RDROYA01@ULKYVX.BITNET.UUCP (05/15/86)
There are two related questions I have about CP/M. Using CP/M-68K, I have
been working on a way to call the CCP from within a program, a trivial
task. I have it set up to do any built-in service, but if I, mistakenly,
ask it to run a program, then I cause a priviledge violation and my program
aborts. I would like to set up an exception handler that traps priviledge
violations and returns control to my program. Ideally, the CCP should just
service the built-in calls and the exception handler should recover from
the error caused by trying to invoke a transient utility. At this point,
I'm not really interested in being able to load other programs in memory
but simply avoid the abort caused by the exception. My question is
How do I use the C language signal() function to do this?
I would rather use the C function primarily because it is supposed to
preserve all the registers and keep up with the sloppiness. Assembly
language would probably be better, but I cannot live without ambiguity. I
have had problems using the BDOS set exception vector. The trap #0 and
trap #1 instructions that are supposed to stay memory resident through a
"warm start" do not stay resident. They are reset as soon as a program
exits. This is a real problem for setting up RSXs and running more than one
application at a time.