Java Apple Computer Emulator

Apple II Emulator Jace 2012-10-31 released

Brendan Robert has released a new and improved version of his Java Apple II emulator.


] 65c02 CPU emulation is now 100%, tested and verified thanks to Klaus Dormann’s test suite:…nctional_test.a65

] Overall CPU usage is way down thanks to recent changes:
Video generation rolled into main thread and this made things a lot more efficient
Switched to older timer model, newer lock-based timers were considerably slower
Memory listener model streamlined to be more efficient

] Skyfox now detects mockingboard in slot 4
] Pitfall II detects mockingboard and plays perfectly!
] Disk II speedup hack now provided as a configuration option (previously, speedup hacks were always enabled to max the emulator speed when disk is in use)
] Hayes smartmodem now has UI activity indicators

Some folks reported in the past intermittent issues where the emulator would hang on start and never actually begin executing the rom (symptom: Screen with alternating checkerboard and inverse @ symbols). I believe this release fixes that problem once and for all.

This is the most stable and efficient build to date, I hope it is useful to your folks!

Download the latest version here.

Stable version of JACE – Apple II emulator – Released

Java Apple II emulator author Brendan Robert was quite understandably pleased to announce that his JACE emulator has reached a new milestone.

Said Mr. Robert:

This is the first major release, bringing this emulator within a hair of my original vision for what I wanted it to be: it is a complete recreation of the computer I had growing up. (yaaaaaay!) There are a few bugs left to fix, but the only people in this world that claim software is ever complete are sales people. In spite of its flaws it’s ready to get some heavy use: I took the BETA label off the sourceforge page.

# Several timing and deadlock fixes, this not only spells more stable but also a lot more efficient in some cases.

# AE RamFactor card implemented and working. You will need to install the AE Ram Expander for Appleworks to see the extra storage.
*There is an additional option to max out the speed of the emulator when the ramfactor is in use. This means that any applications using Ram for cache or extra storage will speed up dramatically.

# Mockingboard works perfectly with Ultima 5.
*AE Phasor support has been implemented, but it isn’t working right just yet. For now, just use Mockingboard mode.
*Note: Only use ONE mockingboard. Using more than one will cause the timing issues and sound horrible.
*You can use a mockingboard at the same time as a Passport MIDI card. It has a strange syncopated sound to it. it does reveal, however, that the mockingboard playback is pitch-perfect. :-)

# Visual UI completely overhauled: Now fullscreen is possible (press F9)
*Pressing F8 while in fullscreen will toggle aspect-constrained or stretched displays.

# Indicator icons now appear for:
*Disk II activity
*Mass storage activity
*Mouse activation
*SSC activity
*RamFactor activity

Visit the JACE Web site

JACE is free open-source software, licensed under the LGPL. It emulates an Apple IIe with 128K of RAM and an 80 columns card. It supports a disk drive, joysticks, Super Serial Card, AE RamFactor, mass storage, and many other features.

The emulator is compatible with all major computer operating systems.


JACE Emulator Source Code Updated, Build Coming Soon

Brenden Robert has updated his JACE Emulator (Java Apple Computer Emulator) Source code to revision 150 and has said that a new build is coming soon.  The delay in the update was attributed to  several bugs which were preventing a build from being submitted.  According to Brenden’s post on CSA2, “I still have some issues with getting the code to run really well when full-screen, but that’s a video generation/scaling problem and I need to profile the code further to track down what’s going on there to nail it.

Some things fixed are: Video null pointer error on start, Removed program counter from configuration screen to fix crashes when reconfiguring the emulator, better prompts when loading media, and the intro text now correctly indicates the keys for loading disk and hard drive media (was incorrect previously).

Oh, and I fixed the bug that caused sound to not work in games like Moon Patrol (which uses a STA $C030 instead of LDA or BIT) so now sound is pretty much 100% but still kinda choppy if you full-screen. Still, no random crashes or freezes so that’s good.

I would like to have better joystick support but really that’s not going to happen in Java without native libraries, something I’ve been trying desperately to avoid.  Since the configuration system is very modular, it may be possible to have a mod system, similar in fashion to a lot of modern games like Minecraft and the like.  That would allow the base copy of Jace to be dependency-free and allow those who want different emulation options another way.  Come to think of it, I could add an RXTX-based SSC implementation too if needed.”

JACE is primarily being developed by Brenden and Nick Westgate and is one of the few emulators which has Full 128K Support and Double Hi-Resoluition graphics capability.  The features of the JACE Emulator are as follows:

  • Full 128kb support, double-hires and 80-column
  • Disk emulation (dos ordering, NIB)
  • Speaker emulation
  • CPU-saver features (diables sound/video updates when possible)
  • SSC-over-TCP/IP emulation
  • Open-ended design makes it easier for developers to add additional hardware emulation
  • HDV/2MG image support
  • Joystick emulation (using mouse)

While the project began in 2007, the initial release to the public did not occur until January 2011.  For more about the JACE Emulator or to download the source code, go to the website at:

Or you can directly download the source code from the Sourceforge site at: