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itaych

Member Since 4 Oct 2007
OFFLINE Last Active Jul 22 2018 11:52 AM

Topics I've Started

Using XL memory without breaking stuff?

Fri Jul 20, 2018 2:11 AM

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:

  1. I didn't need it. XE banked memory provided far more than what was necessary and was the easiest to use.
  2. I didn't know how to do it without instantly crashing the system.
  3. 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.
  4. 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 :)