Sinclair ZX81

Developer: Sinclair Research
Manufacturer: Timex Corporation
Release date: 5 March 1981
Discontinued: 1984
Type: Home Computer
Predecessor: ZX80
Successor: ZX Spectrum
Operating system: Sinclair BASIC
CPU: Z80 at 3.25 MHz
Storage capacity: External cassette tape recorder at 250 baud
Memory: 1 KB (64 KB max. 56 KB usable)
Display: Monochrome display on UHF television
Graphics: 24 lines x 32 characters or 64 x 48 pixels graphics mode
Highlights:
The computer is composed of only four IC chips, and there are no video chips or co-processors. The CPU has to perform all of the tasks that are required of a computer, which means it executes the BASIC program and updates the screen at the same time, slowing the program speed. The fix? Don't update the display as often - the SLOW and FAST commands determine the video display rate. The FAST command allows the program to run 4X faster, but then the display gets jerky.
Other models:
Timex Sinclair 1000, 1982, sold by Timex in USA
Timex Sinclair 1500, 1983, sold by Timex in USA, stop-gap between the TS 1000 and the forthcoming American version of the Spectrum, the TS 2000 (never released). It was a ZX81 with an internally housed 16K RAM expansion module, in a black and silver Spectrum-style box with the familiar "dead flesh" rubber keyboard. The updating of the ZX81 design was an attempt to counter the two biggest drawbacks of the TS 1000, namely the touch-sensitive keyboard and the minuscule 1K of memory. The machine failed dismally: no matter how much it was dressed up, it was still a ZX81, with most of that machine's limitations still intact.

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Sinclair ZX81

Developer: Sinclair Research
Manufacturer: Timex Corporation
Release date: 5 March 1981
Discontinued: 1984
Type: Home Computer
Predecessor: ZX80
Successor: ZX Spectrum
Operating system: Sinclair BASIC
CPU: Z80 at 3.25 MHz
Storage capacity: External cassette tape recorder at 250 baud
Memory: 1 KB (64 KB max. 56 KB usable)
Display: Monochrome display on UHF television
Graphics: 24 lines x 32 characters or 64 x 48 pixels graphics mode
Highlights:
The computer is composed of only four IC chips, and there are no video chips or co-processors. The CPU has to perform all of the tasks that are required of a computer, which means it executes the BASIC program and updates the screen at the same time, slowing the program speed. The fix? Don't update the display as often - the SLOW and FAST commands determine the video display rate. The FAST command allows the program to run 4X faster, but then the display gets jerky.
Other models:
Timex Sinclair 1000, 1982, sold by Timex in USA
Timex Sinclair 1500, 1983, sold by Timex in USA, stop-gap between the TS 1000 and the forthcoming American version of the Spectrum, the TS 2000 (never released). It was a ZX81 with an internally housed 16K RAM expansion module, in a black and silver Spectrum-style box with the familiar "dead flesh" rubber keyboard. The updating of the ZX81 design was an attempt to counter the two biggest drawbacks of the TS 1000, namely the touch-sensitive keyboard and the minuscule 1K of memory. The machine failed dismally: no matter how much it was dressed up, it was still a ZX81, with most of that machine's limitations still intact.




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