>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, looks like you are absolutely right, this would be a garden variety digital clock chip! Looking at the schematics, U15: https://drive.google.com/open?id=1kNq0-IUBcPKDAE8k4Ztg2eoUCWHPr4hI The outputs Sa-Sg are standard names for 7-segments, and are read on the processor bus. They don't bother to read segment d, I suppose they can differentiate all the numbers without reading that one. DI must be the Decimal Indicate segment. D1-D3 would be the digit counter. C25, READ and SET are the inputs - we'd have to find what they exactly do. Would they then set the clock by just toggling the digits in one by one as one would do to reset a clock? Anyhow, it seems I could set the Sa-Sg signal to test pattern and see if indeed I read digits different than 8, and confirm that everything is working but the clock chip. Now, how to find a more or less equivalent replacement chip. Marc
-----Original Message----- From: Tony Duell [mailto:[email protected]] Sent: Thursday, June 06, 2019 8:25 PM To: CuriousMarc; General Discussion: On-Topic and Off-Topic Posts Subject: Re: HP98035 Real Time clock and AC5954N clock chip On Thu, Jun 6, 2019 at 8:57 PM CuriousMarc via cctalk <[email protected]> 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
