HP98035 Real Time clock and AC5954N clock chip

[Tony Duell]

On Thu, Jun 6, 2019 at 8:57 PM CuriousMarc via cctalk
<cctalk at classiccmp.org> wrote:
>
> All HP fans in general and Tony in particular,
> I have the exact same problem. HP98035 real time clock module
> (http://hpmuseum.net/display_item.php?hw=168), plugged into a HP9825T
> (http://hpmuseum.net/display_item.php?hw=171), accepts commands, reads back
> all 8's. Battery is new, is charging and at the correct voltage.
> Documentation says "never run the module without the battery or it would
> damage the AC5954N clock chip". When I got the module it had not battery in
> it, so this is what could have happened. Tony, did you eventually repair
> your module or find some data on the clock chip?

I've certainly got a working 98035, but I can't remember if I repaired this one.

The clock chip seems to be a normal digital watch/clock chip. The inputs to
it are essentially the 'set' buttons, the outputs are the 7 segment lines and
digit strobes. But I have not found a data sheet on it anywhere.

-tony