IBM System/32 available

Guy Sotomayor ggs at
Mon Nov 9 14:57:21 CST 2015

> On Nov 9, 2015, at 12:26 PM, Eric Smith <spacewar at> wrote:
> On Thu, Nov 5, 2015 at 8:18 PM, Guy Sotomayor <ggs at> wrote:
>> * The expansion bus in the IBM PC was the same bus as the System/23.    The
>> connector was rotated 180* so that some of the less expensive
>>   cards from the PC couldn't be used in the System/23.  The other
>>   reason for this was since the IBM PC was done on a "shoe string"
>>   budget, they could take the System/23 cards and only had to do some
>>   minimal re-layout of the board.
> Did the System/23 also use edge-triggered interrupts, rather than level?


> Do you have any idea why it was thought a good idea to use
> edge-triggered interrupts?

I wasn’t really involved in the HW side of things but I think it was because it was
“easier”.  I think at least one device just generated a pulse for an interrupt rather
than having some sort of latch.

TTFN - Guy

More information about the cctech mailing list