On Sep 22, 2006, at 12:16 PM, Don North wrote:
Julian Wolfe wrote:
Okay, it halts with 20 in the octal display. Is
that the address?
I guess I need to take this one step at a time.
On Sep 20, 2006, at 1:39 AM, Don North wrote:
Ok, this means that the halt instruction was at 16(8) and probably
came from the trapcatcher setup at 14(8). You can verify this by
examining location 14(8) and see that is has a 16(8) in it.
I did that and got exactly as expected.
14(8) is the vector for the BPT instruction. Now you need to examine
the SP and look on the stack at (SP) to find the saved PC of where
the actual trap occurred. This should be back somewhere in the program
code (if you are lucky). It could be you are unlucky :-(, your CPU
went
wild and just happened to run across an instruction word with an
opcode of 000003 (which is BPT).
Examining the SP gives me a value of 470(8) on the display. Now, from
what I understand, I should be looking for this address in the
listing, correct?
Here is where I have difficulty; it seems to jump from 342(8) to 500
(8) in the instruction listing. Did my CPU go nuts, or am I just
interpreting this wrong?
I am referring to the gap between lines 107 and 112 on page 5 of the
bitsavers copy of the instruction listing.
Thanks again for your help.