30 Sep
2005
30 Sep
'05
2:57 p.m.
On 9/30/2005 at 3:24 PM Jules Richardson wrote:
Nope, PC's right up through the PS/2 used NMI (int 2) to diagnose memory parity and
bus errors, as well as 80x87 exceptions. PS/2's also had a watchdog timer that could
be activated (int 15h, ah=C3) to trip if the timer interrupt went un-serviced. The NMI
could be selectively masked, of course (port 61h).
There were a fiew BIOSes out there ("were" is operative, isn't it? No one
actulaly makes new PC's using 30-pin SIMMs.) that would note the lack of the parity
bit and simply mask it at POST time.
I can recall that 30 pin non-parity SIMMs were specifically called out by some retailers
as being for "Macintosh only).
Cheers,
Chuck
I beliee that
most PCs could make use of the added parity bit, while
Macs didn't care if it was present.
(ignoring attributions here I know)
Isn't that the other way around? Nearly all PCs I've come across don't
care about parity, but the rest of the world always seemed to make use
of it.