the Jupiter Ace emulator

Why build an emulator ?

Micro emulations are great educational tools, They are convienet for study, Can have an arrays of additional addons not availiable or practical to the real hardware, They are not rare so can be duplicated infinate times, Take no physical class room space, Don't get hot and burn out, Can't be broken by the students! (hmm well.. actually..) but best of all are far far cheaper than a real micro and associated hardware!

Additionally the nostalgia for all those that remember those classic micros like the ZX Spectrum, Amstrad CPC, Commodore 64, BBC Micro, Jupiter Ace (hmm not so much) well heres your chance to use a free one ( albeit without the yogurt pot case and a hefty price tag) - Enjoy. ZX Spectrum Emulator

What can it do

The original 3k Screen Inc. Backdoor \ Frontdoor memory access, interuppt CRT phosphor beam, Correct Z80 Instruction timing, oscilator @ 3.25mhz, Sound, Load / Save tape files (.wav) to transfer to and from real Ace.
Its pretty much a complete Jupiter Ace + Cassette Deck, but theres more...

Additional Addons:
Ram Packs, Official 16k, 32k(16k Pacer + 16k daughterboard : stone chip), Official 48k
Load and Save memory snap shots
Keyboard Buffer
Text to Forth (text file input key simulation)
Built in Z80 Assembler
Extensive real time Debugger ( Vars, Flags, OPs, Breakpoints, Interuppt, Tstates timing and more)

More Addons on the way...

For more up to date info check the History column on this page or just download the emulator and see for yourself.

We've written forth, machine code, loaded programs, ironed out bugs, all is well, Even with months of testing we may not find them all .. that's where you feed back any bugs you may have found.

What can't it do

At the present, 4000 ( if indeed there are differencies to emualte:TBC), Additional addons, Color...
Ok so we don't have the room on the net to answer this one...

We are still adding functionallity and other related software projects... work, work, work...

Installation ( NO install, NO registry garbage, NO DirectX, NO Mess )

1) Download the JupiterAce.zipDownload Latest Version 1.0.4247 Build: 37209

2) Unzip the contents to a folder of your choice and run the 'JupiterAce.exe'
and away you go!


NO uninstall required, Just delete the files and its gone.


How to use the emulator ?

TV Screen
ZX Spectrum Emulator
  A - Main Jupiter Ace TV Screen
  B - Minimise Emulator
  C - Change TV Size
  D - Close Emulator
  E - Show Pop-up Menu
  F - Show Tape Deck Window
  G - Mute Ace Sound
  H - Turbo Mode on/off
  I - Pause Ace


Tape Deck
Spectrum Cassette Tape Deck Emulator    
  K - Minimise Tape Ace Tape Deck
  L - Current Cassette Information
  M - Progress of Current Block
  N - Bytes/time Remaining on Tape
  O - Record
  P - Play Tape
  Q - Pause
  R - Previous Block (Rewind)
  S - Next Block (Fast Forward)
  T - Rewind Tape To Start
  U - Eject Tape / Load New Tape


Loading a Game or Program

The simple Way
SnapShot file:
Drag and drop your snapshot file on the TV screen and the emulator will do the rest!!!

Tape .wav file
Although you can still follow the method below there's a much quicker way to load tapes
Type load [name of your program] then drag the .wav file on to the TV screen and the emulator will do the rest.

For example: If the program you are trying to load is called FU then you would type:

load FU

and then drag and drop the correct tape (.wav) file on to the TV screen.

Traditional method using the tape deck

To get started first press button at F on the TV screen and the tape deck window will appear.

On here press the button at U and the browse window will open to allow you to select your tape or snapshot file you want to open.

If you select a .wav file then go to the TV Screen and type:  load [name of your program] as above and then press P on the Tape deck screen to start the tape playing.


If you have any Jupiter Ace, Hardware, Software, Documentation, Information, Stories to tell, Can remember the Cantab Company, You worked there! then please get invlolved and contact us



Microsoft Windows XP, Vista, Windows 7 Possibly others (let us know)
Microsoft .net framework (Vista and Windows 7 have this built in)

If you like our the site, emulator or any of the tools efforts, or just the Jupiter Ace then please link to us, help us climb the Google

Thanks for reading, please if you can help out do so - Enjoy this micro emulator

Key Points


Emulator History

Emulator Diary



Added legacy ".ace" file support to load old snapshots.
Finally, Website & Jupiter Ace Emulator go live!

Website created.

Code debugging, Preperation for public release.

Feb - May
After plenty of set backs 2 non working Jupiter Aces!
We are now up & running back on track!

Jupiter Ace Fixed: Faulty Tri-state Hex Gate
Read about it here...

Started Jupiter Ace Emulator.
See the Videos here plus more info here.

Working core of z80 and Jupiter Ace rom.
Memory and screen memory to windows.
Drag & Drop Loading.
Loading file support, snapshot, Forth to Text.
Microsoft Windows 7 compatible.

How Does it work
Want more info ? Information

we need your help!

Jupiter Ace Cassette Database

In order to maximise the database we need to find as many cassettes as possible, from unknown ones to ones known but we are unable to locate.

If you can help us with any old cassettes you may have in the loft you no longer want or know someone that has then please contact us and give them to a good home, If we can't get there in person we can get them collected by courier - please don't throw them!

Help by donating

Don't worry if you have no old hardware or software to donate, We greatfully accept funds via paypal to help us secure bits from others.

A big "THANK YOU!" to everyone the has donated, time, money, knowledge, tapes and hardware we are truly grateful - micro emulator .net Team.

micro emulator

Free Jupiter Ace Emulator for Windows

It emulates all known Jupiter Ace behaviour, Inc. Z80 (doc'd and undoc'd), Screen, Memory access, Ram packs, Audio tape files, Tape deck emulation, Sound, Forth, Snapshot saving and loading and more ...

The Jupiter Ace emulator is an attempt to preserve this old micro for all to enjoy.


Microsoft Windows 7, Vista, XP
( XP requires microsoft .net framework )

NO install required, and NO registry garbage.

Download the
Latest Version 1.0.4247 Build: 37209 (5466)