Timesharing/multiuser BASIC for MC68K

Joseph Zatarski jzatar2 at illinois.edu
Mon Mar 20 16:20:42 CDT 2017

I just wanted to share a little project I've been working on, it's an
adaptation of Lee Davison's EhBASIC to become a timeshared multiuser BASIC.
There's still a bit more to do, but here's a video of it in operation:

In that video, it's only running 3 sessions (I had no convenient 4th
terminal) but it's capable of running 4. It is a very very simple
preemptive multitasking 'kernel' providing I/O services and performing
periodic context switches for the instances of the interpreter. It only
runs a fixed number of processes, and all the process memory is statically
allocated. EhBASIC lends itself well to this, the code is position
independent by design, and the memory range is passed in. Everything is
dereferenced relative to the 'start of memory' pointer. This means no need
for an MMU or relocation.

I'm hoping to set this up at VCF MW in September, running 4 terminals.

More info on the hardware I'm using is available here:


And another software project I'm working on as well (a ROM monitor program):

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