Sinclair ZX81 emulators

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Sinclair ZX81
1024px-Sinclair-ZX81.png
Developer Sinclair Research
Type Computers
Generation Z80-based home computers
Release date 1981
Discontinued 1984
Predecessor Sinclair ZX80
Successor ZX Spectrum
Emulated

The ZX81 was a Z80-based home computer produced by Sinclair Research and manufactured in Scotland by Timex Corporation released on March 5, 1981, and had a retail price of $99.95. It had a Z80 at 3.25 MHz with 1KB of RAM.

It was the successor to Sinclair's ZX80 and the predecessor of the ZX Spectrum and was hugely successful, and more than 1.5 million units were sold before it was discontinued. The ZX81 was designed to be small, simple, and above all cheap, using as few components as possible to keep the cost down.

Video output was to a television set rather than a dedicated monitor. Programs and data were loaded and saved onto audio tape cassettes. It had only four silicon chips on board and a mere 1 KB of memory. The machine had no power switch or any moving parts and used a pressure-sensitive membrane keyboard for manual input.

Its distinctive design brought its designer, Rick Dickinson, a Design Council award. The ZX81 could be bought by mail order in kit form or pre-assembled. It was the first cheap mass-market home computer that could be bought from high street stores, led by W.H. Smith and soon many other retailers.

The ZX81 marked the first time that computing in Britain became an activity for the general public, rather than the preserve of businesspeople and electronics hobbyists. 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.

Emulators[edit]

Name Operating System(s) Latest Version Libretro Core Active Relative Speed[N 1] Recommended
PC
CLK macOS and UNIXalikes 2019-03-10 100.0%
ZEsarUX Multi-platform 7.2 110.9%
EightyOne Windows 1.15 114.3%
SZ81
(xz80 & z81 based)
UNIX, Windows, Amiga
Linux, macOS
2.1.7
2.3.10 (Unofficial)
100.0% ~
No$ZX Windows, DOS 2.0 100.1%
[N 2]
~
MAME Multi-platform 0.209 Not tested
MTMW
(aka 'MulTiMachine')
Windows 1.30b Not tested
XTender2 DOS beta 13 Not tested
ZX81 Emulator
(Paul Robson)
DOS 4.00 101.5%
Mobile
SZ81
(xz80 & z81 based)
Sharp Zaurus,
GPH GP2X/Wiz,
Dingoo A320
2.1.7 100.0%
ZX81 iOS iOS,
Devices with METAL framework support
1.5.3 100.6%
[N 3]
~
[N 4]
  1. As calculated by Carlo Delhez's clkfreq, originally distributed with his XTender emulator. The ZX81 has relatively complicated timing mechanics, depending on signalling of WAIT during NMI; relative speed is a measurement of how closely an emulator matches a real machine in terms of clock cycles spent processing within a frame. 100.0% denotes the same execution speed as a real machine.
  2. After turning off the simulated hardware improvements that were not standard in the original computer.
  3. Provided by Kevin Palser the developer (and author of this note) because the app cannot load external programs, such as Carlo Delhez's clkfreq, due to Apple developer restrictions for iOS. Permission to include clkfreq in the app cannot be granted because Dr Delhez sadly passed away in 2015.
  4. This app is neutered as loading of external programs into emulator apps from the App Store is prohibited by Apple. However, it does have a growing selection of programs included with permission granted by their authors.

Notes[edit]

  • www.retroisle.com (Page showing five old emulators for ZX81, and sometimes the Spectrum and other machines)
  • www.worldofspectrum.org's list (Short list of old Science of Cambridge MK-14, ZX80, ZX81 / TS1000, Sinclair QL and Jupiter ACE emulators)
  • zx81.eu5.org (Brazilian ZX81 fan-site - emulators list page is in English. Shows list of old ZX81 emulators & links to other resources.)
  • floppydays.libsyn.com (Podcast episode describing the emulators available for the ZX80 / ZX81 which also uses the Carlo Delhez's clkfreq rating. Also has huge lists of resources for all things ZX80/81 related.)