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'''Sinclair ZX81''', (ZX81, Timex Sinclair 1000)<br/>
 
'''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>.  
 
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.  
+
[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'''). ''Chess in 1K''. [[Your Computer]], December 1982</ref>, which could be executed after some appropriate [https://en.wikipedia.org/wiki/PEEK_and_POKE POKE] instructions.  
  
 
=Chess Programs=  
 
=Chess Programs=  
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* [http://brooknet.no-ip.com/~lex/public/zx81/zx81_assembly_instructions.pdf ZX81 Assembly Instructions] (pdf)
 
* [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://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]
+
* [https://magazinesfromthepast.fandom.com/wiki/Brendon_Gore Brendon Gore] ('''1982'''). ''Interview-One Degree In Artic''. [[Your Computer]], 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]
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* [[David Horne]] ('''1982'''). ''ZX-81 Disassembler''. [[Your Computer]], July 1982
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* [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]
+
* [http://yourcomputeronline.wordpress.com/tag/stuart-nicholls/page/3/ Stuart Nicholls] ('''1982'''). ''ZX-81 Games Writing''. [[Your Computer]], 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]
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* [[David Horne]] ('''1982'''). ''Chess in 1K''. [[Your Computer]], December 1982
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* [[David Horne]] ('''1983'''). ''ZX-81 Chess''. [[Your Computer]], [http://yourcomputeronline.wordpress.com/2012/11/03/january-1983-contents-and-editorial/ January 1983]
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* [[David Horne]] ('''1983'''). ''ZX-81 Chess''. [[Your Computer]], January 1983
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* [[David Horne]] ('''1983'''). ''[http://users.ox.ac.uk/~uzdm0006/scans/1kchess/ Full ZX-81 Chess in 1K]''. [[Your Computer]], February 1983
+
* [[David Horne]] ('''1983'''). ''[https://users.ox.ac.uk/~uzdm0006/scans/1kchess/ Full ZX-81 Chess in 1K]''. [[Your Computer]], February 1983
  
 
=Forum Posts=  
 
=Forum Posts=  

Latest revision as of 12:47, 4 July 2021

Home * Hardware * Sinclair ZX81

Sinclair ZX81 [1]

Sinclair ZX81, (ZX81, Timex Sinclair 1000)
a low-cost home computer developed by Sinclair Research and manufactured in Scotland by Timex Corporation, launched in the UK in March 1981, and as slightly modified Timex Sinclair 1000 in the US in July 1982. The ZX81 consists of a 3.5 MHz Z80A CPU from Nippon Electric Company, an ASIC dubbed Sinclair Computer Logic, an 8 KiB ROM with the operating system, the Sinclair BASIC interpreter, and one KiB of RAM, which could be expanded externally to 16 KiB. For I/O it had a membrane keyboard, a RF modulator to output 24 lines x 32 characters or 64x48 pixel as signal for a television, and a serial port and softmodem [2], to store and load programs and data to or from an external audio cassette recorder with 250 baud [3]. Jim Westwood's technical dodge using non-maskable interrupts solved the flicker problem of the ZX80 and gave the ZX81 a "multi-tasking" SLOW mode with a steady display [4], slowing down programs fourfold [5]. Z80 machine code could be inlined at absolute addresses and called via USR [6] or encoded in comment lines [7], which could be executed after some appropriate 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's ZX Chess, and Chris Whittington's SuperChess, require the 16 KB memory expansion.

See also

Publications

Forum Posts

External Links

References

  1. ↑ The Sinclair ZX81, a hobbyist home computer released in the UK in 1981, photo by Evan-Amos, January 31, 2012, Wikimedia Commons
  2. ↑ Assembly Listing of the Operating System of the Sinclair ZX81 - THE 'SAVE COMMAND' ROUTINE, THE 'LOAD COMMAND' ROUTINE
  3. ↑ ZX81 from Wikipedia
  4. ↑ Assembly Listing of the Operating System of the Sinclair ZX81 - THE 'NON MASKABLE INTERRUPT' ROUTINE
  5. ↑ ZX81 from Wikipedia
  6. ↑ Stuart Nicholls (1982). ZX-81 Games Writing. Your Computer, November 1982
  7. ↑ David Horne (1982). Chess in 1K. Your Computer, December 1982

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