amiga-news.de - Amiga emulator with analysis features: Jammy for Windows and Linux

30.Mar.2026

Amiga emulator with analysis features: Jammy for Windows and Linux
Jim Shaw has been a programmer for many years and, after buying an Amiga in 1990, wrote a few commercial games for the Amiga during his "first real job". He started his Amiga emulator project in December 2020 during lockdown. His motivation was, and still is, to understand what's going on. He explains to us:

"To do this, I had to write my own emulator - it isn't based on UAE, but is completely new and coded in C#. I quickly realised that while the Amiga is quite simple, it's also a difficult machine to emulate well. So I've spent a lot of time getting the emulation right and haven't entirely succeeded, but have enjoyed trying. It runs a lot of games and tech demos very well, including those which require near-cycle exact emulation.

Jammy-Einstellungen

But the things that make Jammy unique are that it can run all kinds of tracing while programs are running, so it can track OS calls and determine subroutines and loops, determine which memory is being used as code and/or data, and produce a disassembly. That disassembly can be edited in a text editor then re-loaded into the emulator as the starting point for another run. It can also use Graphviz to give a graphical flow diagram for the code path being executed. All of this is work in progress, I'd rather use a database than text files, but haven't got round to all that yet. It has a nice graphical debugger that can single-step through the code and inspect many of the machine's internals."

The separate debugger window (shown here superimposed over the main emulation window in the screenshot) allows you to control the processes described above: you can inspect many of the internals, start and stop and single step the emulation, change disk, trigger interrupts. The little black box lets you type commands to set breakpoints etc.

The third separate window is the console window, which displays a log of interesting events taking place inside the Amiga. This can also be useful for troubleshooting.

As he is also a tech enthusiast, he enjoys experimenting with new things. That is why he created an X11 and Wayland driver to make the emulator run on Linux. Currently the Linux version does not work well at all under wayland, only X11. As the emulator is written in C#, it should run without any problems on ARM PCs.

There are essentially three different options to choose from:

Native: written by the author himself
Musashi: Motorola 680x0 emulator by Karl Stenerud
Moira: 68000 emulation by Dirk W. Hoffmann

The developer emphasises that his project is not intended to compete with WinUAE and "a lot of stuff doesn't work quite right and that it is likely to stay that way. It's really an Amiga internals analysis tool and it's still early days for that part being useful."

The current version is alpha version 19. (dr)

[News message: 30. Mar. 2026, 18:12] [Comments: 0]
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