To be clear CP/M once running only used one of the possible 4 ram banks??
I ask as then I don't have to search trough the code to understand if it
does and how.?
?
Reason I ask Is I have a version of a Bios that is banked.? I've developed more
than a few BIOS for different systems most to improve the rather simplistic
support for IO.? That and allow for more disk starting with 5mb in 1980 and
growing from there. ? The result? of a banked BIOSis larger TPA as the BIOS
is less than 2K in high ram but the paged ram contains the rest of the bios
and especially the large buffers used for the allocation vectors.? ?The remaining
two pages (64K total) can be used for RAM disk or foreground/background
programs.? Foreground background is easy to do, periodic interrupt driven
code causes a simple tasker manager to see if a task is pending?and if so
executes it.? Only one task level for simplicity usually print spooler.
Its easily extended to more.? Since its an interrupt driven CP/M doesn't
directly see it as it steels cycles and returns.? If IO such as a circular input
buffer (to support type ahead)? exists and interrupt drive then its the
priority task in the list.
?
Nice system.
?
Most people don't really understand CP/M and really don't realize that?
it is very permissive in what can be done.??
?
?
Allison
