Computers Overview
Sinclair ZX80
    ZX80 Revisited
    ZX80 vs. ZX81
Sinclair ZX81
BBC Micro
Commodore 64
Sinclair ZXSpectrum
Memotech MTX
Memotech CP/M
Atari ST
Commodore Amiga
DEC 3000 AXP
Raspberry Pi



The Sinclair ZX80 / ZX81

ZX80 & ZX81 Comparison

The ZX80 was very quickly followed by the ZX81, as the specifications show, there was very little technical difference between the two computers, the most significant difference was in the construction. Whereas the ZX80 was built using discrete components, the ZX81 features a Ferranti uncommitted logic array (ULA) chip - allowing the functions of many individual logic ICs to be integrated into a single component. This significantly reduced the chip count from 21 to 4 and allowed Sinclair to greatly reduce the price of the ZX81 compared to the ZX80.

This is well illustrated by this photo comparison between the two PCBs

Photo courtesy of Tynemouth Software

Check out Dave Curran's conversion of a ZX81 to a USB keyboard !






Launch price (kit / built)

79.95 / 99.95

49.95 / 69.95

Processor  Zilog Z80A (or NEC 780-C a Z80A clone)  Zilog Z80A
Clock Speed  3.25 MHz  3.25 MHz
ROM  4 KBytes  8 KBytes
RAM - fitted  1 KBytes  1 KBytes
RAM - maximum  16 KBytes (external expansion)

 64 KBytes (external expansion)

 56KBytes useable

Display  24 lines of 32 characters per line
Colours  Monochrome
Sound  None
I/O Capability  Z80 Bus, RF Out (TV), Cassette Interface
Data Storage  Cassette Tape
Built in language

 Sinclair BASIC

See how Sinclair BASIC compared against competitor machines of the time when running PCW Benchmark tests here.


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