[net.micro.68k] 68k asswmbler question

tre@sdcarl.UUCP (05/13/86)

I am using a 68000 based SBC for the VMEbus to debug prototype hardware for 
this bus.  To debug the interrupting capablilities of my hardware, I need
to stop the 68000 and wait for an interrupt (level=4).

This works:
0010AC		MOVE 	#2300,SR
0010B0		JMP	$10B0

This doesn't:
0010AC		STOP #2300

Now according to my book, STOP stops the 68k from fetching and executing 
instructions, until an exception comes along.  If an interrupt request occurs, 
with a high enough level, an interrupt exception occurs.

So, as far I can tell, both examples of code should have the same result.
What am I doing wrong??

-- 
	thomas r. erbe
	{ucbvax,ihnp4,akgua,hplabs,sdcsvax}!sdcarl!tre

rfm@frog.UUCP (Bob Mabee, Software) (05/14/86)

In article <316@sdcarl.UUCP> tre@sdcarl.UUCP writes:
>I am using a 68000 based SBC for the VMEbus to debug prototype hardware.
>This doesn't work:
>0010AC		STOP #2300

The stop instruction causes the 68000 to stop making external memory
references.  Your SBC may be mis-designed and not handle this case.
Since the spin-wait always works, why not just use that?