I'm considering doing a little more work on Ice-T. Trouble is, I'm out of memory. The only remaining unused memory is that under the OS ROM and I'd like to make use of it. Why did I never use it before, you are surely asking? The reasons are several:
- I didn't need it. XE banked memory provided far more than what was necessary and was the easiest to use.
- I didn't know how to do it without instantly crashing the system.
- Even if I did it, I wouldn't know what areas in memory would be safe to use without breaking disk, printer and serial port I/O, all of which must remain available. The OS VBI routine needs to keep running, the keyboard interrupts need to be serviced as usual. There are also probably a few things I've forgotten or that I'm not even aware of that need to keep working.
- Some working environments (various DOSes, custom OSes, etc) themselves use the XL memory for their own purposes, making questions 2 and 3 even harder to answer. I also need to worry about not breaking them.
Well, issue 1 is no longer correct. For issue 2 I could probably do some research and figure it out (I'd still appreciate getting the answer here), but 3 and 4 have me stumped.
Of course if these issues have been discussed elsewhere I'd love a link. Cheers