ZX SPECTRUM

The Sinclair ZX Spectrum was a small home computer released in the United Kingdom in 1982 by Sinclair Research. Based on a Zilog Z80 CPU running at 3.54 MHz, the Spectrum came with either 16KB or 48KB of RAM (an expansion pack was also available to upgrade the former). Video output was to a TV, for a simple colour graphic display. The rubber keyboard (on top of a membrane, similar to calculator keys) was marked with Sinclair BASIC programming language keywords, so that pressing, say, "G" when in programming mode would insert the BASIC command GOTO. Programs and data were stored using a normal cassette recorder.

The Spectrum's video display, although rudimentary by today's standards, was perfect at the time for display on portable TV sets, and didn't present a much of a barrier to game development. The text mode display was 32 columns × 24 rows, with a choice of 8 colours in either normal or bright mode, which gave 16 shades. The graphics resolution was 256×192 with the same colour limitations. The Spectrum had an interesting method of handling colour; the colour attributes were held in a 32×24 grid, separate from the text or graphical data, but was still limited to only two colours in any given character cell. This led to what was called colour clash or attribute clash with some bizarre effects in arcade style games.

Retailing for £125125 for the 16KB and £175 for the 48KB model, the Spectrum was the first mainstream audience home computer in the UK, similar in significance to the Commodore 64 in the USA (the C64 also being the main rival to the Spectrum in the UK market). A slightly modified version of the Spectrum, in a silver colored case with hard plastic keys, was marketed in the USA by Timex as the TS2068. It had an extra 8K extension ROM and a cartridge port, as well as two joystick ports and a AY-3-8912 sound chip with extra Sinclair BASIC commands to support these devices (STICK and SOUND, respectively).

Several peripherals for the Spectrum were marketed by Sinclair: the printer was already on the market, as the Spectrum had retained the protocol for the ZX81's printer. The Interface 1 added a standard RS-232 serial port, a proprietary format local area networking port, and the ability to connect up to eight ZX Microdrives – somewhat unreliable but speedy tape-loop storage devices that was later used in a revised version on the Sinclair QL (the QL's Microdrive data storage format was electrically compatible but logically incompatible with the Spectrum's). Sinclair also released the Interface 2 which added two joystick ports and a ROM cartridge port.

There were also a plethora of third-party hardware addons. These more well-known of these included the Kempston joystick interface, the Currah Microspeech unit (speech synthesis), and the Multiface (snapshot and disassembly tool), from Romantic Robot. There were numerous disk drive interfaces, including the Opus Discovery and the Disciple/Plus D from Miles Gordon Technology. During the mid-80s, the company Micronet800 launched a service allowing users to connect their ZX Spectrums to a network known as Prestel. This service had some similarities to the Internet, but was proprietary and fee-based.

A number of current leading games developers and development companies began their careers on the ZX Spectrum, including Peter Molyneux (ex-Bullfrog Games), Shiny Entertainment, and Ultimate Play The game (now known as Rare, Inc, maker of many famous titles for the Super NES and Nintendo 64 game consoles).

Successor models of the basic Spectrum included the ZX Spectrum+, with an improved keyboard, and the ZX Spectrum 128, with the improved keyboard, three-channel sound, 128KB of RAM, and RGB monitor output. After Amstrad's buyout of Sinclair Research in 1986, two more versions were released: the ZX Spectrum +2 (with a built-in cassette recorder, like the Amstrad CPC 464) and the ZX Spectrum +3 (with a built-in 3-inch floppy disk drive, like the Amstrad CPC 6128). Many Spectrum clones were produced, especially in Eastern Europe and South America. Some of them are still being produced such as Didaktik and the Sprinter from Peters Plus Ltd. A Russian clone of the ZX Spectrum is the Pentagon.

See also: Sinclair ZX80, ZX81, SAM Coupe, ZX Spectrum Demos, History of computing hardware II.

External links

• World of Spectrum
• Jasper - An online spectrum emulator written in Java