25 Jan
2011
25 Jan
'11
1:50 p.m.
On 25/01/11 19:23, Tony Duell wrote:
I have a sneaking suspicion it's a 4-layer board...
Hae you looked for activity on the bus lines,
processor pins, SIMM
sockets, etc? It may be soemthing obvious.
Not yet. If I get sufficiently bored in the not too distant future, I'll
probably build up an ISA bodge-board for the HP16500B and see what's
going on.
I susepct that this is the crystal for the OSC pin on
the ISA bus and
nothing more. It's used as a colour subcarrier master clock by CGA cards,
as master clock for soem other boards that can use an odd frequency
like that and very little else.
Fair enough.
I have a
sneaking suspicion the through-plating on the RTC socket might
have gone iffy (I'll be breaking the plastic alignment bands on the
socket and soldering the top-side tomorrow) but on the off-chance this
I asusme ther are internal signal layers too, so resoldering both
surfaces may not be enough. A rater OT question ; Can uou buy new, at any price, a
PC motherboard tht
will take ISA cards? Ive got a lot of number of special-purpose ISA cards I
have, and seen even more, but I guess if you want to use things like that
you have to keep an old machine running.
You can get PICMG-compliant single-board computers which will take an
ISA riser card. I've got one kicking around somewhere... if memory
serves it's an AAEON SBC-675 Socket370 Celeron board. Nice little thing,
essentially a full computer on a full-length board. About the same size
as a Western Digital WD1003 Winchester controller card actually.
--
Phil.
classiccmp at philpem.me.uk
http://www.philpem.me.uk/