Sinclair ZX Spectrum
Introduced April 1982 (16K and 48K versions)
The ZX Spectrum was by far the most widely known home computer of the 1980s - sold in their millions, it was truly a major upgrade over the ZX81 it replaced. Featuring colour and sound, and a lot more memory, it paved the way for home computer games as we know them today. Initially, in April 1982, there were two models available: The Spectrum 16K, available for £125 and the Spectrum 48K for £175, the only difference being the amount of RAM. Later, the 16K model's price was dropped to £99 and the 48K down to £129.
In October 1984, the Spectrum+ was released for £179.95 in order to address customer complaints over the rubber keyboard on the original Spectrum. Since the launch of the Spectrum it's looks had been somewhat revolutionary, but two years on it was looking small, insignificant, and dated. Furthermore, issues with the original's keyboard were well known, and a number of manufacturers were successfully selling third-party keyboards as replacements for the Spectrum rubber keyboard - Sinclair wanted to compete with them. This revised keyboard still used the underlying rubber membrane, but had more professional plastic key caps, not unlike those found on the Sinclair QL, released the same year. It also had a much larger space bar and Enter key.
Another positive addition was a reset button on the side of the casing. With the original spectrum no facility existed to power down or reset the machine, short of pulling the power plug out. Over time, this could cause the connector to become loose and reset itself inadvertently, so having a proper reset button was a big deal!
For existing Spectrum owners, the Spectrum+ keyboard could be purchased as a home-upgrade kit for £50.
Initially it was launched at the SIMO '85 trade show in Spain through Sinclair's Spanish distributor, Investrónica, not the home market of the UK. This was because Sinclair still had a large number of unsold 48K units in its warehouse, and wanted to ensure sales of the new system wouldn't impede the sale of existing stock. Investrónica had previously helped Sinclair adapt their Spectrum+ for the Spanish market, where the government had imposed a special tax on home computers below 64K that did not support the Spanish alphabet and support messages in Spanish. Sales of the 128 began in Spain in the second half of 1985, and in the UK half a year later, in January 1986 for a retail price of £179.95. Sadly this meant that they missed the important Christmas selling season for the new model.
The 128 machine boasted 128K of RAM, with this extra memory being 'paged' into the top 16K of memory when needed. It could also be used as a RAM disk, so several programs could be stored in memory at the same time.
It also got a new 3-channel sound chip in the form of the Yamaha AY-3-8912, which can also be found in the Vectrex, MSX, Amstrad CPC range, and Atari ST/STFM. It also received new peripheral ports on the back (MIDI compatibility for the AY-3-8912, RS232 serial port, and an RGB monitor port), plus an improved version of Sinclair BASIC. To support the new BASIC commands, it came with twice the ROM size (32K) of the earlier models. One key difference between the 128 and earlier models is the absence of an internal speaker. All audio is instead output via the Audio Out socket at the back.
In Spain, an external keypad was sold with the 128 which could be plugged into an RJ12 socket on the left hand side towards the front. This peripheral was supposed to retail for £19.95 in the UK, but was never made available. The later +2 ROM retained the routines for the keypad, and so it can support one. These routines were removed when Amstrad reworked the entire hardware and ROM for the +2A and +3.
Spanish 128s can be easily distinguished from their UK counterparts as they have a white '128K' logo, whilst English models have the logo in red.
In April 1986, shortly after the launch of the 128 in the UK, Amstrad PLC bought Sinclair Research, and continued the line with the release of the Spectrum +2 in 1987, which featured a built-in cassette recorder in the same way Amstrad's CPC464 had. and a proper typewriter-style keyboard. This keyboard also omitted the BASIC keywords seen on the Sinclair machines, with the exception of the commonly used LOAD, RUN, and CODE. Aside from these changes, it was essentially a Spectrum 128 inside. Just as with the Spectrum 128, the system offered a startup menu from which you could choose to boot into 48K BASIC (which still had the support for single keypress keyword entry) or 128K BASIC in which all words had to be keyed in full. The main menu screen lacked the 'Tape Test' the 128 had, and the ROM was altered to display 'Amstrad' in the copyright message on startup. Strangely, these ROM changes did introduce some compatibility issues with software that accessed ROM routines at specific addresses. The new unit also got two built-in joystick ports which were Sinclair Interface I standard, not Kempston).
Due to a reduction in production costs of the +2 over the 128, its retail price started at £149. The power supply provided with this new grey machine was a grey version of the same PSU supplied with the Spectrum+ and Spectrum 128.
The Spectrum +2 succeeded in reviving sales of the Spectrum line, commonly released in the "James Bond 007 Action Pack" which came complete with a lightgun and game based on the new James Bond film, the Living Daylights.
Amstrad's final major model release in the then struggling 8-bit home computer market was the Spectrum +3, released in 1988 at a retail price of £249. It replaced the +2's 'datacorder' with a built-in 3" floppy disk drive (similar to those used in Amstrad's CPC664 and 6128 computers) and got a black case. Only a small amount of software was officially released on floppy disk for the Spectrum, but many owners copied their cassette-based games to disk for the larger capacity and faster loading times. It was the only Spectrum model capable of running the CP/M operating system without external hardware.
It came with two new 16K ROM chips: one to hold the +3's disk operating system (a modified version of Amstrad's PCWDOS), called +3DOS, and another to hold the second part of the reorganised 128 ROM. These further ROM changes resulted in even more incompatibilities with some older 48K and 128K games, and the Interface 1 was now incompatible, so Microdrive units were not usable. The ZX Spectrum +3 power supply provides the same voltages as the one supplied with +2A/B. This power supply has the same DIN connector so can also be used with the +2A/B. However, the power supply purchased with the +3 had "Sinclair +3" written on the casing.
Around the same time, a revised version of the +2 was released, the Spectrum +2A, coinciding with a move of production facilities from Hong Kong to Taiwan. It was basically a +3 in terms of circuitry but with the +2 datacorder, and in a black case. The Spectrum +2A/+3 motherboard (Amstrad part number Z70830) was designed such that it could be assembled without the floppy disk controller or associated logic and in its place a +2 style "datacorder" connected. Originally, Amstrad planned to introduce an additional disk interface for the +2A called the AMSTRAD SI-1, however this never materialised. If an external disk drive was added, the "+2A" on the system OS menu would change to a +3.The +2A can be distinguished from a +2 not only by the colour of its case (black instead of grey), but also because the datacorder button decals are printed above the buttons not on the buttons themselves. On the rear, the +2A has a printer port and the power supply socket is a DIN-type connector rather than the older thin barrel-type connector. The power supply of the ZX Spectrum +2A used the same pinout as the +3, so they are 100% compatible. However, the power supply purchased with the +2A/B had "Sinclair +2" written on its casing.
Production of the +3 ceased in December 1990, believed to be in response to Amstrad relaunching their CPC range. At the time, it was estimated about 15% of ZX Spectrums sold had been +3 models. Production of the +2B (the only other model then still in production) continued, as it was believed not to be in competition with other computers in Amstrad's product range. It was eventually discontinued in 1992
Two other submodels were released called the ZX Spectrum +2B and ZX Spectrum +3B. These were functionally similar in design to the Spectrum +2A and +3 respectively. The main electronic differences were changes to the generation of the audio output signal to resolve problems with audio clipping and the removal of the external tape loading input on the +2B. Unlike the +2A and +3, the Spectrum +2B and +3B do not share a common motherboard. The +2B board (AMSTRAD part number Z70833) has no provision for floppy disk controller circuitry and the +3B motherboard (Amstrad part number Z70835) has no provision for connecting an internal tape drive.
The Sinclair ZX Spectrum was sold as a standalone computer by popular high-street retailers including WH Smith, Boots, and John Menzies, but also came bundled in a variety of packages. The following describes the more common ones:
ZX Spectrum News
08 April 2015Little Dragon 2 for Spectrum released
Courtesy of Gabriele (Gabam) and Neil Parsons, here is a long awaited title - Little Dragon 2, a homebrew platformer for the ZX Spectrum.
13 January 2015New version of Zero Spectrum emulator v0.7
A new version of Zero, a ZX Spectrum emulator for Windows has just been released today. This version 0.7 adds full support for SZX specification 1.4 files, loads of command-line arguments added for execution from front ends, correct cold boot and reset emulation, shortcut keys for major emulator functions, fully resizable game window, and many many issues fixed.
02 December 2014Sinclair Spectrum Games Console to be Crowdfunded
The much beloved Sinclair ZX Spectrum is to be relaunched as a retro gaming console. It is the work of an Indiegogo project which has been endorsed by Sir Clive Sinclair himself.
02 October 2014Square Sounds Tokyo 2014 ZX Concert Music
There was a chiptune festival in Japan – Square Sounds Tokyo 2014 – here is the video of yerzmyey's ZX concert there, on 28th Sep 2014.
30 August 2014Spectrum Today #0 - now in English
The first issue of Spectrum Today has now been translated from Slovak into English.