WOZ monitor on TTL

TV Typewriter is just a stepping stone and by now we also have a small monitor program. To stay in retro style, this time we didn’t invent our own but we faithfully ported the Apple-1 built-in monitor program to the TTL architecture: the infamous Woz Monitor!

Now you can directly inspect memory locations, write to them and execute code on the hardware itself.

Steve Wozniak’s original is 254 bytes, our version is $254 bytes. About half of that is for terminal output, or character printing. The Apple-1 had dedicated hardware for that, something we’d consider cheating of course [tongue in cheek].

Source and GT1 object files are available in GitHub. A nice user manual for the original is here. With this step, all original Apple-1 firmware has been ported to the Gigatron 🙂