I've ported the Apple-1 built-in monitor program: WozMon.gcl
The original is 254 bytes, my version is $254 bytes . About half of that is for terminal output (character printing). The Apple-1 had dedicated hardware for that... With this, all original Apple-1 firmware has been ported to the Gigatron :-)
Now you can inspect memory locations, write to them and execute code.
Tutorials for the original WozMon, such as this nice one, are applicable as I tried to deviate as little as possible from the original: the differences are essentially cosmetic or slightly improved usability. The Gigatron-specific differences are:
- Welcome message is "*** WozMon" instead of error prompt ('\')
- Can use lowercase as well as uppercase for hex letters
- Delete shows effect on screen, no need for '_' (RUBOUT)
- Always print address at start of line in block examine mode
- Input buffer has the same size as screen width
- Executed code can go back to monitor with RET instruction ($ff)
- Faster screen update, and cursor symbol instead of '@'
- A bit more careful with empty lines