DigiSim

This is an old logic simulator written back in 1986 for the Apple II. It made it possible to play around with simple networks of basic one and two input logic gates. Up to 8 inputs are supported and the simulation is run for 8 clocks. Note: execution is synchronous, that is gate delay is not part of the simulation. Thus, entities such as flip-flops may not run in deterministic fashion, but they will generally resolve as expected.

In 2024, the original source code to the simulator was unearthed and the original programmer decided to fix up the project enough so that it could be rebuilt from source and run. Originally, the program was written for DOS 3.3 but was converted over to ProDOS in the 1.1.0 release.  The source code is available on github and a prebuilt binary can be downloaded here.  There are rudimentary docs for the application in the github readme.

The application is contained in an Apple II '2MG' format 140k disk image file which can be read by most emulators or written to a 5.25" floppy disk and run on a physical device.  It could also be used with tools like Floppy EMU and CFFA to run on physical hardware.  

The source code is a work in progress.  The original assembly had almost no comments and the memory layout was undocumented.  The code is actively being updated to address seme of these limitations.  It is available on github.  Issues being worked on include:

• ProDOS support
• Improved routing and display of wiring between nodes