11/34 failing trap test
fireflyst at earthlink.net
Sat Sep 23 04:03:10 CDT 2006
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
> 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
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.
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