hp proprietary uP history (9825 uP?)

From: Joe R. <rigdonj_at_cfl.rr.com>
Date: Tue May 4 08:16:07 2004

At 04:09 AM 5/4/04 +0100, you wrote:
>> >> There are unless you got the optional Hi-Performace bit-slice CPU. One
>> >
>> >I think I may well have that.
>> That would be cool! I have four or five 9845s but I don't think any of
>> mine have that option.
>What do you have in the far right slot? Is it a single PCB with an HP
>metal-heatsinked hybrid on it, a set of 3 boards, or what?

  I can't tell you at the moment. Mine are all in storage. I sort of lost
interest in them. They're a PITA to keep working and take up too much room.
If anybody wants one come and get it. I have several and I don't think I'm
going to bother with them any more. I will not ship!!! These are big, heavy
and awkward!

>Incidentally, the 9845 has one bit of bad design, IMHO. It's not trivial
>to dismantle. To take off the top cover you have to remove the 2 little
>metal latch brackets for the montior first. And you have to remove the
>keyboard/tape drive assembly to get the cards out, they just don't clear
>the back edge of it when the keyboard is screwed down. Oh well...

   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.

>> >I know little of the history of my 9845, other than when I got it it came
>> >with 2 8" drives, a few 16 bit parallel interfaces, 3 HPIB interfaces
>> >(!) a real time clock at least one RS232 interface and the rather
>> >hard-to-find 9878 expansion chassis.
>> hard to find? Sheesh I find them all over. nearly every 9825 that I find
>They're not at all common in the UK...
>> comes with one. I just passed one up in a scrap yard a couple of weeks ago.
>> Also passed up a couple of the RTC modules. The RTC modules with the IO
>> cable are cool. You can interface them to external devices and trigger the
>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
they're all new. I don't think I've ever found one that had been wired up
to anything.

>> devices or use the device to trigger events in the 9845.
>That clock is one strange design. When the machine is powered up, the
>clock is done in software on the HP microcontroller inside. But there's
>also a digital watch chip (!) which is battery backed and used to keep
>the time when the machine is powered down.
>The interface to the watch chip is what you might expect. a couple of
>'buttons' for things like selecting the time/date, setting the clock,
>etc, digit strobes (outputs from the watch chip) and the 7-segment
>outputs (one of which isn't used, since the microcontroller can identify
>the digit without it). I think there's also an annunciator output, which
>means there are only 3 digit strobes (the most significant digit is
>either blank or 1, both for time and US-style date, so you just need a
>single line for it, rather than a complete digit.) You can actually
>attach a 7 segment display to traces on the board and get it to display
>the time when the clock module is starting up.

  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?

>Incidentally, the clock testpoint mentioned in the manual is one of the
>digit strobes. That's why it's a division of 3 from a power-of-2
>frequency. And that's what 'gave it away' when I was sorting out just
>what was going on on that board.
>The clocks are fairly common, ones that have not been damaged by battery
>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.

>Have you seen a metal-cased I/O module for these machines? One of my HPIB
>interfaces is in a die-cast case, not a plastic one.

  Yes I've seen several of those. I've heard of something called "Tin-roof"
or somesuch and it think it referred to those. I think it was a change to
make them comply with some new RFI emissions requirements. I had some
messages that referred to it but I lost them when my HD crashed.


Received on Tue May 04 2004 - 08:16:07 BST

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