ZX Spectrum
From Retrocomputing Wiki
| ZX Spectrum | |
|---|---|
| Manufacturer | Sinclair Research |
| Type | Home computer |
| Released | 23 April 1982 |
| Introductory price | £125 (16 KB), £175 (48 KB) |
| Discontinued | 1992 |
| CPU | Zilog Z80A at 3.5 MHz |
| Memory | 16 KB or 48 KB RAM, 16 KB ROM |
| Storage | Cassette; ZX Microdrive via Interface 1 |
| Display | 256 × 192, 15 colours, colour attributes per 8 × 8 cell |
| Sound | 1-bit beeper |
| Operating system | Sinclair BASIC in ROM |
The ZX Spectrum is an 8-bit home computer released in the United Kingdom by Sinclair Research on 23 April 1982. It followed the black-and-white Sinclair ZX81 and was Sinclair's first colour computer. Cheap, small and easy to program, it became the best-selling computer in Britain in the early 1980s and was the machine on which a large part of the British games industry got its start. Its fans often call it the Speccy.
Contents |
[edit] Design
The Spectrum was designed by Richard Altwasser, who did the electronics, and Rick Dickinson, who designed the case and the keyboard. The ROM, containing Sinclair BASIC, was written by Steve Vickers and John Grant of Nine Tiles. To keep the price down the machine uses an uncommitted logic array (ULA) made by Ferranti in place of dozens of separate chips, and it was assembled under contract by Timex in Dundee, Scotland.
The original model has a keyboard of grey rubber keys, which gave it the nickname "dead flesh" keyboard. Each key carries up to six functions, and BASIC keywords are entered with a single keypress: pressing P in the right mode types PRINT, for example. This saved memory and typing, but took some getting used to.
[edit] Graphics and sound
The screen is 256 × 192 pixels with eight colours, each in a normal and a bright version (black looks the same in both, so there are 15 distinct colours). To save memory, colour is stored separately from the pixels, with one ink and one paper colour for each block of 8 × 8 pixels. When two differently coloured objects overlap the same block, one of them changes colour. This effect is known as attribute clash or colour clash and is one of the most recognisable things about Spectrum games. Many games avoided it by using only one colour for the playing area.
Sound comes from a small beeper driven directly by the processor. Clever programmers managed to get two or more channels of music out of it, but the processor could do little else while doing so.
[edit] Storage
Programs were normally loaded from ordinary audio cassettes, which took several minutes for a large game and did not always work the first time. In 1983 Sinclair introduced the ZX Microdrive, a fast tape loop cartridge drive that connected through the Interface 1, which also added an RS-232 port and a simple local network.
[edit] Models
| Model | Year | Notes |
|---|---|---|
| ZX Spectrum 16K / 48K | 1982 | rubber keyboard |
| ZX Spectrum+ | 1984 | hard plastic keys and a reset button, 48 KB |
| ZX Spectrum 128 | 1985 (Spain), 1986 (UK) | 128 KB, AY-3-8912 sound chip, improved BASIC |
| ZX Spectrum +2 | 1986 | Amstrad model with built-in cassette recorder |
| ZX Spectrum +3 | 1987 | Amstrad model with a 3-inch floppy disk drive |
In April 1986 Sinclair Research sold its computer business and the Sinclair brand to Amstrad, which made the +2 and +3 and kept the Spectrum in production until 1992. In the United States a modified version was sold as the Timex Sinclair 2068, without much success. Unlicensed clones were built in large numbers in Eastern Europe and the Soviet Union.
[edit] Software
Several thousand games were published for the Spectrum, many of them written by one or two people in their bedrooms. Well-known titles include Manic Miner and Jet Set Willy by Matthew Smith, Knight Lore and Sabre Wulf by Ultimate Play the Game, Skool Daze, Head Over Heels and the Spectrum version of Elite. Many later British developers, including Rare, the company that grew out of Ultimate, began on the Spectrum.
Spectrum emulators are available for almost every modern platform, and the World of Spectrum website keeps a large archive of the machine's software, with permission from many of the original publishers.
