Sinclair ZX Spectrum
Introduced April 1982 (16K and 48K versions)
In the UK, 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 connector out. Over time, this could cause the connector to become loose and reset the computer 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/composite 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 MIC socket on the side.
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, as in the picture above.
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 commands. 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 minor 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 one supplied with the Spectrum + and Spectrum 128.
The Spectrum +2 succeeded in reviving sales of the Spectrum line, commonly bundled in the "James Bond 007 Action Pack" which came complete with a lightgun and game based on the newly released 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.
Just after the +3 release, 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 a simplified +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 beeper being much louder than the AY chip's output, 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. Externally, you cannot tell a +2B over a +2A, nor a +3B over a +3. Each have the same ports.
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:
Which One to Buy?
The original rubber-keyboard variant got 9 different motherboard revisions in its life, the first two of which were for both the 16K and 48K model, and the later 7 were 48K model only. Get the latest 'Issue' board you can - the last one was Issue 6 - but certainly get an Issue 3 or later. The main problem on all of these is the keyboard membrane, which can crack over the years. You can buy new replacement membranes from RWAP Software for a reasonable price.
The Spectrum 128 only had 1 board revision. These are very compatible with 128K games, but suffer from quite a bit of incompatibility with 48K games, primarily due to the revised ROM where a lot of games made use of the empty portion at the end of the 48K's ROM and on the 128 this area was used for the optional keypad interface.
Generally-speaking, +2 models (grey) with the original +2 motherboard had some manufacturing faults (one board revision had 3 transistors installed the wrong way around), and tend to slightly be less reliable than the +2A/+2B/+3/+3B models. The biggest problem with the +2A, +2B, +3 and +3B models is if the power supply becomes faulty - it is uncommon for them to fail, but there isn't an easy off-the-shelf replacement for them. Most are easy to fix if you have some soldering skills. The +2 (grey) models used a standard 9V barrel-type power socket just like the 128, so if the original fails you can pick up a replacement very easily.
For the best games compatibility on +2 models and beyond, most recommend the original +2 (grey). Having said that, many games have now been patched or modified to work over the years on +2A and beyond. For the best picture quality,
So You Bought One
If you just rediscovered your vintage Speccy in the attic, or bought one used, here are some tips to help you get back into the Spectrum goodness. Head over to the 'How to Use' page for details on how to get your computer up and running.
If you're actively using a ZX Spectrum in modern times, consider purchasing an SD storage interface, such as the DivMMC EnJOY! This completely replaces your cassette recorder with the ability to store and retrieve programs from an SD card. It plugs into the expansion slot and is compatible with all models of ZX Spectrum (16K up to +3B). The latest version even has a built-in joystick interface which supports Kempston and Sinclair modes - especially handy if you have a +2 or later since those got the funky Amstrad rewiring that made Atari-style joysticks incompatible. By using an SD card interface and downloaded Spectrum titles in .TAP, .SNA, or .TRD format, this saves wear and tear on your original cassettes, offers instant loading times, plus a variety of added extras.
Upgrades and Repairs
There are a number of things you can do to improve your Spectrum and keep it ticking for many more years. Here are just some:
In 2020 the first of a new breed of Sinclair ZX Spectrums was finally shipped to Kickstarter backers after nearly 3 years in development - the ZX Spectrum Next. Now into its second Kickstarter campaign (11th August 2020), the product has had more than 5,000 backers and more than £1.5 million invested in it. Go to our dedicated ZX Spectrum Next page to read more!
ZX Spectrum News
16 September 2021Sir Clive Sinclair: Computing pioneer dies aged 81
It is with a sad heart that we report that Sir Clive Sinclair died this morning.
12 April 20212 New Titles from Double Sided Games
Double Sided Games has added two great games to their catalogue: Don’t Break The Balls for the Commodore 64 and Vegetables Deluxe for the ZX Spectrum.
20 December 2020Quadron Deluxe Announced!
Cronosoft are about to release a Deluxe version of Andy Beale's game, Quadron.
12 August 2020ZX Spectrum Next Issue 2 Kickstarter Begins
If you missed out on backing the first Kickstarter campaign for the Sinclair ZX Spectrum Next in 2017, now's your chance!
29 June 2020Rite of Druid – A new text adventure game for the ZX Spectrum Next is available now
Rite of the Druid is a text adventure game or using a more modern term, interactive fiction where you are part of a small tribe, preparing to take part in a ritual that will allow you to become a full druid. You are transported to a strange land where you must find the rune of power and return to complete the rite.