Date   : Tue, 26 Feb 2008 15:42:40 +0000 (WET)
From   : PCOGHLAN@... (Peter Coghlan)
Subject: BBC FPGA Boots to BASIC... almost...

I know its bad form to follow up on my own posting but...

>
>Getting back to BRK, it has always been clear when the B flag is set but it
>I don't think I have ever found out when exactly it is cleared. I assume it
>gets cleared when there is an IRQ? If this is not happening correctly, the
>IRQ service routine would never get called and perhaps IRQs might pile up
>causing interesting effects?
>

What I meant to say is if a BRK is executed setting the B flag, maybe it
never gets cleared again and things fall apart some number of IRQs later?

>
>Finally, is it possible that something suddenly causes NMI to be asserted and
>sends the emulated CPU into a loop trying to service it? Putting some code at
>&D00 to catch it might allow this to be tested.
>

Thats a silly idea! If there are continuous NMIs, nothing useful is going to
get executed before the next one comes along! Looks like a different way would
need to be found to check this if it is suspected.

Regards,
Peter.