Date   : Fri, 08 Jan 1988 11:06:51 PST
From   : Bridger Mitchell <bridger%rcc@rand-unix.ARPA>
Subject: Debugging an RSX

Most debuggers use the bdos (rather than the bios) for terminal
input/output, so the first thing you have to do is avoid re-entering
the bdos when you are tracing/trapping.

You might try this approach under the debugger:

5:     jmp rsx_entry

100:
program:
       ...
xx:    call 5          ;bdos call at routine causing trouble
       ...

Change the 'call 5' to 'call rsx_entry'.
Set breakpoints at 0000, the program's exit routine, and xx.
Set up command line and execute from 100.  When you hit
the xx trap, set other breakpoints in the rsx at important
spots, then single-step into the rsx to watch things.

You can get symbols for the rsx by assembling it once with origin =
rsx_entry and loading that symbol file under the debugger.  Some
debuggers will cummulate symbols from several files, so you can also
load symbols from the transient program if you have them.

If you do much debugging, you may want to patch the debugger to
use bios i/o.

--bridger