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"|[[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=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"|[[Recommended Emulatorsemulators|Recommended]]

! colspan="78"|PC / x86

|[[Clock Signal|CLK]]|align=left|{{Icon|Linux|macOS|FreeBSD}}|[https://github.com/TomHarte/CLK/releases {{clkverclkVer}}]|{{✗}}| 100.0%|{{✓}}|100.0%{{✓}}|{{✓}}

|[[ZEsarUX]]|align=left|{{Icon|Windows|Linux|macOS|FreeBSD}}|[https://github.com/chernandezba/zesarux/releases {{ZEsarUXVer}}]|{{✗}}| 110.9%|{{✓}}|110.9%{{✓}}|{{✓}}

|[[EightyOne]]|align=left|{{Icon|Windows}}|[https://sourceforge.net/projects/eightyone-sinclair-emulator/files/ {{EightyOneVer}}]|{{✓}}| 114.3%|{{✓}}|114.3%{{✓}}|{{✓}}

|Spud81|align=left|{{Icon|Windows}}|[https://1drv.ms/u/s!Ar4VkKtk_3JzgQFkPzv4WgWTMHNc?e=trhIHh 0.221]|{{✗}}| 114.9%|{{✓✗}}|114.9%{{✗}}|{{✓~}}

|[https://sourceforge.net/projects/sz81/ SZ81] <br/><small>(xz80 & z81 based)</small>|align=left|{{Icon|Windows|Linux|macOS|FreeBSD|AmigaOS}}|[http://sz81.sourceforge.net/#downloads 2.1.7] <br/>[http://rullf2.xs4all.nl/sz81/ 2.3.10 (Unofficial)]|{{✗}}| 100.0%|{{✗✓}}|100.0%{{✗}}|{{~}}

|[[No$|No$ZXMAME]]|align=left|{{Icon|Windows|DOSLinux|macOS|FreeBSD}}|[http://problemkaputtwww.mamedev.deorg/zxrelease.htm 2.0html {{MAMEVer}}]|{{✗✓}}| Not tested|{{✗✓}}|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://zxplanet.emuunlim.com/mme-review.htm MTMW]<br/><small>(aka 'MulTiMachine')</small>|align=left|{{Icon|Windows|Linux|macOS|FreeBSD}}|[httphttps://www.mamedevzophar.orgnet/sinclair/releasemulti-machine.html 1.30b]| {{MAMEVer✗}}]| Not tested|{{✓✗}}|{{✓✗}}|Not tested|{{✗}}

|[http://zxplanet.emuunlim.com/mme-review.htm MTMW[No$|No$ZX]] <br/><small>(aka 'MulTiMachine')</small>|align=left|{{Icon|Windows|DOS}}|[httpshttp://www.zopharproblemkaputt.net/sinclairde/multi-machinezx.html 1htm 2.30b0]|{{✗}}| 100.1% <br/><ref group=N name=NoCashSpeed>After turning off the simulated hardware improvements that were not standard in the original computer.</ref>|{{✗}}|Not tested{{✗}}|{{✗}}

|[http://zxplanetzx81.emuunlimvb81.com/xtender-reviewfree.htm XTender2fr VB81 XuR]|align=left|{{Icon|DOSWindows}}|[http://wwwzx81.zx81vb81.free.fr/download/VB81_XuR_EXE.nlzip 21/ beta 1305/2022]|{{✗}}| 100.5%|{{✗✓}}|Not tested{{✓}}|{{✗}}

|[http://wwwfreestuff.retroislegrok.comco.uk/sinclair/zx81vb81/emulators.php ZX81 EmulatorVB81] <br/><small>(Paul Robson)</small>|align=left|{{Icon|DOSWindows}}|[http://wwwzx81.zx81vb81.free.nlfr/ 4vb81/download/vb81-full.00exe 1.30]|{{✗}}| Not tested|{{✗✓}}|101.5%{{✗}}|{{✗}}

|[http://freestuffzxplanet.grokemuunlim.cocom/xtender-review.uk/vb81/ VB81htm XTender2]|align=left|{{Icon|WindowsDOS}}|[http://www.zx81.vb81.free.fr/vb81/downloadnl/vb81-full.exe 1.30beta 13]|{{✗}}| Not tested|{{✗}}|Not tested{{✗}}|{{✗}}

|[http://zx81www.vb81retroisle.freecom/sinclair/zx81/emulators.fr VB81 XuRphp ZX81 Emulator]<br/><small>(Paul Robson)</small>|align=left|{{Icon|WindowsDOS}}|[http://www.zx81.vb81.free.fr/downloadnl/VB81_XuR_EXE.zip 1.304.3 (26/11/2019)00]|{{✗}}| 101.5%|{{✓✗}}|100.5%{{✗}}|{{✗}}

! colspan="78"|Mobile / ARM

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

|[https://zx81-ios.weebly.com ZX81 iOS]|align=left|{{Icon|iOS}}|[https://itunes.apple.com/us/app/zx81/id1180117434?mt=8 1.811.01]|{{✗}}|{{✓}}|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>