ZX Spectrum


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    /wiki/ZX Spectrumwork
    A 48k ZX Spectrum. Photo by Bill Bertram used under CC BY-SA 2.5 terms.

    Britain's equivalent to the Apple II and Commodore 64.

    And the polar opposite of the X68000 as well (in hardware specs).

    The Sinclair ZX Spectrum (pronounced as "zed-ecks" per British English convention, not "zee-ecks"), or "Speccy" to its fans, is a masterpiece of early 1980s computing Minimalism. Everything is as simple and cheap as possible. Because of this, it became famous in Britain and Spain in the 1980s as a game-friendly home computer for people who otherwise couldn't afford one. The Speccy's relative simplicity led to it being widely cloned especially in Eastern Europe and the former Soviet Union where workalikes such as the Pentagon became popular.

    History

    The Speccy is based on a couple of earlier computers, the ZX80 and ZX81. These were little more than a Z80 processor, an incomplete 4K version of BASIC, 1K of RAM, and a membrane keyboard — the first releases were sold as kits. The Z80 drew the text-only screen (when it wasn't busy), video output was to a TV set, and programs were stored on audio cassettes. The primitiveness was deliberate — the ZX80 was designed to be the cheapest computer on the market, and the ZX81 made the original design even cheaper. The ZX81 was only £70 (or $100) in 1981, and sold over a million units. The Speccy, designed to be the cheapest color computer on the market, improved on the ZX81 with a 16K almost-complete BASIC, 16K or 48K of RAM, a video chip, a beeper, and a rubber keyboard.

    The Speccy was released in April 1982 at £125 for the 16K model and £175 for 48K, dropping as time went on. Sinclair was swamped with orders. It held its own against the Commodore 64, and British competitors such as the BBC Micro and Amstrad CPC. Sales figures went into the millions, mostly of the 48K model, and it brought Britain into the home computer age (and earned its inventor, Clive Sinclair, a knighthood.[1])

    The Spectrum+, introduced in 1984, replaced the rubber keyboard with a plastic one, modeled after the failed Sinclair QL (an abortive attempt to create a business machine to compete with the IBM PC), and fixed some graphics bugs. The third and final Sinclair Spectrum was the 128, in 1986. This had 128K of RAM, an even better BASIC, MIDI, a monitor port, and three-channel sound.

    Amstrad bought Sinclair in 1986 and continued improving the Speccy with a full-travel keyboard, an internal cassette drive, and finally with a disk drive in 1987. But these later models have backward-compatibility problems.

    Play it Again, Sam

    Speaking of backward-compatibility problems, the SAM Coupé was released in 1989 as a next-generation Speccy. Inspired by a terminated project at Sinclair Research and designed by former Sinclair employees at Miles Gordon Technology (MGT), the SAM had better specs than any Spectrum - but without the intellectual property that now belonged to Amstrad there was a limit to how compatible MGT could make it.

    The SAM could be made to run most 48K software with a bit of hacking, and its games got regular slots in the big Spectrum magazines. However, despite having as much RAM as an Amiga 1000, it was still an 8-bit machine in an increasingly 16-bit market, and never made it commercially.

    Clones & Emulators

    The demise of the Speccy in the early 1990s isn't the end of the story. Because it's so simple, it's easy to clone. The first Speccy clone was an authorized version by Timex[2] for the United States, Portugal and Poland. Unauthorized Speccy clones started appearing in the Soviet Union in the mid-1980s, followed by several countries in eastern Europe, along with India, Brazil and Argentina.

    Then came the retro scene: Of the numerous Speccy clones listed on The Other Wiki, at least half a dozen were released in the '10s or '20s. [3]

    The fansite World of Spectrum, which is officially endorsed by Amstrad, offers various emulators for the system and most of the original games for free as memory dumps or tape images.[4] The site has gone all out to ask the original producers of the games for permission to distribute them freely (permission which has been granted in many cases, but a lot of the rights have been inherited by large companies that flatly refuse to respond to any requests. Then there are a few that respond with a no, presumably fearing that allowing free download of something that ceased to be profitable to them in 1993 will compromise their current catalogues). The site has about 90% of the computer's software library up for free download.

    Specifications

     

    • Zilog Z80A CPU, 3.5 Mhz.
    • Semi-custom graphics chip (off-the-shelf logic array with custom functionality).
    • Spectrum 128 and Amstrad models: General Instruments AY-3-8912 sound chip.

    Not very expandable, except kits were sold to convert the 16K model to 48K.

    • Spectrum: 16K or 48K.
    • Spectrum+: 48K.
    • Spectrum 128 and Amstrad models: 128K.
    • The OS is stored in ROM - 16K for the 16 or 48K Spectrum, more for later models. Some add-ons could swap in some RAM in its place.

    Output is to a TV set via a built-in UHF modulator. A composite signal is also available from the edge connector.

    • 256x192 resolution.
    • 8-color palette, with two brightnesses per color. Good luck spotting the difference between the two brightnesses of black.
    • Two colors per 8x8 pixel block (both had to be the same brightness, as the Speccy's display was famously idiosyncratic — each pixel block was represented as 3 bits of foreground color, 3 bits of background colour, 1 bit for brightness, and 1 bit for flashing...a total of 8 bits, or 1 byte).
    • The display area is surrounded by a border that can be any one of the 8 non-bright colours. Carefully-timed machine code routines can make horizontal lines appear in the border - this is done by the built-in tape loading routines[5] and a few games and demos.

    Examples can be found on the music subpage.

    • Spectrum and Spectrum+: Beeper, controlled by toggling a single output bit to make it vibrate. Can cover 10 octaves but takes CPU time.
    • Spectrum 128 and Amstrad models: Three channels, square or noise waveforms, 10 octaves, programmable ADSR, 8-bit sample playback.

    Connectors were kept to a minimum to control costs and speed up the initial launch. Other ports became available via add-ons.

    • 3.5mm "Mic" and "Ear" jacks (actually line-out and line-in respectively, as they were meant to be plugged in to the same-named ports on a cassette recorder).
    • 9V DC in.
    • TV out (coaxial providing an analogue UHF signal).
    • Edge Connector/expansion bus - literally the edge of the motherboard, sporting a double row of printed tabs. Exposes enough functionality to "do almost anything with a Spectrum that you can with a Z80."[6]

    Software

    Thousands upon thousands of games, plus the occasional educational or productivity title. As of 2025, around 11,000 games are listed in the World Of Spectrum library,[7] and that's likely to have missed countless thousands of homebrews, magazine typeins, and others.

    The infamous colour system meant a lot of games on this rainbow-badged computer were rendered in monochrome to prevent "colour clash". This is especially true of 3D games, but a lot of cross-platform titles became monochrome on the Speccy just to make the conversion easier (and cheaper).[8] Some games, like Trantor, are remembered for bucking this trend with big, colourful animation, though the game still bore hallmarks of the Speccy's colour limitations. A number of developers came up with tricks to sidestep the colour clash issue, such as with the late Don Priestley whose games were built around a distinct art style to cleverly fit within the system's confines, starting with Popeye, whose licensor insisted on the titular sailor looking as close to the source material as possible (despite knowing absolutely nothing about the limitations of computer hardware at the time),[9] leading to Priestley to come up with the workaround. Priestley's rendition of the spinach-munching sailor turned up to be far larger than the characters commonly found in video games of the day, taking up roughly half of the screen's vertical resolution. Yet somehow he was able to get the damn character to work, though the resulting graphical technique he devised slowed down the game considerably and made it more appropriate for slower-paced titles such as those marketed towards children.

    On the plus side, the shortage of video optimisations gave developers a clean graphical slate, leading to a plethora of different visual styles. Isometric Projection became something of a staple, to the annoyance of joystick owners,[10] and there are some impressive first-person 3D titles. At least one isometric game, Amaurote, was switched to a top-down view on the C64, presumably to make use of the latter's hardware sprites.

    Titles And Series That Started Here

    Action Adventure

    Adventure Game

    • Skool Daze
      • Back To Skool

    Fighting Game

    • International Karate
      • IK+ (released cross-platform), successor to the above.
    Call it a sequel and you'll land up flat on your back
    —Inlay card

    First-Person Shooter

    • Tau Ceti
      • Academy, the sequel, released cross-platform.

    Interactive Fiction

    Maze Game

    • Gyron (originally released in two parts, Gyron Atrium and Gyron necropolis.)
      • Gyron Arena
    • Hungry Horace

    Platform Game

    • Manic Miner - which was the first game to include in-game music and sound effects using only the beeper, a feat many had considered impossible.
      • Jet Set Willy
        • Jet Set Willy 2 started life as the Amstrad CPC port of Jet Set Willy. The map was so much bigger they decided to port it back to the Speccy as a sequel.
    • Horace and the Spiders, the third game in the Horace series and the first not converted to other platforms.
      • Horace in the Mystic Woods, an unofficial conversion from the Psion 3-series.

    Simulation Game

    • Flight Simulation (1982, Psion; actually started on the ZX81)
    • Dark Star (1984, Design Design)
    • Just Imagine (1986, Central Solutions)

    Strategy Game

    • Some RTS which most certainly isn't Stonkers.[11]
    • Just about anything by Julian Gollop (most of his early work was on the Speccy).
      • Rebelstar Raiders
        • Rebelstar
        • Rebelstar 2
      • Chaos: The Battle of Wizards
        • Lords of Chaos, released cross-platform.
      • Laser Squad

    Third-Person Shooter

    Non-games

    • Tasword, a 64-column word processor (actually started on the ZX81).
    • Psion's productivity suite
      • VU-Calc, a spreadsheet
      • VU-File, a database
      • VU-3D, a 3D rendering program
      • They also released Make-A-Chip, an educational program about logic gates.
    • Wham! The Music Box: Music generator endorsed by a big English band of the '80s.
    • Numerous compilers and assemblers, including
      • Hisoft's BASIC and Pascal
      • Zeus assembler

    Ports, Conversions & Multiplatformers

    Games marked with a * were initially (or solely) released on both the Speccy and Amstrad CPC, which had the same processor.

    Action Adventure

    Adventure Game

    • Most of the Dizzy series.*
    • Cylu
    • All of the Wally Week series except Automania (below).
      • Pyjamarama
      • Everyone's a Wally
      • Herbert's Dummy Run
      • Three Weeks in Paradise
    • Sweevo's World*
      • Sweevo's Whirled, an extended 128K version of the same game.
      • Hydrofool*, the only sequel.
    • Rasterscan
    • Rygar

    Beat'Em Up

    Fighting Game

    First-Person Shooter

    Hack and Slash

    Interactive Fiction

    Maze Game

    Platform Game

    Puzzle Game

    Racing Game

    Strategy Game

    Third-Person Shooter

    Wide Open Sandbox

    Add-ons

    Sinclair released several add-ons to extend the Spectrum's functionality, and numerous other companies got in on the action. The ZX printer, already released for use with the ZX81, could plug straight in, and the burgeoning games market allowed several competing joystick adaptors to thrive.

    All Spectrum add-ons are plugged in to the "edge connector" or "expansion bus". Some devices include a duplicated edge connector for daisy-chaining, and for the rest, "expansion doublers" could be bought.

    Attachments included:

    Hacker/debugging tools

    • Various external ROMs, including one in...
    • Romantic Robot's "Multiface". Allowed any running program to be frozen and inspected, using its own buffer memory to run user code. Magazines frequently published "Multiface cheats", which were mostly memory addresses to be zeroed to get infinite lives in various games.

    Joystick interfaces

    All the common joystick interfaces supported the same joysticks - the simple digital ones that were used on several home micros in the 80s.[12] Some of the earlier interfaces also included ROM cartridge slots, but the cartridges never caught on.

    • ZX Interface 2 - The official one, sporting two joystick ports and the original ROM cartridge connector. The joystick part was built in to the Spectrum +2. Joystick movements simulate number key presses (1-5 for the left stick, 6-0 for the right) to make life easier for game developers.
    • Kempston - the most popular, launched before the Interface 2.
    • Cursor - which emulates arrow key presses instead of number keys.[13]
    • Protek.
    • Fuller.
    • RAM Turbo - one of several attempts to combine multiple joystick protocols in one unit. At least two of the protocols worked, and it had a reset button - a feature that was missing from rubber-key Spectrums.

    Printers

    • ZX Printer - Sinclair's spark-gap printer, printing on 100mm-wide rolls of aluminium-coated paper.
    • At least one electrically-compatible clone of the ZX printer was spotted in the wild, printing on larger, more ordinary-looking thermal paper.
    • Other printers could be attached via the Interface 1.

    Others

    • ZX Interface 1 - released by Sinclair shortly after the first Spectrum. Provides an RS232 port and connectors for Microdrives[14] and a proprietary network.
    • Several mice and floppy drive controllers, including...
      • MGT's Disciple: a floppy drive controller that, unlike the Spectrum +3, used common disk sizes. Included a printer port and the ability to snapshot the Speccy's state.
      • +D, a cheaper successor to Disciple.
    • Fuller Orator, a sound box using the AY-3-8912 (the same sound chip that was built into later Spectrums).
    • Mikro-Plus: Puts 16K external RAM in place of the ROM, so it would also count as a hacker tool - but this was marketed by games publisher Mikro-Gen to allow bigger games to be loaded.


    1. ↑ {well, except for the little fact that Uncle Clive had nothing to do with the design of any of his company computer products; Speccy hardware was designed by Sinclair Research's Richard Altwasser, and Steve Vickers of the Nine Tiles wrote the system software, including Basic 48}
    2. ↑ Yes, the wristwatch company - they also did Sinclair's UK manufacturing
    3. ↑ Amstrad have helped by announcing that the Spectrum's OS can be distributed freely, making it easier to produce faithful, legal clones and emulators in the West.
    4. ↑ (If you don't want to get flamed by the Spectrum community, never refer to any Spectrum game as a "ROM"...unless you're referring to an Interface 2 cartridge, of which only a handful were released. Arcade and console game images are called "ROMs" because that's literally what they are; Speccy games, on the other hand, were almost exclusively released on tape or disk.)
    5. ↑ An experienced user can tell how good the tone is on their tape player by watching the border
    6. ↑ according to the original Spectrum BASIC manual
    7. ↑ The unofficial World of Spectrum Classic has almost 17,000.
    8. ↑ Conversely, some games kept their Speccy-friendly looks when they were cheaply ported to more colour-capable machines - as the CPC guys can attest.
    9. ↑ Which is a Riddle for the Ages as the Atari 2600 conversion of Nintendo's Popeye arcade game had Popeye, Olive and Bluto look more pixelated than King Features Syndicate would have liked.
    10. ↑ Moving diagonally with any common Spectrum joystick meant activating two microswitches at once, which was just awkward enough to be irritating when all the game's directions are diagonal. Some games got round this by rotating the cardinal directions by 45°, which didn't feel a whole lot better.
    11. ↑ follow the link for this in-joke if you don't get it.
    12. ↑ They used the same plug as the 9-pin RS232, but a different protocol.
    13. ↑ Although the arrow keys are technically shifted number keys
    14. ↑ A midget data tape produced by Sinclair
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