM (Erasable Programmable Read-Only Memory)

A type of memory chip that retains its data when its power supply is switched off. In other words, it is non-volatile. It is an array of floating-gate transistors individually programmed by an electronic device that supplies higher voltages than those normally used in digital circuits. Once programmed, an EPROM can be erased only by exposing it to strong ultraviolet light.



GEM (Graphical Environment Manager)

A windowing system created by Digital Research, Inc. for use with the CP/M operating system on the Intel 8088 and Motorola 68000 CPUs. Later versions ran over DOS as well, bundled with PCs from Amstrad. It was also formed the basis for the GUI used on the Atari ST.


A games console-version of the Amstrad CPC464, released in 1990.



Intel 8255

A Programmable Peripheral Interface chip originally developed for use with the Intel 8085 and 8086 CPUs. It is used to give the CPU access to programmable parallel I/O, and is similar to other such chips like the Motorola 6520 PIA (Peripheral Interface Adapter), the MOS Technology 6522 (Versatile Interface Adapter) and the MOS Technology CIA (Complex Interface Adapter) all developed for the 6502 CPU family.




Locomotive [Software]

A British company founded in 1983. They wrote the BASIC interpreter for the Amstrad CPC series of computers, and supporting software including LocoScript word processor for the PCW range and PCs.


MCGA (Multi-Colour Graphics Array)

MCGA was similar to VGA in that it had a 256-color mode, but that was the extent of the chipsets abilities. Display modes supported by MCGA were all CGA modes plus 640×480 monochrome, 60 Hz refresh rate, and 320×200, 256 colors (out of a palette of 262,144) at 70 Hz refresh rate. One might consider MCGA to be a stepping stone between CGA and VGA (MCGA lacked EGA compatibility, while VGA, on the other hand, was fully backwards compatible)

MDA (Monochrome Display Adapter)

IBMs standard video display card and computer display standard for the PC, introduced in 1981. The MDA did not have any graphics mode of any kind; it only featured a single monochrome text mode (PC video mode 7), which could display 80 columns by 25 lines of high resolution text characters. It had 4K of video memory.







Sound Blaster

Soon after the introduction of the AdLib Music Card, competition arrived with the Creative Labs Sound Blaster in 1989. As well as its forebear's (Game Blaster) features, it had an 11-voice FM synthesizer using the Yamaha YM3812 chip, also known as OPL2. The Sound Blaster was fully compatible with AdLib, meaning it would play any past, present, and future game written for AdLib's own card. And it added 2 key features: a PCM audio channel, and a game port. PCM audio could record and play digital-audio recordings, which included dialogue, sound effects, and short musical performances. PCM audio complemented the YM3812, allowing game developers to include digital-audio for realistic sound-effects and speech that could not be adequately reproduced by the Yamaha's FM synthesis. And the Sound Blaster's inclusion of a game-port made it a single-card gaming solution.




VGA (Video Graphics Array)

The name given to video display hardware first introduced with the IBM PS/2 line of computers in 1987, although through its widespread adoption the term 'VGA' has also come to mean either an analog computer display standard, the 15-pin D-subminiature VGA connector or the 640×480 resolution itself. VGA supported both 16-colour and 256-colour modes from a palette of 262,144 colours.