CP/M on V-Tech Genius Leader 4000: It... works!!!

A project log for V-Tech Genius Leader / PreComputer Hacking

Turning a toy into a hardware tinkering platform

Bernhard Bernhard "HotKey" Slawik 11/05/2019 at 15:260 Comments

This is worth another project log...

Since I got "boot from RAM" working yesterday, I eagerly started implementing the basic BIOS/BDOS functions of CP/M 2.2. No disk access, yet, but just the standard console input/output and housekeeping functions.

Fortunately, CP/M is well documented and there aren't actually that many functions that need to be implemented for a basic system.

So, I fixed my broken LCD DDRAM mapping and optimized the keyboard handler a little and added the most important CP/M BDOS functions.

Then I took a small .COM file (SYSGEN), placed it into RAM and jumped to it...

First CP/M program running on a Genius Leader 4000
Houston, we have a code execution!

I was greeted by the program banner! It works!

That was really unexpectedly simple! The next 1-2 weeks will be used to implement a simple file system and all the necessary open/close/read/write functions, so we all can play ZORK before the year is over! :-)

Stay tuned!