11/34 failing trap test

Pete Turnbull pete at dunnington.plus.com
Sat Aug 19 11:37:34 CDT 2006


On Aug 19 2006,  9:38, Wolfe, Julian  wrote:

> I got the 11/34 up and running, and I loaded XXDP.  It fails the trap
> test.  The instructions state you should examine the stack pointer
> (777706) which shows it to be a value of 000470.  This is supposed to
> tell you the address of the Program Counter, right? So I load address
> 470, and the value is 000330.  What instruction is failing?  Am I
> reading this right?

Yes, the stack pointer points to the last address used on the stack,
and that will be the value of the PC when it called the error
subroutine, or to put it another way, the address of the next
instruction to be executed had the JSR not been taken.  It's failing at
whatever test was just before location 330 -- which is surprisingly
low.  You'd need to look at the listing to see what the test was.

-- 
Pete						Peter Turnbull
						Network Manager
						University of York


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