9825A or B ROMs



#9

I recently acquired a 98035 real time extension for the 9825A. It was in a sad state, because everything inside was spoiled by the internal battery that had leaked. I am trying to fix it.
But I ignore how to use it. Does anyone has a doc, or know a command or two that I can use to test this extension ?


#10

Olivier,
I own the 98032A Installation and Operation Manual, but I would have to scan it. And I also have a 98032A interface in the same sad condition. From my experience it is irrepairable, because at least one of the quartz cristals was destroyed by the leaking battery. Try to shake the opened interface. If you hear some faint tinkle, then you propably have the same problem.
Achim


#11

I also have a 98035 in unknown condition, and could use the manual. Is there a chart of the register bit definitions that would be just a few pages to scan? Those charts are usually quite complete in details. I would be happy to pay for the cost to copy the manual.


#12

In my previous posting I made a mistake: I wrote 98032A but I meant 98035A.
And I found the 98035A Installation and Operation Manual on the latest MoHPC CD/DVD. It contains the description of the registers on about 10 pages. The whole manual is about 2MB.


#13

I'm always recommending the CD-ROMs but I didn't know that was on them! Thanks.

Olivier's post made me think about the unit I got a while ago, I opened it up and found some corrosion but not too much.

#14

What freq is the bad crystal? There are many sources of replacement crystals. It is even not to expensive to have a single piece custom frequency made.


#15

The 98035 is one strange design!. There are really 2 clocks in there. One is done in software on the 'nanocontroller' (the 1820-1691 IC), and is used while the machine is powered up. This program also controls the outputs, etc.
There is a separate battery-backed clock used when the machine is powered down. This is in the 24 pin IC on one of the PCBs (not the ROM chip, OK ;-)). THis chip seems to be a digital watch IC, repackaged. The outputs are the drive lines for a 3 digit 7 segment display (with annuciators, that's all you need for a 12 hour display and US date format). The control inputs are essentially the buttons you'd find on an LED watch.
Softwre on the nanocontroller (again) reads/decodes the 7 segment data (I am sure this what the outputs are, I've driven a display from the chip in one of my 98035s...) and simulates 'pressing the buttons' to set/read the clock.
Alas, since it's a 3 digit display, the crystal is not the normal digital watch crystal -- there's a divide-by -3 in the counter chain (the normal watch crystal is 32768 Hz -- divide by 2^15 to get 1Hz).
FWIW, the oscillator testpoint mentioned in the manual is one of the display scan lines (the fact that it's a multiple of 3 Hz, and the fact it's a 2:1 mark-space ratio, is what put me onto the fact tht it's a 3 digit multiplexed display output...)


#16

One component fell of the board when I open the box.
it is a small silver rectangle with 2 pins out but so thin that any attempt to solder new wire to them failed miserably. So it could be the 32768 hz quartz.
If I find such component, do you think that I may have any chance to repair the board ? (I already changed the battery that leaked and cleaned the board and all the gold tracks that were almost blue due to the corrosion brought by the leak).

Olivier


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