4 May
2004
4 May
'04
11:17 a.m.
>Incidentally, the 9845 has one bit of bad design,
IMHO. It's not trivial
[...]
I agree that it could have been better. The 9845s
are very unreliable.
I'm having to constantly reove, clean and reseat the cards in order to keep
them working.
They shouldn't be any worse than any other HP machine unless they've been
stored badly and the connectors have not been properly cleaned. They use
much the same edge conenctors as everything else.
All the clocks
have the connector and logic for the external interface,
it's just a cable you have to add.
IIRC the main circuit board has a connector but IIRC you have to add the
mating connector along with the cable. However I've been lucky and found a fair number of modules with the cables already
installed. However I think
None of mine came with cables, but that was soon cured :-)
[The watch chip ans the microcontroller]
That's interesting. I hadn't looked that
close at the workings of the
time module and had no idea that it was built that way. I wonder why it
included all of that?
Prsumably they needed the functionallity of the microcontroller when the
machine was powered up for things like triggering external events,
responding to the inputs, etc. But the micorcontroller, ROM, etc took too
much power to be battery-backed so they had to add a lower-power clock
for when the machine was turend off. A watch chip, suitably repackaged
(it's in a 24 pin DIP IIRC) was the obvious choice at the time.
electrolyte
less so (but they can generally be repaired). 16 bit parallel
interfaces are really common, but the versions with particular I/O
cables, other thnn the Option 085 one for the 8" floppy are much rarer. I
am still looking for wire- and jumper- lists for all the optional cables.
So am I. I think I have one or two of them but that's all.