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Created page with "'''Home * Hardware * Sinclair ZX81''' FILE:Sinclair-ZX81.png|border|right|thumb| Sinclair ZX81 <ref>The Sinclair ZX81, a hobbyist home computer released i..."
'''[[Main Page|Home]] * [[Hardware]] * Sinclair ZX81'''
[[FILE:Sinclair-ZX81.png|border|right|thumb| Sinclair ZX81 <ref>The Sinclair ZX81, a hobbyist home computer released in the UK in 1981, [https://commons.wikimedia.org/wiki/File:Sinclair-ZX81.png photo] by [https://commons.wikimedia.org/wiki/User:Evan-Amos Evan-Amos], January 31, 2012, [https://en.wikipedia.org/wiki/Wikimedia_Commons Wikimedia Commons]</ref> ]]
'''Sinclair ZX81''', (ZX81, Timex Sinclair 1000)<br/>
a low-cost [https://en.wikipedia.org/wiki/Home_computer home computer] developed by [[Sinclair|Sinclair Research]] and manufactured in [https://en.wikipedia.org/wiki/Scotland Scotland] by [https://en.wikipedia.org/wiki/Timex_Group_USA Timex Corporation], launched in the [https://en.wikipedia.org/wiki/United_Kingdom UK] in March 1981, and as slightly modified [https://en.wikipedia.org/wiki/Timex_Sinclair_1000 Timex Sinclair 1000] in the [https://en.wikipedia.org/wiki/United_States US] in July 1982. The ZX81 consists of a 3.5 MHz [[Z80|Z80A]] CPU from [https://en.wikipedia.org/wiki/NEC Nippon Electric Company], an [https://en.wikipedia.org/wiki/Application-specific_integrated_circuit ASIC] dubbed Sinclair Computer Logic, an 8 [https://en.wikipedia.org/wiki/Kibibyte KiB] [[Memory#ROM|ROM]] with the [https://en.wikipedia.org/wiki/Operating_system operating system], the [[Basic#Sinclair|Sinclair BASIC]] interpreter, and one KiB of [[Memory#RAM|RAM]], which could be expanded externally to 16 KiB. For I/O it had a [https://en.wikipedia.org/wiki/Membrane_keyboard membrane keyboard], a [https://en.wikipedia.org/wiki/RF_modulator RF modulator] to output 24 lines x 32 [https://en.wikipedia.org/wiki/Characters_per_line characters] or 64x48 [https://en.wikipedia.org/wiki/Pixel pixel] as [https://en.wikipedia.org/wiki/Signal_%28electrical_engineering%29 signal] for a [https://en.wikipedia.org/wiki/Television television], and a [https://en.wikipedia.org/wiki/Serial_port serial port] and [https://en.wikipedia.org/wiki/Softmodem softmodem] <ref>[http://www.wearmouth.demon.co.uk/zx81.htm Assembly Listing of the Operating System of the Sinclair ZX81] - THE 'SAVE COMMAND' ROUTINE, THE 'LOAD COMMAND' ROUTINE</ref>, to store and load [[Program|programs]] and [[Data|data]] to or from an external [https://en.wikipedia.org/wiki/Audio_cassette audio cassette] [https://en.wikipedia.org/wiki/Tape_recorder recorder] with 250 [https://en.wikipedia.org/wiki/Baud baud] <ref>[https://en.wikipedia.org/wiki/ZX81 ZX81 from Wikipedia]</ref>.
[https://en.wikipedia.org/wiki/Jim_Westwood Jim Westwood's] technical dodge using [https://en.wikipedia.org/wiki/Non-maskable_interrupt non-maskable interrupts] solved the flicker problem of the [https://en.wikipedia.org/wiki/ZX80 ZX80] and gave the ZX81 a "multi-tasking" SLOW mode with a steady display <ref>[http://www.wearmouth.demon.co.uk/zx81.htm Assembly Listing of the Operating System of the Sinclair ZX81] - THE 'NON MASKABLE INTERRUPT' ROUTINE</ref>, slowing down programs fourfold <ref>[https://en.wikipedia.org/wiki/ZX81 ZX81 from Wikipedia]</ref>. [[Z80]] [https://en.wikipedia.org/wiki/Machine_code machine code] could be inlined at absolute addresses and called via USR <ref>[http://yourcomputeronline.wordpress.com/tag/stuart-nicholls/page/3/ Stuart Nicholls] ('''1982'''). ''[http://yourcomputeronline.wordpress.com/2012/09/22/zx-81-games-writing/ ZX-81 Games Writing]''. [[Your Computer]], [http://yourcomputeronline.wordpress.com/2011/11/13/november-1982-contents-and-editorial/ November 1982]</ref> or encoded in [https://en.wikipedia.org/wiki/Comment_%28computer_programming%29#BASIC comment lines] <ref>[[David Horne]] ('''1982'''). ''[http://yourcomputeronline.wordpress.com/2012/10/21/chess-in-1k/ Chess in 1K]''. [[Your Computer]], [http://yourcomputeronline.wordpress.com/2012/10/04/december-1982-contents-and-editorial/ December 1982]</ref>, which could be executed after some appropriate [https://en.wikipedia.org/wiki/PEEK_and_POKE POKE] instructions.
=Chess Programs=
The only chess program for the non expanded ZX81 in SLOW mode was [[1K ZX Chess]] by [[David Horne]]. Other programs, such as [[Artic Computing|Artic Computing's]] [[ZX Chess]], and [[Chris Whittington|Chris Whittington's]] [[SuperChess]], require the 16 KB memory expansion.
* [[:Category:ZX81|ZX81 Chess Programs]]
=See also=
* [[TRS-80]]
* [[ZX Spectrum]]
=Publications=
* [http://brooknet.no-ip.com/~lex/public/zx81/zx81_assembly_instructions.pdf ZX81 Assembly Instructions] (pdf)
* [http://www.classiccmp.org/cini/pdf/random/Timex-Sinclair%20ZX81%20Assembly.pdf ZX81 Assembly Instructions U.S. Version for UHF Channel 33] (pdf)
* [http://yourcomputeronline.wordpress.com/tag/brendon-gore/ Brendon Gore] ('''1982'''). ''[http://yourcomputeronline.wordpress.com/2011/02/27/interview-one-degree-in-artic/ Interview-One Degree In Artic]''. [[Your Computer]], [http://yourcomputeronline.wordpress.com/2011/02/23/may-1982-contents-and-editorial/ May 1982]
* [[David Horne]] ('''1982'''). ''[http://yourcomputeronline.wordpress.com/2011/05/24/zx-81-disassembler/ ZX-81 Disassembler]''. [[Your Computer]], [http://yourcomputeronline.wordpress.com/2011/04/20/july-1982-contents-and-editorial/ July 1982]
* [http://yourcomputeronline.wordpress.com/tag/stuart-nicholls/page/3/ Stuart Nicholls] ('''1982'''). ''[http://yourcomputeronline.wordpress.com/2012/09/22/zx-81-games-writing/ ZX-81 Games Writing]''. [[Your Computer]], [http://yourcomputeronline.wordpress.com/2011/11/13/november-1982-contents-and-editorial/ November 1982]
* [[David Horne]] ('''1982'''). ''[http://yourcomputeronline.wordpress.com/2012/10/21/chess-in-1k/ Chess in 1K]''. [[Your Computer]], [http://yourcomputeronline.wordpress.com/2012/10/04/december-1982-contents-and-editorial/ December 1982]
* [[David Horne]] ('''1983'''). ''ZX-81 Chess''. [[Your Computer]], [http://yourcomputeronline.wordpress.com/2012/11/03/january-1983-contents-and-editorial/ January 1983]
* [[David Horne]] ('''1983'''). ''[http://users.ox.ac.uk/~uzdm0006/scans/1kchess/ Full ZX-81 Chess in 1K]''. [[Your Computer]], February 1983
=Forum Posts=
* [https://groups.google.com/d/msg/comp.lang.c/GamjraXyeR4/GKUiyZvoTlgJ World smallest chess program] by [[Óscar Toledo Gutiérrez]], [http://groups.google.com/group/comp.lang.c/topics comp.lang.c], November 22, 2006
* [http://www.schachcomputer.info/forum/f11/schachcomputer-vergleich-zu-alte-computerschach-spiele-1948-2.html Turnier: Schachcomputer vergleich zu alte Computerschach Spiele] by [[The Spacious Mind|Spacious Mind]], [http://www.schachcomputer.info/forum/portal.php Schachcomputer.info Forum], August 12, 2008 (German)
=External Links=
* [https://en.wikipedia.org/wiki/ZX81 ZX81 from Wikipedia]
* [https://en.wikipedia.org/wiki/ZX80 ZX80 from Wikipedia]
* [https://en.wikipedia.org/wiki/Timex_Sinclair_1000 Timex Sinclair 1000 from Wikipedia]
* [https://en.wikipedia.org/wiki/List_of_ZX80_and_ZX81_clones List of ZX80 and ZX81 clones from Wikipedia]
* [http://www.honneamise.u-net.com/zx81/ ZX81 Home Page]
* [http://www.spacious-mind.com/html/timex_sinclair_1000.html Timex Sinclair 1000 - Old Home Computers Collection] from [[The Spacious Mind]]
=References=
<references />
'''[[Hardware|Up one Level]]'''
[[FILE:Sinclair-ZX81.png|border|right|thumb| Sinclair ZX81 <ref>The Sinclair ZX81, a hobbyist home computer released in the UK in 1981, [https://commons.wikimedia.org/wiki/File:Sinclair-ZX81.png photo] by [https://commons.wikimedia.org/wiki/User:Evan-Amos Evan-Amos], January 31, 2012, [https://en.wikipedia.org/wiki/Wikimedia_Commons Wikimedia Commons]</ref> ]]
'''Sinclair ZX81''', (ZX81, Timex Sinclair 1000)<br/>
a low-cost [https://en.wikipedia.org/wiki/Home_computer home computer] developed by [[Sinclair|Sinclair Research]] and manufactured in [https://en.wikipedia.org/wiki/Scotland Scotland] by [https://en.wikipedia.org/wiki/Timex_Group_USA Timex Corporation], launched in the [https://en.wikipedia.org/wiki/United_Kingdom UK] in March 1981, and as slightly modified [https://en.wikipedia.org/wiki/Timex_Sinclair_1000 Timex Sinclair 1000] in the [https://en.wikipedia.org/wiki/United_States US] in July 1982. The ZX81 consists of a 3.5 MHz [[Z80|Z80A]] CPU from [https://en.wikipedia.org/wiki/NEC Nippon Electric Company], an [https://en.wikipedia.org/wiki/Application-specific_integrated_circuit ASIC] dubbed Sinclair Computer Logic, an 8 [https://en.wikipedia.org/wiki/Kibibyte KiB] [[Memory#ROM|ROM]] with the [https://en.wikipedia.org/wiki/Operating_system operating system], the [[Basic#Sinclair|Sinclair BASIC]] interpreter, and one KiB of [[Memory#RAM|RAM]], which could be expanded externally to 16 KiB. For I/O it had a [https://en.wikipedia.org/wiki/Membrane_keyboard membrane keyboard], a [https://en.wikipedia.org/wiki/RF_modulator RF modulator] to output 24 lines x 32 [https://en.wikipedia.org/wiki/Characters_per_line characters] or 64x48 [https://en.wikipedia.org/wiki/Pixel pixel] as [https://en.wikipedia.org/wiki/Signal_%28electrical_engineering%29 signal] for a [https://en.wikipedia.org/wiki/Television television], and a [https://en.wikipedia.org/wiki/Serial_port serial port] and [https://en.wikipedia.org/wiki/Softmodem softmodem] <ref>[http://www.wearmouth.demon.co.uk/zx81.htm Assembly Listing of the Operating System of the Sinclair ZX81] - THE 'SAVE COMMAND' ROUTINE, THE 'LOAD COMMAND' ROUTINE</ref>, to store and load [[Program|programs]] and [[Data|data]] to or from an external [https://en.wikipedia.org/wiki/Audio_cassette audio cassette] [https://en.wikipedia.org/wiki/Tape_recorder recorder] with 250 [https://en.wikipedia.org/wiki/Baud baud] <ref>[https://en.wikipedia.org/wiki/ZX81 ZX81 from Wikipedia]</ref>.
[https://en.wikipedia.org/wiki/Jim_Westwood Jim Westwood's] technical dodge using [https://en.wikipedia.org/wiki/Non-maskable_interrupt non-maskable interrupts] solved the flicker problem of the [https://en.wikipedia.org/wiki/ZX80 ZX80] and gave the ZX81 a "multi-tasking" SLOW mode with a steady display <ref>[http://www.wearmouth.demon.co.uk/zx81.htm Assembly Listing of the Operating System of the Sinclair ZX81] - THE 'NON MASKABLE INTERRUPT' ROUTINE</ref>, slowing down programs fourfold <ref>[https://en.wikipedia.org/wiki/ZX81 ZX81 from Wikipedia]</ref>. [[Z80]] [https://en.wikipedia.org/wiki/Machine_code machine code] could be inlined at absolute addresses and called via USR <ref>[http://yourcomputeronline.wordpress.com/tag/stuart-nicholls/page/3/ Stuart Nicholls] ('''1982'''). ''[http://yourcomputeronline.wordpress.com/2012/09/22/zx-81-games-writing/ ZX-81 Games Writing]''. [[Your Computer]], [http://yourcomputeronline.wordpress.com/2011/11/13/november-1982-contents-and-editorial/ November 1982]</ref> or encoded in [https://en.wikipedia.org/wiki/Comment_%28computer_programming%29#BASIC comment lines] <ref>[[David Horne]] ('''1982'''). ''[http://yourcomputeronline.wordpress.com/2012/10/21/chess-in-1k/ Chess in 1K]''. [[Your Computer]], [http://yourcomputeronline.wordpress.com/2012/10/04/december-1982-contents-and-editorial/ December 1982]</ref>, which could be executed after some appropriate [https://en.wikipedia.org/wiki/PEEK_and_POKE POKE] instructions.
=Chess Programs=
The only chess program for the non expanded ZX81 in SLOW mode was [[1K ZX Chess]] by [[David Horne]]. Other programs, such as [[Artic Computing|Artic Computing's]] [[ZX Chess]], and [[Chris Whittington|Chris Whittington's]] [[SuperChess]], require the 16 KB memory expansion.
* [[:Category:ZX81|ZX81 Chess Programs]]
=See also=
* [[TRS-80]]
* [[ZX Spectrum]]
=Publications=
* [http://brooknet.no-ip.com/~lex/public/zx81/zx81_assembly_instructions.pdf ZX81 Assembly Instructions] (pdf)
* [http://www.classiccmp.org/cini/pdf/random/Timex-Sinclair%20ZX81%20Assembly.pdf ZX81 Assembly Instructions U.S. Version for UHF Channel 33] (pdf)
* [http://yourcomputeronline.wordpress.com/tag/brendon-gore/ Brendon Gore] ('''1982'''). ''[http://yourcomputeronline.wordpress.com/2011/02/27/interview-one-degree-in-artic/ Interview-One Degree In Artic]''. [[Your Computer]], [http://yourcomputeronline.wordpress.com/2011/02/23/may-1982-contents-and-editorial/ May 1982]
* [[David Horne]] ('''1982'''). ''[http://yourcomputeronline.wordpress.com/2011/05/24/zx-81-disassembler/ ZX-81 Disassembler]''. [[Your Computer]], [http://yourcomputeronline.wordpress.com/2011/04/20/july-1982-contents-and-editorial/ July 1982]
* [http://yourcomputeronline.wordpress.com/tag/stuart-nicholls/page/3/ Stuart Nicholls] ('''1982'''). ''[http://yourcomputeronline.wordpress.com/2012/09/22/zx-81-games-writing/ ZX-81 Games Writing]''. [[Your Computer]], [http://yourcomputeronline.wordpress.com/2011/11/13/november-1982-contents-and-editorial/ November 1982]
* [[David Horne]] ('''1982'''). ''[http://yourcomputeronline.wordpress.com/2012/10/21/chess-in-1k/ Chess in 1K]''. [[Your Computer]], [http://yourcomputeronline.wordpress.com/2012/10/04/december-1982-contents-and-editorial/ December 1982]
* [[David Horne]] ('''1983'''). ''ZX-81 Chess''. [[Your Computer]], [http://yourcomputeronline.wordpress.com/2012/11/03/january-1983-contents-and-editorial/ January 1983]
* [[David Horne]] ('''1983'''). ''[http://users.ox.ac.uk/~uzdm0006/scans/1kchess/ Full ZX-81 Chess in 1K]''. [[Your Computer]], February 1983
=Forum Posts=
* [https://groups.google.com/d/msg/comp.lang.c/GamjraXyeR4/GKUiyZvoTlgJ World smallest chess program] by [[Óscar Toledo Gutiérrez]], [http://groups.google.com/group/comp.lang.c/topics comp.lang.c], November 22, 2006
* [http://www.schachcomputer.info/forum/f11/schachcomputer-vergleich-zu-alte-computerschach-spiele-1948-2.html Turnier: Schachcomputer vergleich zu alte Computerschach Spiele] by [[The Spacious Mind|Spacious Mind]], [http://www.schachcomputer.info/forum/portal.php Schachcomputer.info Forum], August 12, 2008 (German)
=External Links=
* [https://en.wikipedia.org/wiki/ZX81 ZX81 from Wikipedia]
* [https://en.wikipedia.org/wiki/ZX80 ZX80 from Wikipedia]
* [https://en.wikipedia.org/wiki/Timex_Sinclair_1000 Timex Sinclair 1000 from Wikipedia]
* [https://en.wikipedia.org/wiki/List_of_ZX80_and_ZX81_clones List of ZX80 and ZX81 clones from Wikipedia]
* [http://www.honneamise.u-net.com/zx81/ ZX81 Home Page]
* [http://www.spacious-mind.com/html/timex_sinclair_1000.html Timex Sinclair 1000 - Old Home Computers Collection] from [[The Spacious Mind]]
=References=
<references />
'''[[Hardware|Up one Level]]'''
