   #copyright

ZX Spectrum

2007 Schools Wikipedia Selection. Related subjects: Computing hardware and
infrastructure

       The original 1982 ZX Spectrum.
                 ZX Spectrum
   Type         Home computer
   Released     April 1982
   Discontinued December 1990
   Processor    Z80 @ 3.5 MHz and equivalent
   Memory       16 kB / 48 kB / 128 kB
   OS           Sinclair BASIC

   The ZX Spectrum is a home computer released in the United Kingdom in
   1982 by Sinclair Research Ltd. Originally dubbed the ZX82, the machine
   was later renamed the ZX Spectrum by Sinclair to highlight the
   machine's colour display, compared to the black-and-white of its
   predecessor, the Sinclair ZX81.

   The Spectrum was the first mainstream audience home computer in the UK,
   similar in significance to the Commodore 64 in the USA; the C64 was the
   main rival to the Spectrum in the UK market during the early 1980s.

   In 1980–82 the UK Department of Education and Science had begun the
   Microelectronics Education Programme to introduce microprocessing
   concepts and educational materials. In 1982 through to 1986, the
   Department of Industry (DoI) allocated funding to assist UK local
   education authorities to supply their schools with a range of
   computers, with the ZX Spectrum proving useful for the control
   projects.

Hardware

   ZX Spectrum 48K motherboard (Issue 3B — 1983)
   Enlarge
   ZX Spectrum 48K motherboard (Issue 3B — 1983)

   The Spectrum's hardware was designed by Richard Altwasser of Sinclair
   Research. Sinclair's industrial designer Rick Dickinson was responsible
   for the machine's outward appearance.

   Based on a Zilog Z80A CPU running at 3.5  MHz, the original Spectrum
   came with either 16  kB or 48 kB of RAM. Both units had 16 kB of ROM.

   The Spectrum's video output was through an RF modulator and was
   designed for use with contemporary portable television sets, for a
   simple colour graphic display. Text could be displayed using 32 columns
   × 24 rows of characters from the ZX 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 image 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, both of
   which had to be either bright or non-bright. This led to what was
   called colour clash or attribute clash with some bizarre effects in
   arcade style games. This problem became a distinctive feature of the
   Spectrum and an in-joke among Spectrum users, as well as a point of
   derision by advocates of other systems. Other machines available around
   the same time, for example the Amstrad CPC, did not suffer from this
   problem. The Commodore 64 used colour attributes, but hardware sprites
   and scrolling were used to avoid attribute clash.

   Sound output was through a beeper on the machine itself. This was
   capable of producing one channel with 10 octaves over ten semitones.
   The machine also included an expansion bus edge connector and audio
   in/out ports for the connection of a cassette recorder for loading and
   saving programs and data.

   The machine's software was written by Steve Vickers on contract from
   Nine Tiles Ltd, the authors of Sinclair BASIC. The Spectrum's chiclet
   keyboard (on top of a membrane, similar to calculator keys) was marked
   with Sinclair BASIC keywords, so that, for example, pressing "G" when
   in programming mode would insert the BASIC command GO TO.

Models

Sinclair Research models

   The original ZX Spectrum is remembered for its rubber keyboard and
   diminutive size. It was originally released in 1982 with 16 kB of RAM
   for GB£125 or with 48 kB for £175; these prices were later reduced to
   £99 and £129 respectively. Owners of the 16 kB model could purchase an
   internal 32 kB RAM upgrade daughterboard, which consists 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. To reduce the price, the 32
   kB extension actually comprised eight faulty 64  kilobit chips with
   only one half of their capacity working and/or available. External 32
   kB RAMpacks that mounted in the rear expansion slot were also available
   from third parties. As with the ZX81, "RAMpack wobble" caused by poor
   connection with the expansion was a frequent problem for many users,
   causing instant crashes and sometimes ULA or CPU burnout. Both machines
   had 16kB of onboard ROM.
   ZX Spectrum+
   Enlarge
   ZX Spectrum+

   Planning of the ZX Spectrum+ started in June 1984, and was released in
   October the same year. This 48 kB Spectrum (development code-name TB)
   introduced a new QL-style enclosure with a much needed
   injection-moulded keyboard and a reset button, retailing for £179.95. A
   DIY conversion-kit for older machines was also available. Early on, the
   machine outsold the rubber-key model 2:1; however, some retailers
   reported very high failure rates.
   ZX Spectrum 128
   Enlarge
   ZX Spectrum 128

   Sinclair developed the ZX Spectrum 128 (code-named Derby) in
   conjunction with their Spanish distributor Investrónica. 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 which did not support the Spanish alphabet (including ñ)
   and show messages in Spanish.

   New features included 128 kB RAM, 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 (€266). Because of the large amount of unsold
   Spectrum+ models, Sinclair decided not to start selling in the UK until
   January 1986 at a price of £179.95. No external keypad was available
   for the UK release, although the ROM routines to utilise it and the
   port itself, which was hastily renamed "AUX", remained.

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

   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. 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 issues with some BASIC programs.

   The Spanish version had the "128K" logo (right, bottom of the computer)
   in white colour while the English one had the same logo in red colour.

Amstrad models

   ZX Spectrum +2
   Enlarge
   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 enclosure 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 all
   user-visible respects) otherwise identical to the ZX Spectrum 128.
   Production costs had been reduced and the retail price dropped to
   £139–£149.

   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. However, the layout remained
   identical to that of the 128.
   ZX Spectrum +3
   Enlarge
   ZX Spectrum +3

   The ZX Spectrum +3 looked similar to the +2 but featured a built-in
   3-inch floppy disk drive (like the Amstrad CPC 6128) instead of the
   tape drive. It was launched in 1987, initially retailed for £249 and
   then later £199 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, now physically
   implemented as two 32 kB chips. 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 AMSDOS, called +3DOS.
   To facilitate the new ROMs and CP/M, the bank-switching was further
   improved, allowing the ROM to be paged out for another 16 kB of RAM.

   Such core changes brought incompatibilities:
     * Removal of several lines on the expansion bus edge connector
       (video, power, ROMCS and IORQGE); caused many external devices
       problems; some such as the VTX5000 modem could be used via the
       "FixIt" device
     * Reading a non-existent I/O port no longer returned the last
       attribute; caused some games such as Arkanoid to be unplayable
     * Memory timing changes; some of the RAM banks were now contended
       causing high-speed colour-changing effects to fail
     * The keypad scanning routines from the ROM were removed

   Some older 48K, and a few older 128K, games were incompatible with the
   machine.

   The +3 was the final official model of the Spectrum to be manufactured,
   remaining in production until December 1990. Although still accounting
   for one third of all home computer sales at the time, production of the
   model was ceased by Amstrad in an attempt to transfer customers to
   their CPC range.
   ZX Spectrum +2A.
   Enlarge
   ZX Spectrum +2A.

   The ZX Spectrum +2A was produced to homogenise Amstrad's range in 1987.
   Although the case reads "ZX Spectrum +2", the +2A/B is easily
   distinguishable from the original +2 as the case was restored to the
   standard Spectrum black.

   The +2A was derived from Amstrad's +3 4.1 ROM model, using 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. If an external disk drive was added, the "+2A"
   on the system OS menu would change to a +3. As with the ZX Spectrum +3,
   some older 48K, and a few older 128K, games were incompatible with the
   machine.

   The ZX Spectrum +2B signified a manufacturing move from Hong Kong to
   Taiwan later in 1987.

Clones

   Sinclair licensed the Spectrum design to Timex Corporation in the
   United States. An enhanced version of the Spectrum 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. However, 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 until
   Alan Sugar bought the computer side of Sinclair, when he took one look
   at it and ditched it (a conversation with UK computer journalist Guy
   Kewney went thus: AS: "Have you seen it?" GK: "Yes" AS: "Well then.").

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

   Many unofficial Spectrum clones were produced, especially in Eastern
   Bloc nations and South America (e.g. Microdigital TK 90X). In Russia
   for example, ZX Spectrum clones were assembled by thousands of small
   start-ups and distributed though poster ads and street stalls. Over 50
   such clone models existed. Some of them are still being produced, such
   as the Sprinter and ATM Turbo.

Peripherals

   Several peripherals for the Spectrum were marketed by Sinclair: the ZX
   Printer was already on the market, as the ZX Spectrum expansion bus was
   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. These
   were 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 ZX Interface 2 which added two
   joystick ports and a ROM cartridge port.
   Kempston joystick interface.
   Enlarge
   Kempston joystick interface.

   There were also 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), Videoface Digitiser, RAM pack, and Cheetah
   Marketing SpecDrum (Drum machine), and the Multiface (snapshot and
   disassembly tool), from Romantic Robot.

   There were numerous disk drive interfaces, including 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 many 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 also both compatible
   with the Microdrive command syntax, which made porting existing
   software much simpler.

   During the mid- 1980s, the company Micronet800 launched a service
   allowing users to connect their ZX Spectrums to a network known as
   Micronet hosted by Prestel. This service had some similarities to the
   Internet, but was proprietary and fee-based.

Software

   The Spectrum enjoys a vibrant, dedicated fan-base. Since it was cheap
   and simple to learn to use and program, the Spectrum was the starting
   point for many programmers and technophiles who remember it with
   nostalgia. The hardware limitations of the Spectrum imposed a special
   level of creativity on game designers, and for this reason, many
   Spectrum games are very creative and playable even by today's
   standards.

   The Spectrum family enjoyed a very large software library of at least
   13,000 titles. Though Spectrum hardware was limited by modern
   standards, its software library was very diverse, including programming
   language implementations, databases (eg: VU-File), word processors (eg:
   Tasword II), spreadsheets (eg: VU-Calc), drawing and painting tools
   (eg: James Hutchby's OCP Art Studio, Artist, Paintbox, Melbourne Draw),
   even 3D modelling. A huge quantity of games were released for the
   system.

Distribution

   Most Spectrum software was originally distributed on audio cassette
   tapes. The Spectrum was intended to work with almost any cassette tape
   player, and despite differences in audio reproduction fidelity, the
   software loading process was quite reliable.

   While the ZX Microdrive quickly became quite popular with the Spectrum
   user base due to the low cost of the drives, the actual media was very
   expensive for software publishers to use for mass market releases (by a
   factor of 10× compared to tape duplication). Furthermore, the
   cartridges themselves acquired a reputation for unreliability, and
   publishers were reluctant to QA each and every item shipped. Hence the
   main use became to complement tape releases, usually utilities and
   niche products like the Tasword word processing software and the
   aforementioned Trans Express. No games are known to be exclusively
   released on Microdrive.

   Despite the popularity of the DISCiPLE and +D systems, most software
   released for them took the form of utility software. The ZX Spectrum +3
   enjoyed much more success when it came to commercial software releases
   on floppy disk. More than 700 titles were released on 3-inch disk from
   1987 to 1997.

   Software was also distributed through print media, fan magazines and
   books. The prevalent language for distribution was the Spectrum's BASIC
   dialect Sinclair BASIC. The reader would type the software into the
   computer by hand, run it, and save it to tape for later use. The
   software distributed in this way was in general simpler and slower than
   its assembly language counterparts, and lacked graphics. But soon,
   magazines were printing long lists of checksummed hexadecimal digits
   with machine code games or tools. There was a vibrant scientific
   community built around such software, ranging from satellite dish
   alignment programs to school classroom scheduling programs.

   Another, unusual, 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
   e.g. Belgrade ( Ventilator 202), Poland, Czechoslovakia, Romania or
   Brazil, 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. Some magazines
   distributed 7" 33⅓ rpm "flexidisc" records, a variant of regular vinyl
   records, which could be played on a standard record player. These disks
   were known as " floppy ROMs".

Copying and backup software

   Most copier software available for the Spectrum was designed for
   copyright infringement of software through tape duplication. Copiers
   were developed to copy programs from audio tape to microdrive tapes,
   and later on diskettes. Complex loaders with unusual speeds or encoding
   were the basis of the Spectrum's copy prevention schemes, although
   other methods were used including asking for a particular word from the
   documentation included with the game — often a novella — or another
   physical device distributed in the software box. As protection became
   more complex it was almost impossible to use copiers to copy tapes, and
   the loaders had to be cracked by hand, to produce unprotected versions.
   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 digitized in recent years and is
   available for download in digital form. One popular program for
   digitizing Spectrum software 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. Once in digital form,
   the software can be executed on one of many existing emulators, on
   virtually any platform available today. Today, the largest on-line
   archive of ZX Spectrum software is World of Spectrum, with more than
   12,000 titles. The legality of this practice is still in question.
   However, it seems unlikely that any action will ever be taken over such
   so-called abandonware.

Famous Spectrum developers

   A number of current leading games developers and development companies
   began their careers on the ZX Spectrum, including Peter Molyneux (ex-
   Bullfrog Games), David Perry of Shiny Entertainment, and Ultimate Play
   The Game (now known as Rare, 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) and Sid Meier ( Silent Service)

Screenshots

   3D Deathchase

                Rebelstar

                         All or Nothing

                                       Rainbow Islands

   Chase HQ

                RoboCop

                         Elite

                                       Manic Miner

   Retrieved from " http://en.wikipedia.org/wiki/ZX_Spectrum"
   This reference article is mainly selected from the English Wikipedia
   with only minor checks and changes (see www.wikipedia.org for details
   of authors and sources) and is available under the GNU Free
   Documentation License. See also our Disclaimer.
