ZX Spectrum

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ZX Spectrum
An issue 2 1982 ZX Spectrum
Developer Sinclair Research
Manufacturer Timex Corporation
Type Home computer
Generation 8-bit
Release dateUnited Kingdom: 23 April 1982
(37 years ago)
Discontinued1992 [1]
Units sold5 million
Media Cassette tape, 3-inch floppy disk on Spectrum +3
CPU Z80 @ 3.5 MHz and equivalent
Memory16  KB  / 48 KB / 128 KB
Predecessor ZX81
Successor QL

The ZX Spectrum ( UK: /zɛdɛksˈspɛktrəm/ ) is an 8-bit personal home computer released in the United Kingdom in 1982 by Sinclair Research.

British English is the standard dialect of English language as spoken and written in the United Kingdom. Variations exist in formal, written English in the United Kingdom. For example, the adjective wee is almost exclusively used in parts of Scotland and Ireland, and occasionally Yorkshire, whereas little is predominant elsewhere. Nevertheless, there is a meaningful degree of uniformity in written English within the United Kingdom, and this could be described by the term British English. The forms of spoken English, however, vary considerably more than in most other areas of the world where English is spoken, so a uniform concept of British English is more difficult to apply to the spoken language. According to Tom McArthur in the Oxford Guide to World English, British English shares "all the ambiguities and tensions in the word 'British' and as a result can be used and interpreted in two ways, more broadly or more narrowly, within a range of blurring and ambiguity".

In computer architecture, 8-bit integers, memory addresses, or other data units are those that are 8 bits wide. Also, 8-bit CPU and ALU architectures are those that are based on registers, address buses, or data buses of that size. 8-bit is also a generation of microcomputers in which 8-bit microprocessors were the norm.

Home computer class of microcomputers

Home computers were a class of microcomputers that entered the market in 1977, that started with what Byte Magazine called the "trinity of 1977", and which became common during the 1980s. They were marketed to consumers as affordable and accessible computers that, for the first time, were intended for the use of a single nontechnical user. These computers were a distinct market segment that typically cost much less than business, scientific or engineering-oriented computers of the time such as the IBM PC, and were generally less powerful in terms of memory and expandability. However, a home computer often had better graphics and sound than contemporary business computers. Their most common uses were playing video games, but they were also regularly used for word processing, doing homework, and programming.


Referred to during development as the ZX81 Colour and ZX82, [2] [3] it was launched as the ZX Spectrum by Sinclair to highlight the machine's colour display, compared with the black and white of its predecessor, the ZX81. [4] The Spectrum was released as eight different models, ranging from the entry level with 16  KB RAM released in 1982 to the ZX Spectrum +3 with 128 KB RAM and built in floppy disk drive in 1987; together they sold over 5 million units worldwide (not counting clones). [5]

Black and white monochrome form in visual arts

Black-and-white images combine black and white in a continuous spectrum, producing a range of shades of gray.

ZX81 home computer produced by Sinclair Research

The ZX81 is a home computer that was produced by Sinclair Research and manufactured in Dundee, Scotland, by Timex Corporation. It was launched in the United Kingdom in March 1981 as the successor to Sinclair's ZX80 and was designed to be a low-cost introduction to home computing for the general public. It was hugely successful, and more than 1.5 million units were sold before it was discontinued. The ZX81 found commercial success in many other countries, notably the United States where it was initially sold as the ZX-81. Timex manufactured and distributed it under licence and enjoyed a substantial but brief boom in sales. Timex later produced its own versions of the ZX81 for the US market: the Timex Sinclair 1000 and Timex Sinclair 1500. Unauthorized clones of the ZX81 were produced in several countries.

The kilobyte is a multiple of the unit byte for digital information.

The Spectrum was among the first mainstream-audience home computers in the UK, similar in significance to the Commodore 64 in the US. The introduction of the ZX Spectrum led to a boom in companies producing software and hardware for the machine, [6] the effects of which are still seen. [1] Some credit it as the machine which launched the UK IT industry. [7] Licensing deals and clones followed, and earned Clive Sinclair a knighthood for "services to British industry". [8]

Commodore 64 8-bit home computer introduced in 1982

The Commodore 64, also known as the C64 or the CBM 64, is an 8-bit home computer introduced in January 1982 by Commodore International. It has been listed in the Guinness World Records as the highest-selling single computer model of all time, with independent estimates placing the number sold between 10 and 17 million units. Volume production started in early 1982, marketing in August for US$595. Preceded by the Commodore VIC-20 and Commodore PET, the C64 took its name from its 64 kilobytes(65,536 bytes) of RAM. With support for multicolor sprites and a custom chip for waveform generation, the C64 could create superior visuals and audio compared to systems without such custom hardware.

Software Non-tangible executable component of a computer

Computer software, or simply software, is a collection of data or computer instructions that tell the computer how to work. This is in contrast to physical hardware, from which the system is built and actually performs the work. In computer science and software engineering, computer software is all information processed by computer systems, programs and data. Computer software includes computer programs, libraries and related non-executable data, such as online documentation or digital media. Computer hardware and software require each other and neither can be realistically used on its own.

Computer hardware physical components of a computer

Computer hardware includes the physical, tangible parts or components of a computer, such as the cabinet, central processing unit, monitor, keyboard, computer data storage, graphics card, sound card, speakers and motherboard. By contrast, software is instructions that can be stored and run by hardware. Hardware is so-termed because it is "hard" or rigid with respect to changes or modifications; whereas software is "soft" because it is easy to update or change. Intermediate between software and hardware is "firmware", which is software that is strongly coupled to the particular hardware of a computer system and thus the most difficult to change but also among the most stable with respect to consistency of interface. The progression from levels of "hardness" to "softness" in computer systems parallels a progression of layers of abstraction in computing.

The Commodore 64, Dragon 32, Oric-1, Oric Atmos, BBC Micro and later the Amstrad CPC range were rivals to the Spectrum in the UK market during the early 1980s. While the machine was officially discontinued in 1992, [1] new software titles continue to be released  over 40 so far in 2019. [9]

BBC Micro series of microcomputers by Acorn

The British Broadcasting Corporation Microcomputer System, or BBC Micro, is a series of microcomputers and associated peripherals designed and built by the Acorn Computer company in the 1980s for the BBC Computer Literacy Project, operated by the British Broadcasting Corporation. Designed with an emphasis on education, it was notable for its ruggedness, expandability, and the quality of its operating system. An accompanying 1982 television series, The Computer Programme, featuring Chris Serle learning to use the machine, was broadcast on BBC2.

Amstrad CPC series of home computers produced by Amstrad

The Amstrad CPC is a series of 8-bit home computers produced by Amstrad between 1984 and 1990. It was designed to compete in the mid-1980s home computer market dominated by the Commodore 64 and the Sinclair ZX Spectrum, where it successfully established itself primarily in the United Kingdom, France, Spain, and the German-speaking parts of Europe.


ZX Spectrum 48K motherboard (Issue 3B - 1983, heat sink removed) ZXspectrum mb.jpg
ZX Spectrum 48K motherboard (Issue 3B  1983, heat sink removed)

The Spectrum is based on a Zilog Z80 A CPU running at 3.5  MHz (or NEC D780C-1 clone). The original model has 16 KB (16×1024 bytes) of ROM and either 16 KB or 48 KB of RAM. Hardware design was by Richard Altwasser of Sinclair Research, and the outward appearance was designed by Sinclair's industrial designer Rick Dickinson. [6]

Zilog Z80 8-bit microprocessor

The Z80 is an 8-bit microprocessor introduced by Zilog as the startup company's first product. The Z80 was conceived by Federico Faggin in late 1974 and developed by him and his 11 employees starting in early 1975. The first working samples were delivered in March 1976, and it was officially introduced on the market in July 1976. With the revenue from the Z80, the company built its own chip factories and grew to over a thousand employees over the following two years.

Central processing unit Central component of any computer system which executes input/output, arithmetical, and logical operations

A central processing unit (CPU), also called a central processor or main processor, is the electronic circuitry within a computer that carries out the instructions of a computer program by performing the basic arithmetic, logic, controlling, and input/output (I/O) operations specified by the instructions. The computer industry has used the term "central processing unit" at least since the early 1960s. Traditionally, the term "CPU" refers to a processor, more specifically to its processing unit and control unit (CU), distinguishing these core elements of a computer from external components such as main memory and I/O circuitry.

NEC Japanese technology corporation

NEC Corporation is a Japanese multinational information technology and electronics company, headquartered in Minato, Tokyo, Japan. The company was known as the Nippon Electric Company, Limited, before rebranding in 1983 as NEC. It provides IT and network solutions to business enterprises, communications services providers and to government agencies, and has also been the biggest PC vendor in Japan since the 1980s with the PC-8000 series.

Video output is through an RF modulator and was designed for use with contemporary television sets, for a simple colour graphic display. Text can be displayed using 32 columns × 24 rows of characters from the ZX Spectrum character set or from a set provided within an application, from a palette of 15 shades: seven colours at two levels of brightness each, plus black. [10] The image resolution is 256×192 with the same colour limitations. [11] To conserve memory, colour is stored separate from the pixel bitmap in a low resolution, 32×24 grid overlay, corresponding to the character cells. In practice, this means that all pixels of an 8x8 character block share one foreground colour and one background colour. Altwasser received a patent for this design. [12]

RF modulator

An RF modulator is an electronic device whose input is a baseband signal which is used to modulate a radio frequency source.

Television Telecommunication medium for transmitting and receiving moving images

Television (TV), sometimes shortened to tele or telly, is a telecommunication medium used for transmitting moving images in monochrome, or in colour, and in two or three dimensions and sound. The term can refer to a television set, a television program, or the medium of television transmission. Television is a mass medium for advertising, entertainment and news.

ZX Spectrum character set

The ZX Spectrum character set is the variant of ASCII used in the British Sinclair ZX Spectrum family computers. It is based on ASCII-1967 but the characters ^, ` and DEL are replaced with ↑, £ and ©. It also differs in its use of the C0 control codes other than the common BS and CR, and it makes use of the 128 high-bit characters beyond the ASCII range. The ZX Spectrum's main set of printable characters and system font are also used by the Jupiter Ace computer.

An "attribute" consists of a foreground and a background colour, a brightness level (normal or bright) and a flashing "flag" which, when set, causes the two colours to swap at regular intervals. [11] This scheme leads to what was dubbed colour clash or attribute clash , where a desired colour of a specific pixel could not necessarily be selected. This became a distinctive feature of the Spectrum, meaning programs, particularly games, had to be designed around this limitation. Other machines available around the same time, for example the Amstrad CPC or the Commodore 64, did not suffer from this limitation. The Commodore 64 used colour attributes in a similar way, but a special multicolour mode, hardware sprites and hardware scrolling were used to avoid attribute clash. [13]

Sound output is through a beeper on the machine itself, capable of producing one channel with 10 octaves. Software was later available that could play two channel sound. The machine includes an expansion bus edge connector and 3.5 mm audio in/out ports for the connection of a cassette recorder for loading and saving programs and data. The "ear" port has a higher output than the "mic" and is recommended for headphones, with "mic" for attaching to other audio devices as line in. [14]

It was manufactured in Dundee, Scotland, in the now closed Timex factory. [15]


The machine's Sinclair BASIC interpreter is stored in ROM (along with fundamental system-routines) and was written by Steve Vickers on contract from Nine Tiles Ltd. The Spectrum's chiclet keyboard (on top of a membrane, similar to calculator keys) is marked with BASIC keywords. For example, pressing "G" when in programming mode would insert the BASIC command GO TO . [16]

The BASIC interpreter was developed from that used on the ZX81 and a ZX81 BASIC program can be typed into a Spectrum largely unmodified, but Spectrum BASIC included many extra features making it easier to use. The ZX Spectrum character set was expanded from that of the ZX81, which did not feature lower-case letters. Spectrum BASIC included extra keywords for the more advanced display and sound, and supported multi-statement lines. The cassette interface was much more advanced, saving and loading around five times faster than the ZX81 (1500 bits per second compared to 307), [17] and unlike the ZX81, the Spectrum could maintain the TV display during tape storage and retrieval operations. As well as being able to save programs, the Spectrum could save the contents of arrays, the contents of the screen memory, and the contents of any defined range of memory addresses.

Sinclair Research models

Pre-production designs

Rick Dickinson came up with a number of designs for the "ZX82" project before the final ZX Spectrum design. A number of the keyboard legends changed during the design phase including ARC becoming CIRCLE, FORE becoming INK and BACK becoming PAPER. [3] The Spectrum reused a number of design elements of the ZX81: The ROM code for things such as floating point calculations and expression parsing were very similar (with a few obsolete ZX81 routines left in the Spectrum ROM). The simple keyboard decoding and cassette interfaces were nearly identical (although the latter was now programmed to load/save at a higher speed). The central ULA integrated circuit was somewhat similar although it implemented the major enhancement over the ZX81: A (fully) hardware based television raster generator (with colour) that indirectly gave the new machine approximately four times as much processing power as the ZX81, simply due to the Z80 now being released from this video generation task. A bug in the ULA as originally designed meant that the keyboard did not always scan correctly, and was rectified by a "dead cockroach" (a small circuit board mounted upside down next to the CPU) for Issue 1 ZX Spectrums. [18]

ZX Spectrum 16K/48K

ZX Spectrum 16K/48K (Dimensions (mm): 233x144x30 (WxHxD) @ ~552 grams). ZXSpectrum48k.jpg
ZX Spectrum 16K/48K (Dimensions (mm): 233×144×30 (W×H×D) @ ~552 grams).

The original ZX Spectrum is remembered for its rubber keyboard, diminutive size and distinctive rainbow motif. It was originally released on 23 April 1982 [20] with 16 KB of RAM for £125 (equivalent to £348.92 in 2019) or with 48 KB for £175 (equivalent to £488.48 in 2019); [21] these prices were later reduced to £99 and £129 respectively. [22] Owners of the 16 KB model could purchase an internal 32 KB RAM upgrade, which for early "Issue 1" machines consisted of a daughterboard. Later issue machines required the fitting of 8 dynamic RAM chips and a few TTL chips. Users could mail their 16K Spectrums to Sinclair to be upgraded to 48 KB versions. Later revisions contained 64 KB of memory but were configured such that only 48 KB were usable. [23] External 32 KB RAM packs that mounted in the rear expansion slot were available from third parties. Both machines had 16 KB of onboard ROM.

An "Issue 1" ZX Spectrum can be distinguished from later models by the colour of the keys - light grey for Issue 1, blue-grey for later machines. [24] . According to the official service manual, approximately 26,000 of these original boards were manufactured. [25]

The Sinclair models featured audio line in and out, in the form of an "ear" and "mic" socket. An external tape recorder was needed to load the majority of software released, or the ZX Microdrive. Either socket could be connected to headphones or an amplifier as an audio output, although this would not disable the internal speaker.

ZX Spectrum+

ZX Spectrum+ (Dimensions (mm): 319x149x38 (WxHxD)) ZX Spectrum+.jpg
ZX Spectrum+ (Dimensions (mm): 319×149×38 (W×H×D))

Planning of the ZX Spectrum+ started in June 1984, [26] and it was released in October the same year. [27] This 48 KB Spectrum (development code-name TB [26] ) introduced a new QL-style case with an injection-moulded keyboard and a reset button that was basically a switch that shorted across the CPU reset capacitor. Electronically, it was identical to the previous 48 KB model. It was possible to change the system boards between the original case and the Spectrum+ case. It retailed for £179.95. [28] A DIY conversion-kit for older machines was available. Early on, the machine outsold the rubber-key model 2:1; [26] however, some retailers reported a failure rate of up to 30%, compared with a more usual 5–6% for the older model. [27]

ZX Spectrum 128

ZX Spectrum 128 ZX Spectrum128K.jpg
ZX Spectrum 128

In 1985, Sinclair developed the ZX Spectrum 128 (code-named Derby) in conjunction with their Spanish distributor Investrónica. [29] Investrónica had helped adapt the ZX Spectrum+ to the Spanish market after the Spanish government introduced a special tax on all computers with 64 KB RAM or less, [30] and a law which obliged all computers sold in Spain to support the Spanish alphabet and show messages in Spanish. [31]

The appearance of the ZX Spectrum 128 was similar to the ZX Spectrum+, with the exception of a large external heatsink for the internal 7805 voltage regulator added to the right hand end of the case, replacing the internal heatsink in previous versions. This external heatsink lead to the system's nickname, "The Toast Rack".

New features included 128 KB RAM with RAM disc commands 'save !"name"', three-channel audio via the AY-3-8912 chip, MIDI compatibility, an RS-232 serial port, an RGB monitor port, 32 KB of ROM including an improved BASIC editor, and an external keypad.

The machine was simultaneously presented for the first time and launched in September 1985 at the SIMO '85 trade show in Spain, with a price of 44,250 pesetas. Because of the large number of unsold Spectrum+ models, Sinclair decided not to start selling in the UK until January 1986 at a price of £179.95. [32] No external keypad was available for the UK release, although the ROM routines to use it and the port itself remained.

The Z80 processor used in the Spectrum has a 16-bit address bus, which means only 64 KB of memory can be directly addressed. To facilitate the extra 80 KB of RAM the designers used bank switching so the new memory would be available as eight pages of 16 KB at the top of the address space. The same technique was used to page between the new 16 KB editor ROM and the original 16 KB BASIC ROM at the bottom of the address space. [33]

The new sound chip and MIDI out abilities were exposed to the BASIC programming language with the command PLAY and a new command SPECTRUM was added to switch the machine into 48K mode, keeping the current BASIC program intact (although there is no way to switch back to 128K mode). To enable BASIC programmers to access the additional memory, a RAM disk was created where files could be stored in the additional 80 KB of RAM. The new commands took the place of two existing user-defined-character spaces causing compatibility problems with certain BASIC programs. [34]

The ZX Spectrum 128 had no internal speaker, unlike its predecessors. Sound was produced from the television speaker instead. [35]

The Spanish version had the "128K" logo in white; the British one had the same logo in red.

Amstrad models

ZX Spectrum +2

ZX Spectrum +2 ZX Spectrum Plus2.jpeg
ZX Spectrum +2

The ZX Spectrum +2 was Amstrad's first Spectrum, coming shortly after their purchase of the Spectrum range and "Sinclair" brand in 1986. The machine featured an all-new grey case featuring a spring-loaded keyboard, dual joystick ports, and a built-in cassette recorder dubbed the "Datacorder" (like the Amstrad CPC 464), but was in most respects identical to the ZX Spectrum 128. The main menu screen lacked the Spectrum 128's "Tape Test" option, and the ROM was altered to account for a new 1986 Amstrad copyright message. These changes resulted in minor incompatibility problems with software that accessed ROM routines at certain addresses. Production costs had been reduced and the retail price dropped to £139–£149. [36]

The new keyboard did not include the BASIC keyword markings that were found on earlier Spectrums, except for the keywords LOAD, CODE and RUN which were useful for loading software. This was not a major issue, as the +2 boasted a menu system, almost identical to the ZX Spectrum 128, where one could switch between 48K BASIC programming with the keywords, and 128K BASIC programming in which all words (keywords and otherwise) must be typed out in full (although the keywords are still stored internally as one character each). Despite these changes, the layout remained identical to that of the 128. [37]

The ZX Spectrum +2 power supply was a grey version of the ZX Spectrum+ and 128 power supply. [38]

ZX Spectrum +2A

ZX Spectrum +2A Spectrum 128-2.png
ZX Spectrum +2A

The ZX Spectrum +2A was a variant of the Spectrum +3, also released in 1987, and housed inside 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 a +2 style "datacorder" connected. [39] Originally, Amstrad planned to introduce an additional disk interface for the +2A/+2B called the AMSTRAD SI-1, [40] but it never appeared. If an external disk drive was added, the "+2A" on the system OS menu would change to a +3.

The power supply of the ZX Spectrum +2A used the same pinout as the +3. The power supply purchased with the +2A/B had "Sinclair +2" written on the case. [41]

ZX Spectrum +3

ZX Spectrum +3 ZX Spectrum Plus3.jpeg
ZX Spectrum +3

The ZX Spectrum +3, released in 1987, looked similar to the +2A but featured a built-in 3-inch floppy disk drive (like the Amstrad CPC 6128) instead of the tape drive, and was in a black case. It was launched in 1987, initially retailed for £249 [42] and then later £199 [43] and was the only Spectrum capable of running the CP/M operating system without additional hardware.

The +3 saw the addition of two more 16 KB ROMs. One was home to the second part of the reorganised 128 ROM and the other hosted the +3's disk operating system. This was a modified version of Amstrad's PCWDOS (the disk access code used in LocoScript), called +3DOS. These two new 16 KB ROMs and the original two 16 KB ROMs were now physically implemented together as two 32 KB chips. To be able to run CP/M, which requires RAM at the bottom of the address space, the bank-switching was further improved, allowing the ROM to be paged out for another 16 KB of RAM.

Such core changes brought incompatibilities:

Some older 48K and 128K games were incompatible with the machine. The ZX Interface 1 was incompatible due to differences in ROM and expansion connector, making it impossible to connect and use the Microdrive units. [44]

There was a regression in sound quality from the previous 128K models – an error with a resistor placement meant sound was distorted. [45]

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 be used with the +2A/B. The power supply purchased with the +3 had "Sinclair +3" written on the case. [46]

Production of the +3 ceased in December 1990, believed to be in response for Amstrad relaunching their CPC range [47] . 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. [48]

ZX Spectrum +2B and +3B

The ZX Spectrum +2B and ZX Spectrum +3B were functionally similar in design to the Spectrum +2A and +3. [49] The main electronic differences being changes to the generation of the audio output signal to resolve problems with clipping.

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.


Official clones

Didaktik M Didaktik M, ZX Spectrum clone.jpg
Didaktik M

Sinclair licensed the Spectrum design to Timex Corporation in the United States. An enhanced version with better sound, graphics and other modifications was marketed in the USA by Timex as the Timex Sinclair 2068. Timex's derivatives were largely incompatible with Sinclair systems. Some of the Timex innovations were later adopted by Sinclair Research. A case in point was the abortive Pandora portable Spectrum, whose ULA had the high resolution video mode pioneered in the TS2068. Pandora had a flat-screen monitor and Microdrives and was intended to be Sinclair's business portable. After Amstrad bought the computer business of Sinclair Research, Sir Clive retained the rights to the Pandora project, and it evolved into the Cambridge Computer Z88, launched in 1987. [50]

Starting in 1984, Timex of Portugal developed and produced several Timex branded computers, including the Timex Computer 2048, highly compatible with the Sinclair ZX Spectrum 48K, which was very successful in both Portugal and Poland. [51] An NTSC version was also made, initially intended for a United States release, but it was sold only in Chile and Argentina. Timex of Portugal also made a PAL version of the TS2068, called the Timex Computer 2068 (or TC2068 for short) which had different buffers for both the ULA and the CPU, which significantly increased the compatibility with ZX Spectrum software when compared to the North American model (the TS2068). The expansion port was also modified and made to be 100% compatible with the ZX Spectrum's, which bypassed the need for a "Twister Board" expansion that the TS2068 needed in order to make it compatible with ZX Spectrum expansion hardware. It also had the AY sound output routed to the monitor/TV speakers instead of the internal twitter. The software developed for the TC2068 is completely compatible with the TS2068, since the ROMs weren't altered. Timex of Portugal also developed a ZX Spectrum "emulator" on cartridge form that mapped the first 16 KB exactly like the earlier TC2048 computer did. Several other upgrades were made available, including a BASIC64 cartridge that enabled the TC2068 to use high resolution (512x192) modes. Despite having an AY-3-8912 sound chip, it's not connected in the same ports as in the ZX Spectrum 128K, rendering the TC2084 incompatible with the AY sound that the Spectrum 128K games produced. Due to all its advantages compared to the usual TS2068, a North American company, Zebra Systems, licensed the Timex TC2068 and sold it in the United States as the Zebra Silver Avenger. They also sold the FDD 3000 as the Zebra FDD 3000 in a silver case (as opposed to the European black cases) to match their colour scheme. Timex of Portugal was working on a successor to the TC2068 called the TC3256, using a Z80A CPU and featuring 256 KB of RAM, which would feature a ZX Spectrum BASIC operating mode and a CP/M operating mode, but the company pulled the plug on its development as the 8-bit market was no longer profitable by the end of 1989. Only one complete and fully working prototype of the TC3256 was made. [52]

In India, Decibells Electronics introduced a licensed version of the Spectrum+ in 1986. Dubbed the "db Spectrum+", it did reasonably well in the Indian market and sold many units until 1990, when the market died away. [53]

In 2013, an FPGA-based redesign of the original ZX Spectrum known as the ZX-Uno, was formally announced. It went into crowdfunding in 2016 and the first boards went on sale during the same year. [54]

The ZX Spectrum Vega, released in 2015, and its unreleased follow-up, the ZX Spectrum Vega+ are modern redesigns of the ZX Spectrum in the form of a handheld TV game and a handheld game console respectively. [55] [56]

More recently, in April 2017, the ZX Spectrum Next was announced and a Kickstarter campaign launched. It's a full computer-form redesign of the ZX Spectrum computer, using FPGA technology and significantly expanding the original hardware abilities while still maintaining compatibility. The final computer was scheduled to be delivered to Kickstarter backers in 2018. The board-only computer ('Just the Board' tier) was delivered to backers in late 2017 [57] . However, the full computer since missed multiple revised release dates. As of July 2019, it has still not been shipped due to problems with the keyboard design. [58]

HC85 HC 85 - 01.JPG

Unofficial clones

Numerous unofficial Spectrum clones were produced, especially in the Eastern and Middle European countries (e.g. in USSR, Romania, and Czechoslovakia) where several models were produced (such as the Tim-S, HC85, HC91, Cobra, Junior, CIP, CIP 3, Jet, Didaktik M), some featuring CP/M and a 5.25"/3.5" floppy disk. There were also clones produced in South America (e.g. Microdigital TK90X and TK95, made in Brazil). In the Soviet Union, ZX Spectrum clones were assembled by thousands of small start-ups and distributed through poster ads and street stalls. Over 50 such clone models existed. [59] Some of them are still being produced, such as the Pentagon and ATM Turbo .

In the UK, Spectrum peripheral vendor Miles Gordon Technology (MGT) released the SAM Coupé as a potential successor with some Spectrum compatibility. By this point, the Commodore Amiga and Atari ST had taken hold of the market, leaving MGT in eventual receivership. [60]


Several peripherals were marketed by Sinclair: the ZX Printer was already on the market, [61] as the ZX Spectrum expansion bus was partially backwards-compatible with that of the ZX81.

The ZX Interface 1 add-on module included 8 KB of ROM, an RS-232 serial port, a proprietary LAN interface (called ZX Net), and an interface for the connection of up to eight ZX Microdrives  – somewhat unreliable but speedy tape-loop cartridge storage devices released in July 1983. [62] [63] These were 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 ZX Interface 2 which added two joystick ports and a ROM cartridge port. [64]

There were a plethora of third-party hardware addons. The better known of these included the Kempston joystick interface, the Morex Peripherals Centronics/RS-232 interface, the Currah Microspeech unit (speech synthesis), [65] Videoface Digitiser, [66] RAM pack, the Cheetah Marketing SpecDrum, [67] a drum machine, and the Multiface, [68] a snapshot and disassembly tool from Romantic Robot. Keyboards were especially popular in view of the original's notorious "dead flesh" feel. [69]

There were disk drive interfaces, such as the Abbeydale Designers/Watford Electronics SPDOS, Abbeydale Designers/Kempston KDOS and Opus Discovery. The SPDOS and KDOS interfaces were the first to come bundled with office productivity software (Tasword Word Processor, Masterfile database and Omnicalc spreadsheet). This bundle, together with OCP's Stock Control, Finance and Payroll systems, introduced small businesses to a streamlined, computerised operation. The most popular floppy disk systems (except in East Europe) were the DISCiPLE and +D systems released by Miles Gordon Technology in 1987 and 1988 respectively. Both systems had the ability to store memory images onto disk snapshots could later be used to restore the Spectrum to its exact previous state. They were both compatible with the Microdrive command syntax, which made porting existing software much simpler. [70]

During the mid-1980s, Telemap Group Ltd launched a fee-based service allowing users to connect their ZX Spectrums via a Prism Micro Products VTX5000 modem to a viewdata service known as Micronet 800, hosted by Prestel, which provided news and information about microcomputers. The service allowed a form of instant messaging and online shopping. [71]

Currently, many third party peripherals are still being produced, like the SMART Card Reader or the DivMMC Enjoy that allow original 48K and 128K ZX Spectrums to read SD Cards bypassing the need to use cassette tapes; the Dandanator! mini, an EEPROM reader that allows loading memory snapshots directly onto the ZX Spectrum; AY expansion boards for the 48K, Joystick boards and adaptors, etc. Some ZX Spectrum-compatible joysticks are still being manufactured and other replacement parts—like keyboard membranes, multicoloured cases and faceplates—are also being produced.


ZX Rebelstar 3.png
Towdie Screenshot.png
ZX Laser Squad.png
Sample screenshots from ZX Spectrum games

While games comprised the majority of commercial ZX Spectrum software, there were also programming language implementations, databases (e.g. VU-File [72] ), word processors (e.g. Tasword  II [73] ), spreadsheets (e.g. VU-Calc [72] ), drawing and painting tools (e.g. OCP Art Studio [74] ), and even 3D-modelling (e.g. VU-3D [75] [76] ) and archaeology software [77] amongst many other types.

The early Spectrum models' great success as a games platform came in spite of its lack of built-in joystick ports, primitive sound generation, and colour support that was optimised for text display: [78] the hardware limitations of the platform required a particular level of creativity from video game designers. [79]

The ZX Spectrum came bundled with a software starter pack in the form of a cassette tape entitled Horizons: Software Starter Pack, [80] which included 8 programs  Thro' the Wall (a Breakout clone), Bubblesort, Evolution (an ecosystem of foxes and rabbits), Life (an implementation of Conway's Game of Life), Draw (a basic object-based drawing utility), Monte Carlo (a simulation of the rolling of two dice), Character Generator (for editing user defined graphics), Beating of Waves (plots the sum of two sine waves).

According to the 90th issue of the British gaming magazine GamesMaster, the ten biggest games released were (in descending order) Head Over Heels, Jet Set Willy, Skool Daze, Renegade, R-Type, Knight Lore, Dizzy, The Hobbit, The Way of the Exploding Fist, and Match Day II. [81]

The last full price, commercial game be released for the Spectrum was Alternative Software's Dalek Attack, which was released in July 1993.[ citation needed ]


Most Spectrum software was originally distributed on audio cassette tapes. The Spectrum was intended to work with a normal domestic cassette recorder, [82] and despite differences in audio reproduction fidelity, the software loading process was quite reliable and faster than on competing systems of the time[ citation needed ].

Although the ZX Microdrive was initially greeted with good reviews, [83] it never took off as a distribution method due to worries about the quality of the cartridges and piracy. [84] Hence the main use became to complement tape releases, usually utilities and niche products like the Tasword word processing software and Trans Express, (a tape to microdrive copying utility). No games are known to be exclusively released on Microdrive.

Although the Interface 2 proved popular, the high cost of ROM cartridges, and the fact that they were limited to 16K in size, meant that very few titles were released in this format. [85]

Software was distributed through print media; magazines [86] and books. [87] The reader would type the BASIC program listing into the computer by hand, run it, and could save it to tape for later use. Software distributed in this way was in general simpler and slower than its assembly language counterparts. Magazines printed long lists of checksummed hexadecimal digits with machine code games or tools.

Another software distribution method was to broadcast the audio stream from the cassette on another medium and have users record it onto an audio cassette themselves. In radio or television shows in many European countries, the host would describe a program, instruct the audience to connect a cassette tape recorder to the radio or TV and then broadcast the program over the airwaves in audio format. [88] Some magazines distributed 7" 33⅓ rpm flexidisc records, a variant of regular vinyl records which could be played on a standard record player. [89] These disks were known under various trademarked names including "Floppy ROM", "Flexisoft", and "Discoflex".

Copying and backup

Spectrum software was distributed on audio cassettes Psion Horizons for ZX Spectrum cassette.jpg
Spectrum software was distributed on audio cassettes

Many copiers—utilities to copy programs from audio tape to another tape, microdrive tapes, and later on diskettes—were available for the Spectrum. As a response to this, publishers introduced copy protection measures to their software, including different loading schemes. [90] Other methods for copy prevention were also used including asking for a particular word from the documentation included with the game—often a novella such as the Silicon Dreams trilogy—or another physical device distributed with the software—e.g. Lenslok as used in Elite, or the colour-code chart included with Jet Set Willy. Special hardware, such as Romantic Robot's Multiface, was able to dump a copy of the ZX Spectrum RAM to disk/tape at the press of a button, entirely circumventing the copy protection systems.

Most Spectrum software has been converted to current media and is available for download. One popular program for converting Spectrum files from tape is Taper; it allows connecting a cassette tape player to the line in port of a sound card, or—through a simple home-built device—to the parallel port of a PC. [91] Once in files on a host machine, the software can be executed on an emulator.


The ZX Spectrum enjoyed a very strong community early on. Several dedicated magazines were released including Sinclair User (1982), Your Spectrum (1983), rebranded as Your Sinclair in 1986, and CRASH (1984). Early on they were very technically oriented with type-in programs and machine code tutorials. Later on they became almost completely game-oriented. Several general contemporary computer magazines covered the ZX Spectrum in more or less detail. They included Computer Gamer , Computer and Video Games , Computing Today , Popular Computing Weekly , Your Computer and The Games Machine . [92]

The Spectrum is affectionately known as the Speccy by elements of its fan following. [93]

More than 80 electronic magazines existed, many in Russian. Most notable of them were AlchNews (UK), ZX-Format (Russia), Adventurer (Russia) and Spectrofon (Russia).

Notable developers

A number of notable games developers began their careers on the ZX Spectrum, including David Perry of Shiny Entertainment, and Tim and Chris Stamper (founders of Rare, formerly Ultimate Play the Game, maker of many games for Nintendo and Microsoft game consoles). Other prominent games developers include Julian Gollop ( Chaos , Rebelstar , X-COM series), Matthew Smith ( Manic Miner , Jet Set Willy ), Jon Ritman ( Match Day , Head Over Heels ), Jonathan "Joffa" Smith (Ping Pong, Batman: The Caped Crusader , Mikie , Hyper Sports ), The Oliver Twins (the Dizzy series), Clive Townsend ( Saboteur ), Sandy White ( Ant Attack ; I, of the Mask), Pete Cooke ( Tau Ceti ), Mike Singleton ( The Lords of Midnight , War In Middle Earth ), and Alan Cox. [94] Although the 48K Spectrum's audio hardware was not as capable as chips in other popular 8-bit home computers of the era, computer musicians David Whittaker and Tim Follin produced notable multi-channel music for it.

Jeff Minter ported some of his Commodore VIC-20 games to the ZX Spectrum. [95]


BYTE in January 1983 acknowledged the appeal of the Spectrum's low £125 price to British consumers and called it a "promising machine". It criticised the keyboard; "inexpensive or not, the ... layout is impossible to justify ... poorly designed in several respects". The review was skeptical of the computer's appeal to American consumers if sold for US$220—"hardly competitive with comparable low-cost American units"—and expected that Timex would sell it for $125–150. [96]


On 23 April 2012, a Google doodle honoured the 30th anniversary of the Spectrum. As it coincided with St George's Day, the logo was of St George fighting a dragon in the style of a Spectrum loading screen. [97]

In January 2014, Elite Systems, who produced a successful range of software for the original ZX Spectrum in the 1980s, announced plans for a Spectrum-themed bluetooth keyboard that would attach to mobile devices such as the iPad. [98] [99] The company provided a crowdfunding campaign in order to fund the project, which would be compatible with games already released on iTunes and Google Play. [100] Elite Systems took down its Spectrum Collection application the following month, due to complaints from authors of the original 1980s game software that they had not been paid for the content. [101]

Later that year, a £100 Sinclair ZX Spectrum Vega retro video game console was announced by Retro Computers and crowdfunded on IndieGogo, with the apparent backing of Clive Sinclair as an investor, [102] but without a full keyboard and manufactured in a limited capacity. [103]

In December 2018, one of the alternate endings in Black Mirror: Bandersnatch included the main character playing data tape audio that, when loaded into a ZX Spectrum software emulator, generates a QR code leading to a website with a playable version of the Nohzdyve game featured in the episode. [104]

Some programmers have continued to code for the platform by using emulators on PCs. [105]

See also

Related Research Articles

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