Online Encyclopedia Search Tool

Your Online Encyclopedia

 

Online Encylopedia and Dictionary Research Site

Online Encyclopedia Free Search Online Encyclopedia Search    Online Encyclopedia Browse    welcome to our free dictionary for your research of every kind

Online Encyclopedia



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 3.50 MHz, the Spectrum came with either 16KB or 48KB of RAM (an expansion pack was also available to upgrade the former). The hardware designer was Richard Altwasser of Sinclair Research and the software was written by Steve Vickers (on contract from Nine Tiles Ltd, the authors of Sinclair BASIC). Sinclair's industrial designer Rick Dickinson was responsible for the machine's outward appearance. Originally dubbed the ZX82, the machine was later renamed the "Spectrum" by Sinclair to highlight the machine's colour display, compared to the black-and-white of its predecessors the ZX80 and ZX81.

ZX Spectrum+
Enlarge
ZX Spectrum+
Contents

Description


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 much of a barrier to game development. The text mode display was 32 columns × 24 rows of characters from the Spectrum Character Set, with a choice of 8 colours in either normal or bright mode, which gave 15 shades (black was the same in both modes). 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.

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). An enhanced version of the Spectrum with better sound, graphics and other modifications was marketed in the USA by Timex as the TS2068.

A number of current leading games developers and development companies began their careers on the ZX Spectrum, including Peter Molyneux (ex-Bullfrog Games), Dave Perry of Shiny Entertainment, and Ultimate Play The Game (now known as Rare, Inc, maker of many famous titles for Nintendo game consoles). Other prominent games developers include Matthew Smith (Manic Miner, Jet Set Willy), and Jon Ritman (Match Day, Head over Heels).

Models

ZX Spectrum (1982)

Released by Sinclair in 1982 and available with either 16KB (£125, later £99) or 48KB (£175, later £129) of RAM and 16KB ROM. Remembered for its rubber keyboard and diminutive size. Owners of the 16K model could purchase an external 32K RAMpack that mounted in the rear expansion slot. As with the ZX81, "RAMpack wobble" caused by poor connection with the expansion was the bane of many users, causing instant crashes.

ZX Spectrum+ (1984)

The 48K Spectrum gets a much needed solid keyboard and reset button, retailing for £180. An upgrade package for older machines was also available.

ZX Spectrum 128 (1986)

The last Spectrum to be produced by Sinclair (although developed by Investronica of Spain) and based on the Spectrum+. New features included three-channel audio via the AY-3-8912 chip, MIDI compatibility, 128 KB of paging RAM, an RS-232 serial port and an RGB monitor output.

ZX Spectrum +2 (1986)

Shortly after Amstrad's buyout of Sinclair Research in 1986 came the ZX Spectrum +2. It featured a new casing coloured grey, distinguishing itself from the familiar black of previous Spectrums. The new case also integrated a new spring loaded keyboard, dual joystick ports, and a built-in cassette recorder dubbed the "Datacorder" (like the Amstrad CPC 464). Production cost cutting saw the retail price drop to £139-£149. Aside from the tape drive, revised keyboard and casing the +2 was essentially the same as the 128 model.

ZX Spectrum +2A / +2B (1987)

The +2A was produced to homogenize Amstrad's range. Although the case still reads "ZX Spectrum +2", the +2A/B is easily distinguishable from a +2 as the case was restored to the standard Spectrum black.

The +2A was derived from Amstrad's new +3 model (see below), with a new motherboard which vastly reduced the chip count, integrating many of them into a new ASIC. The +2A replaced the +3's disk drive and associated hardware with a tape drive, as in the original +2. Originally, Amstrad planned to introduce an additional disk interface, but this never appeared.

The +2A was intended to merely be a cost-reduced, bug-fixed version of the original +2, but the other hardware and ROM changes inherited from the +3 - removal of the code to drive the MIDI port and external keypad, support for the disk controller and so on - rendered it incompatible with much original Spectrum hardware, such as many external storage interfaces.

ZX Spectrum +3 (1987)

Amstrad produced disk version based on the +2 but featuring a built-in 3-inch floppy disk drive (like the Amstrad CPC 6128). Most models featured distorted sound thanks to a design fault later rectified in the "4.1 ROM" model. Retailed for £249 then later £199 and the only model capable of running CP/M without additional hardware.

Clones

Sinclair licensed the Spectrum design to Timex in the USA who produced their own, largely incompatible, derivatives.

In the UK Spectrum peripheral vendor Miles Gordon Technology (MGT) released the SAM Coupe as the natural successor with some Spectrum compatibility however the Commodore Amiga and Atari ST had taken hold of the market by this point leaving MGT in eventual receivership.

Many unofficial 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 . Russian clones include the Hobbit, Pentagon and Scorpion.

Peripherals

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 (later used in a revised version on the Sinclair QL, whose 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. The 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/PlusD 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.

See also

External links

  • World of Spectrum http://www.worldofspectrum.org/
  • comp.sys.sinclair FAQ http://www.worldofspectrum.org/faq/
  • Category at ODP http://dmoz.org/Computers/Systems/Sinclair/ZX_Spectrum/
  • Jasper - An online spectrum emulator written in Java http://www.spectrum.lovely.net/
  • RWAP Software - second hand items and spares http://www.rwapsoftware.co.uk/
  • ZX Planet - Spectrum Heaven http://zxplanet.emuunlim.com/
  • XZX-Pro - A ZX Spectrum emulator for UNIX/Linux/Mac OS X http://www.zx-spectrum.net/
  • old-computers.com - page on the spectrum http://www.old-computers.com/museum/computer.asp?st=1&c=223
  • Scans of original ZX Spectrum promotional materials ftp://ftp.earth.ox.ac.uk/pub/speccy/


Sinclair computers, derivatives, and clones (ZX80/81, ZX Spectrum, and QL clones)

By Sinclair Research and AmstradZX80 | ZX81 | ZX Spectrum, Spectrum+, Spectrum 128, +2 and +3 (the latter two by Amstrad) | Sinclair QL
By others: Timex Sinclair 1000 | TS 1500 | TS 2048 | TS 2068 | SAM Coupé | Didaktik | Hobbit | Sprinter | Pentagon



Last updated: 02-10-2005 09:40:06
Last updated: 02-28-2005 01:46:07