hp proprietary uP history (9825 uP?)

From: Tony Duell <ard_at_p850ug1.demon.co.uk>
Date: Tue May 4 18:17:59 2004

> >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

Yes. You get the pin header on the PCB (with a loopback test connector
normally). You have to remove that loopback conenctor and plug in the
cable. It's a standard 0.1" pitch header, so the mating connector is
trivial to find.

> 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.

If you have anything apart from the user-terminated one and the 085
floppy one, can you buzz out the connections and note down which links
are fitted, please. I assume you have the 98032 user manual which
explains the connections and links.

Received on Tue May 04 2004 - 18:17:59 BST

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