A free Instructor 50 emulator for the command line.
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A free Instructor 50 emulator for the command line.


clinstructor should so far work both under Mac OSX (tested on 10.8) and GNU/Linux (tested on a recent Arch Linux installation) with the usual present C compilers (Apple's clang or GNU's GCC) and the respective standard libraries. Normally, nothing more than just invoking make in this directory should be necessary to leave you with the executable. Thanks to Nils Eilers, Microsoft Windows is now supported via cross compilation using MXE, but you can also use a far more mature emulation software for even more 2650-based hardware called WinArcadia by James Jacobs.


You can run the program from the command line with the following syntax:


INPUT-FILE is a usual text file with the Signetics 2650 machine instructions in ASCII (or compatible) hex characters (0--9, A--F). Whitespace gets skipped and, from every two characters one 8-bit instruction or data byte is formed. You find some example code in the examples/ folder.

MEMORY-START-ADDRESS is an optional parameter that is only used for the command line debugging interface that currently shows the contents of 256 adjacent bytes from the emulated memory. With this parameter you can specify the start address of the displayed memory page.

Usage Note

Currently, this is pure alpha software---or even less. There is nothing more inside than a basic Signetics 2650 emulation loop with 32 kB of emulated memory. No interrupts, no other I/O operations. And don't expect correct timing. It will just run as fast as your machine is able to execute my non-optimized first attempt to program in C. It will, however, show you how fast this was compared to a real 2650 running at a clock speed of ~895 kHz.

Nevertheless, I welcome any feedback on this code. Test it and send me bug reports or fork it, improve it, and send me pull requests! Perhaps/hopefully, this will once become a useful emulation software for this old system...