Changes

|successor = [[ZX Spectrum emulatorsline|ZX Spectrum]]

The '''[[wikipedia:ZX81|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 {{Inflation|USD|99.95| 1981}}. 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 emulatorsline|ZX Spectrum]] and was hugely successful, and more than 1.5 million units were sold before it was discontinued.

! scope="col"|Operating SystemPlatform(s)

! scope="col"|[[libretro|Libretro Core]]! scope="col"|Relative Speed<ref group=N name=RelativeSpeed>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.</ref>! scope="col"|<abbr title="Free/Libre and Open-Source Software">FLOSS</abbr>

! scope="col"|Relative Speed<ref group[[Recommended emulators|Recommended]]|-! colspan=N name"8"|PC / x86|-| [[Clock Signal|CLK]]| align=RelativeSpeed>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 frameleft|{{Icon|Linux|macOS|FreeBSD}}| [https://github. com/TomHarte/CLK/releases {{clkVer}}]| {{✗}}| 100.0% denotes the same execution speed as a real machine| {{✓}}| {{✓}}| {{✓}}|-| [[ZEsarUX]]| align=left|{{Icon|Windows|Linux|macOS|FreeBSD}}| [https://github.<com/chernandezba/zesarux/ref>releases {{ZEsarUXVer}}]| {{✗}}| 110.9%| {{✓}}| {{✓}}| {{✓}}|-! scope="col"|[[Recommended EmulatorsEightyOne]]| align=left|{{Icon|Windows}}|Recommended][https://sourceforge.net/projects/eightyone-sinclair-emulator/files/ {{EightyOneVer}}]| {{✓}}| 114.3%| {{✓}}| {{✓}}| {{✓}}

|[[Clock SignalSpud81| align=left|CLK]]{{Icon|macOS and UNIXalikesWindows}}|[https://github1drv.comms/TomHarteu/CLK/releases s!Ar4VkKtk_3JzgQFkPzv4WgWTMHNc?e=trhIHh 0.221]| {{clkver✗}}]| 114.9%|{{✗}}|{{✓✗}}|100.0%|{{✓~}}

|[https://sourceforge.net/projects/sz81/ SZ81] <br/><small>(xz80 & z81 based)</small>|UNIX, align=left|{{Icon|Windows, [[Amiga emulators|Amiga]]<br />Linux, |macOS|FreeBSD|AmigaOS}}|[http://sz81.sourceforge.net/#downloads 2.1.7] <br/>[http://rullf2.xs4all.nl/sz81/ 2.3.910 (Unofficial)]|{{✗}}| 100.0%|{{✗✓}}|100.0%{{✗}}|{{✓~}}

|[[ZEsarUXMAME]]|Multi-platformalign=left|{{Icon|Windows|Linux|macOS|FreeBSD}}|[httpshttp://githubwww.mamedev.comorg/chernandezba/zesarux/releases release.html {{ZEsarUXVerMAMEVer}}]|{{✗✓}}| Not tested|{{✓}}|110.9%{{✓}}|{{~✗}}

|[[EightyOne]http://zxplanet.emuunlim.com/mme-review.htm MTMW]<br/><small>(aka 'MulTiMachine')</small>| align=left|{{Icon|Windows}}|[https://sourceforgewww.zophar.net/projectssinclair/eightyonemulti-sinclair-emulator/files/ machine.html 1.30b]| {{EightyOneVer✗}}]| Not tested|{{✓✗}}|{{✓✗}}|114.3%|{{~✗}}

|[[No$|No$ZX]]| align=left|{{Icon|Windows, |DOS}}|[http://problemkaputt.de/zx.htm 2.0]|{{✗}}|{{✗}}|100.1% <br/><ref group=N name=NoCashSpeed>After turning off the simulated hardware improvements that were not standard in the original computer.</ref>|{{~✗}}| {{✗}}| {{✗}}

|[[MAME]http://zx81.vb81.free.fr VB81 XuR]|Multi-platformalign=left|{{Icon|Windows}}|[http://wwwzx81.vb81.mamedevfree.orgfr/download/releaseVB81_XuR_EXE.html zip 21/05/2022]| {{MAMEVer✗}}]| 100.5%|{{✓}}|{{✓}}|Not tested|{{✗}}

|[http://zxplanetfreestuff.emuunlimgrok.com/mme-reviewco.htm MTMW] <bruk/><small>(aka 'MulTiMachine')<vb81/small>VB81]| align=left|{{Icon|Windows}}|[httpshttp://wwwzx81.zopharvb81.netfree.fr/vb81/sinclairdownload/multivb81-machinefull.html exe 1.30b30]|{{✗}}| Not tested|{{✗✓}}|Not tested{{✗}}|{{✗}}

|[http://zxplanet.emuunlim.com/xtender-review.htm XTender2]| align=left|{{Icon|DOS}}|[http://www.zx81.nl/ beta 13]|{{✗}}| Not tested|{{✗}}|Not tested{{✗}}|{{✗}}

|[http://www.retroisle.com/sinclair/zx81/emulators.php ZX81 Emulator] <br/><small>(Paul Robson)</small>| align=left|{{Icon|DOS}}|[http://www.zx81.nl/ 4.00]|{{✗}}| 101.5%|{{✗}}|Not tested{{✗}}|{{✗}}

! colspan="78"|Mobile/ ARM

|[https://sourceforge.net/projects/sz81/ SZ81] <br/><small>(xz80 & z81 based)</small>|[[wikipedia:Sharp align=left|{{Icon|Zaurus|Sharp Zaurus]], <br/>GPH GP2X/Dingoo|Wiz, <br/>Dingoo A320}}|[http://sz81.sourceforge.net/#downloads 2.1.7]|{{✗}}| 100.0%|{{✗✓}}|100.0%{{✗}}|{{✗}}

|[https://zx81-ios.weebly.com ZX81 iOS]|[[IOS emulatorsalign=left|{{Icon|iOS]], <br/>Devices with METAL framework support }}|[https://itunes.apple.com/us/app/zx81/id1180117434?mt=8 1.511.21]|{{✗}}|{{✓}}|100.61% <br/><ref group=N name=ZX81iOSSpeed>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.</ref>| ?| {{✓}}|{{~}} <br/><ref group=N name=ZX81iOSNeutered>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.</ref>