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ZX81

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ZX81

The ZX81 is a home computer developed 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 designed to be a low-cost introduction to home computing for the general public. It was hugely successful; more than 1.5 million units were sold. In the United States it was initially sold as the ZX-81 under licence by Timex. Timex later produced its own versions of the ZX81: the Timex Sinclair 1000 and Timex Sinclair 1500. Unauthorized ZX81 clones were produced in several countries. The ZX81 was designed to be small, simple, and above all, inexpensive. Video output is for a television set rather than a dedicated monitor. It contains only four silicon chips and 1 KB of RAM. It has no power switch or moving parts, excepting a VHF TV channel selector switch in some models. It has a pressure-sensitive membrane keyboard. Programs and data are loaded and saved onto compact audio cassettes. The ZX81's limitations prompted a market in third-party peripherals to improve its capabilities. Its distinctive case and keyboard brought designer Rick Dickinson a Design Council award. The ZX81 could be bought by mail order preassembled or, for a lower price, in kit form. It was the first inexpensive mass-market home computer to be sold by high street stores, led by W. H. Smith and soon many other retailers. The ZX81 marked the point when computing in Britain became an activity for the general public rather than businessmen and electronics hobbyists. It produced a community of enthusiasts, some of whom founded businesses developing software and hardware for the ZX81. Many went on to have roles in the British computer industry. The ZX81's commercial success made Sinclair Research one of Britain's leading computer manufacturers and earned a fortune and an eventual knighthood for the company's founder, Sir Clive Sinclair. The system was discontinued in 1984.

Infobox

Developer
Sinclair Research
Manufacturer
Timex Corporation
Type
Home computer
Release date
5 March 1981; 44 years ago (1981-03-05)
Introductory price
£49.95 kit, £69.95 assembled (£242–339/$332–464 at 2023 prices)
Discontinued
1984
Units sold
More than 1.5 million
Operating system
Sinclair BASIC
CPU
Z80 @ 3.25 MHz
Memory
1 KB (64 KB max. 56 KB usable)
Storage
External Compact Cassette recorder at a claimed 250 bit/s or an average 300 bit/s
Display
Monochrome display on UHF television
Graphics
24 lines × 32 characters or 64 × 48 pixels graphics mode
Power
9V DC
Dimensions
167 millimetres (6.6 in) wide by 175 millimetres (6.9 in) deep
Weight
350 grams (12 oz)
Predecessor
ZX80
Successor
ZX Spectrum
Related
Timex Sinclair 1000,Timex Sinclair 1500

Tables

· Features › Comparisons with other computing devices
Apple II Plus
Apple II Plus
Device
Apple II Plus
RAMstan­dard
16 KB
Expand­able to
48 KB
CPU
MOS Technology 6502 @ 1 MHz (8-bit)
Keyboard
Typewriter
BASIC
Integer only
Sale price
£549
Number ofcolours
16
Maximumresolution
280 × 192 pixels
Sound
beeper
Atari 400
Atari 400
Device
Atari 400
RAMstan­dard
8 KB
Expand­able to
48 KB
CPU
MOS Technology 6502 @ 1.78 MHz
Keyboard
Membrane
BASIC
extra
Sale price
£289
Number ofcolours
256
Maximumresolution
320 × 192 pixels
Sound
4 voice
PET
PET
Device
PET
RAMstan­dard
16 KB
Expand­able to
40 KB
CPU
MOS Technology 6502 @ 1 MHz
Keyboard
Typewriter
BASIC
MS Level I
Sale price
£399
Number ofcolours
Monochrome
Maximumresolution
320 × 200 text only
Sound
beeper
VIC-20
VIC-20
Device
VIC-20
RAMstan­dard
5 KB
Expand­able to
32 KB
CPU
MOS Technology 6502 @ 1.02 MHz
Keyboard
Typewriter
BASIC
MS Level I
Sale price
£189
Number ofcolours
8
Maximumresolution
176 × 184 pixels
Sound
4 voice
Video Genie
Video Genie
Device
Video Genie
RAMstan­dard
16 KB
Expand­able to
48 KB
CPU
Zilog Z80 @ 1.76 MHz
Keyboard
Typewriter
BASIC
MS Level II
Sale price
£279
Number ofcolours
Monochrome
Maximumresolution
128 × 48 block
Sound
beeper
Compukit 101
Compukit 101
Device
Compukit 101
RAMstan­dard
1 KB
Expand­able to
48 KB
CPU
MOS Technology 6502 @ 1 MHz
Keyboard
Typewriter
BASIC
MS Level II
Sale price
£149/£199 assembled
Number ofcolours
Monochrome
Maximumresolution
128 × 48 block
Sound
extra
TRS-80 Model I
TRS-80 Model I
Device
TRS-80 Model I
RAMstan­dard
4 KB
Expand­able to
48 KB
CPU
Zilog Z80 @ 1.78 MHz (8-bit)
Keyboard
Typewriter
BASIC
Restricted
Sale price
£399
Number ofcolours
Monochrome
Maximumresolution
128 × 48 block
Sound
extra
Acorn Atom
Acorn Atom
Device
Acorn Atom
RAMstan­dard
2 KB
Expand­able to
12 KB
CPU
MOS Technology 6502 @ 1 MHz
Keyboard
Typewriter
BASIC
TinyBASIC hybrid
Sale price
£140/£173 assembled
Number ofcolours
8
Maximumresolution
256 × 192 mono, 64 × 64 colour
Sound
beeper
MicroTan
MicroTan
Device
MicroTan
RAMstan­dard
1 KB
Expand­able to
48 KB
CPU
MOS Technology 6502 @ 0.75 MHz
Keyboard
extra
BASIC
extra
Sale price
£65/£99 assembled
Number ofcolours
Monochrome
Maximumresolution
128 × 48 block
Sound
extra
TI-99/4A
TI-99/4A
Device
TI-99/4A
RAMstan­dard
16 KB
Expand­able to
48 KB
CPU
TI TMS9900 @ 3.0 MHz (16-bit)
Keyboard
Typewriter
BASIC
Restricted
Sale price
£399
Number ofcolours
16
Maximumresolution
256 × 192 pixels
Sound
3 voices and white noise
ZX81 / TS1000
ZX81 / TS1000
Device
ZX81 / TS1000
RAMstan­dard
1 KB / 2 KB
Expand­able to
32 KB
CPU
Zilog or NEC Z80 @ 3.25 MHz (8-bit)
Keyboard
Membrane
BASIC
MS Level II equiv.
Sale price
£49/£69 assembled
Number ofcolours
Monochrome
Maximumresolution
64 × 48 block
Sound
No
Device
RAMstan­dard
Expand­able to
CPU
Keyboard
BASIC
Sale price
Number ofcolours
Maximumresolution
Sound
Apple II Plus
16 KB
48 KB
MOS Technology 6502 @ 1 MHz (8-bit)
Typewriter
Integer only
£549
16
280 × 192 pixels
beeper
Atari 400
8 KB
48 KB
MOS Technology 6502 @ 1.78 MHz
Membrane
extra
£289
256
320 × 192 pixels
4 voice
PET
16 KB
40 KB
MOS Technology 6502 @ 1 MHz
Typewriter
MS Level I
£399
Monochrome
320 × 200 text only
beeper
VIC-20
5 KB
32 KB
MOS Technology 6502 @ 1.02 MHz
Typewriter
MS Level I
£189
8
176 × 184 pixels
4 voice
Video Genie
16 KB
48 KB
Zilog Z80 @ 1.76 MHz
Typewriter
MS Level II
£279
Monochrome
128 × 48 block
beeper
Compukit 101
1 KB
48 KB
MOS Technology 6502 @ 1 MHz
Typewriter
MS Level II
£149/£199 assembled
Monochrome
128 × 48 block
extra
TRS-80 Model I
4 KB
48 KB
Zilog Z80 @ 1.78 MHz (8-bit)
Typewriter
Restricted
£399
Monochrome
128 × 48 block
extra
Acorn Atom
2 KB
12 KB
MOS Technology 6502 @ 1 MHz
Typewriter
TinyBASIC hybrid
£140/£173 assembled
8
256 × 192 mono, 64 × 64 colour
beeper
MicroTan
1 KB
48 KB
MOS Technology 6502 @ 0.75 MHz
extra
extra
£65/£99 assembled
Monochrome
128 × 48 block
extra
TI-99/4A
16 KB
48 KB
TI TMS9900 @ 3.0 MHz (16-bit)
Typewriter
Restricted
£399
16
256 × 192 pixels
3 voices and white noise
ZX81 / TS1000
1 KB / 2 KB
32 KB
Zilog or NEC Z80 @ 3.25 MHz (8-bit)
Membrane
MS Level II equiv.
£49/£69 assembled
Monochrome
64 × 48 block
No

References

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  2. Everyday Electronics (April 1981)
  3. "Sinclair ZX81"
    https://web.archive.org/web/20141214131822/http://www.sinclairzx.com/about-us.html#12
  4. ZX81 Operating Supplement (1982)
  5. "Sinclair ZX81 Data Tapes"
    http://www.myprius.co.za/tape_storage.htm
  6. ZX Computing
    https://archive.org/details/ZXComputingJunJul1985/ZXComputing/ZXComputing_Oct-Nov_1982/page/n129
  7. The Computers That Made Britain — The Home Computer Revolution of the 1980s
    https://archive.org/details/computers-that-made-britain
  8. Thomasson 1983, p. 40.
  9. Thomasson 1983, p. 14.
  10. New Scientist (7 February 1980).
  11. For comparisons of processing speed in the two modes, see "ZX81 v IBM PC", Which Micro?, April 1983, p. 36.
  12. Thomasson 1983, p. 13.
  13. Thomasson 1983, p. 26.
  14. Your Computer
    https://archive.org/stream/YourComputer_198302/YourComputer8302#page/n99/mode/2up
  15. Nash 1984, p. 102.
  16. Thomasson 1983, p. 43.
  17. Ars Technica
    https://arstechnica.com/gaming/2021/09/rip-sir-clive-sinclair-creator-of-uks-famed-zx-spectrum-gaming-computer/
  18. Electronics Weekly
    https://www.electronicsweekly.com/news/business/uncle-clive-2021-09/
  19. Tech Digest
    https://www.techdigest.tv/2021/09/sir-clive-sinclair-rip-10-things-about-the-great-man-you-may-not-know.html
  20. www.computinghistory.org.uk
    https://www.computinghistory.org.uk/det/184/Sinclair-ZX81-Issue-One/
  21. Dale 1985, p. 39.
  22. Adamson & Kennedy 1986, p. 31.
  23. Adamson & Kennedy 1986, p. 35.
  24. Adamson & Kennedy 1986, p. 36.
  25. Adamson & Kennedy 1986, p. 39.
  26. Adamson & Kennedy 1986, p. 65.
  27. Adamson & Kennedy 1986, p. 66.
  28. Adamson & Kennedy 1986, p. 68.
  29. Adamson & Kennedy 1986, p. 86.
  30. Hayman (June 1982)
  31. IEEE Spectrum
    https://spectrum.ieee.org/build-your-own-altair-8800-personal-computer
  32. PCMAG
    https://www.pcmag.com/news/45-years-ago-apple-kickstarted-the-personal-computer-industry
  33. Valéry 1977.
  34. Dale 1985, p. 95.
  35. Adamson & Kennedy 1986, p. 80.
  36. MK14 advertisement (1978)
  37. Adamson & Kennedy 1986, p. 81.
  38. Adamson & Kennedy 1986, p. 61.
  39. measuringworth.com
    https://www.measuringworth.com/calculators/ukcompare/result.php?year_source=1980&amount=99.95&year_result=2021
  40. Lorenz (15 April 1982)
  41. Scot (Aug/Sept 1981)
  42. BBC News (23 April 2007)
  43. Adamson & Kennedy 1986, p. 90.
  44. Dale 1985, p. 97.
  45. Dale 1985, p. 102.
  46. Crisp (20 March 1982)
  47. Adamson & Kennedy 1986, p. 256.
  48. Dale 1985, p. 100.
  49. Dale 1985, p. 103.
  50. Dale 1985, p. 104.
  51. Adamson & Kennedy 1986, p. 104.
  52. Adamson & Kennedy 1986, pp. 116–117.
  53. Gore (March 1982)
  54. Engineering Today (22 February 1982)
  55. Dale 1985, pp. 106–7.
  56. Campbell 1983.
  57. McClelland 2011.
  58. timexsinclair.com
    https://www.timexsinclair.com/computers/sinclair-zx81/
  59. Adamson & Kennedy 1986, p. 103.
  60. Sinclair (26 June 1986)
  61. CRASH (May 1985)
  62. Goodwin (Jan 1988)
  63. Gillies-Jones (22 June 2000)
  64. Adamson & Kennedy 1986, pp. 89–90.
  65. Adamson & Kennedy 1986, p. 105.
  66. Adamson & Kennedy 1986, pp. 107–8.
  67. Adamson & Kennedy 1986, p. 106.
  68. Phillips (April 1983)
  69. Laing 2004, p. 61.
  70. Dickinson (24 August 2007)
  71. Cooke (August 1982)
  72. McManus Galleries
  73. Adamson & Kennedy 1986, p. 94.
  74. Church (May 1982)
  75. Adamson & Kennedy 1986, p. 111.
  76. Adamson & Kennedy 1986, p. 112.
  77. Adamson & Kennedy 1986, p. 133.
  78. Clarke (11 February 1982)
  79. Adamson & Kennedy 1986, p. 108.
  80. Adamson & Kennedy 1986, p. 97.
  81. Adamson & Kennedy 1986, p. 99.
  82. Adamson & Kennedy 1986.
  83. Adamson & Kennedy 1986, p. 21.
  84. Popular Science (October 1982)
  85. Adamson & Kennedy 1986, p. 22.
  86. Adamson & Kennedy 1986, p. 98.
  87. Adamson & Kennedy 1986, p. 114.
  88. Sinclair Research sales brochure (1981)
  89. Adamson & Kennedy 1986, p. 143.
  90. The Age
    https://news.google.com/newspapers?id=ByBVAAAAIBAJ&pg=3739%2C4130406
  91. BYTE
    https://archive.org/details/byte-magazine-1982-09/page/n488/mode/1up?view=theater
  92. Adamson & Kennedy 1986, p. 259.
  93. Adamson & Kennedy 1986, p. 109.
  94. Hartnell (November 1981)
  95. Taylor (21 November 1981)
  96. Adamson & Kennedy 1986, p. 257.
  97. Needle (15 March 1982)
  98. Wise (2 November 1981)
  99. Crisp (13 February 1982)
  100. Adamson & Kennedy 1986, pp. 108–09.
  101. BYTE (August 1982)
  102. Shibata (30 September 1982)
  103. The Home Computer Museum
    http://www.homecomputer.de/pages/f_info.html?Sinclair_ZX-81_Beocomp.html
  104. Daily Telegraph (30 May 1983)
  105. Sinclair User (November 1983)
  106. Hartnell (June–July 1981)
  107. Peltu (30 April 1981)
  108. Tebbutt (June 1981)
  109. Garrett 1983.
  110. InfoWorld
    https://books.google.com/books?id=4S8EAAAAMBAJ&pg=PA55
  111. Babsky (April 1983)
  112. Adamson & Kennedy 1986, p. 96.
  113. Adamson & Kennedy 1986, p. 107.
  114. BYTE (June 1982)
  115. Dale 1985, p. 108.
  116. Kewney (3 May 1982)
  117. Retrogames
    http://www.retrogames.co.uk/016196/Sinclair/The-8th-ZX-Microfair-Showguide
  118. Crash
    https://www.crashonline.org.uk/12/news.htm
  119. Morris 2007, p. 20.
  120. Bridgewater & Doyle 1998, pp. 156–157.
  121. Munford (March 1984).
  122. Sinclair User (April 1984)
  123. Adamson & Kennedy 1986, p. 121.
  124. Adamson & Kennedy 1986, p. 134.
  125. Adamson & Kennedy 1986, p. 140.
  126. Adamson & Kennedy 1986, p. 135.
  127. Adamson & Kennedy 1986, p. 137.
  128. Adamson & Kennedy 1986, p. 136.
  129. inCider
    https://archive.org/stream/inCider_83-11#page/n5/mode/2up
  130. Adamson & Kennedy 1986, p. 141.
  131. Sinclair User
    https://archive.org/stream/sinclair-user-magazine-012/SinclairUser_012_Mar_1983#page/n81/mode/2up
  132. Museu da Computação e Informática
  133. AlchNews
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  135. BBC News (8 August 2003)
  136. Krotoski (3-11-2003)
  137. Mackintosh (27 January 2000)
  138. Mackintosh (23 September 1999)
  139. Joscelyne (5 November 2009)
  140. Cecco (June 1988)
  141. Eddy (July 1987)
  142. Hancock (15 September 1996)
  143. BBC News (4 July 2003)
  144. Reynolds (28 June 2009)
  145. Wallis (15 February 2007)
  146. forum.tlienhard.com
    http://forum.tlienhard.com/phpBB3/viewforum.php?f=2
  147. "Sinclair ZX80 / ZX81 Forums"
    https://web.archive.org/web/20091020132306/http://www.rwapservices.co.uk/ZX80_ZX81/forums/
  148. "Siggis ZX81 web server main page"
    https://web.archive.org/web/20120627081527/http://zx81-siggi.endoftheinternet.org/index.html
  149. RWAP Software
    http://www.rwapsoftware.co.uk/zx812.html
  150. Cronosoft
    https://cronosoft.fwscart.com/ZX81/cat5357733_4119465.aspx
  151. Revival Studios ZX81 games
    https://archive.today/20130615052550/http://zx81.revival-studios.com/
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