Re: HP98035 Real Time clock and AC5954N clock chip

[Paul Berger via cctalk]

On 2019-06-08 5:40 p.m., Chris Elmquist via cctalk wrote:

On Friday (06/07/2019 at 11:01AM -0700), CuriousMarc via cctalk wrote:

I wondered if it's actually a digtal watch chip (2.5V could have been a couple
of mercury cells in series, LED watches were not uncommon back then).

In which case it would not normally have come in a 0.6" wide DIP. Perhaps
normally it was a bare chip directly mounted on the watch circuit board or
something.

The DIP version would be unusual, which is perhaps why we can't find data
on it.

-tony

I think you are on to something. That would make perfect sense.

FWIW, there was an article in Kilobaud magazine, perhaps 1977 or '78
that described connecting a TI LED digital watch to the SS-30 bus in
the SWTPC 6800.

I built this then, wrecking the TI watch as a watch but it made an
excellent RTC for this machine.  Two AA size NiCADs were used to power
the watch and charged through a simple trickle charge when the machine
was powered up.

The interface to the host was through a 6820 PIA, with just the segment
lines and a couple of output bits.  The output bits indeed "pressed"
the buttons on the watch and the code would set it just like a human
would by stepping through each digit in sequence and "pressing" the
other button to increment that digit.

When reading the clock, the code would pretend to set the watch but never
increment any digit.  It would just press the button to advance to the
next digit, stepping through all of the digit positions until it had
read them all (both time and date) and then return this buffered result.

By pretending to set the clock but not actually changing it, it allowed
the code to know which digit was being displayed and therefore it did not
need to have the digit select lines brought into the host.

Chris


That article "Let Your Computer Wear a Watch" was in the October 1978 
Kilobaud available on archive.org


Paul.

Re: HP98035 Real Time clock and AC5954N clock chip

[Chris Elmquist via cctalk]

On Friday (06/07/2019 at 11:01AM -0700), CuriousMarc via cctalk wrote:
> > 
> > I wondered if it's actually a digtal watch chip (2.5V could have been a 
> > couple
> > of mercury cells in series, LED watches were not uncommon back then).
> > 
> > In which case it would not normally have come in a 0.6" wide DIP. Perhaps
> > normally it was a bare chip directly mounted on the watch circuit board or
> > something.
> > 
> > The DIP version would be unusual, which is perhaps why we can't find data
> > on it.
> > 
> > -tony
> 
> I think you are on to something. That would make perfect sense.

FWIW, there was an article in Kilobaud magazine, perhaps 1977 or '78
that described connecting a TI LED digital watch to the SS-30 bus in
the SWTPC 6800.

I built this then, wrecking the TI watch as a watch but it made an
excellent RTC for this machine.  Two AA size NiCADs were used to power
the watch and charged through a simple trickle charge when the machine
was powered up.

The interface to the host was through a 6820 PIA, with just the segment
lines and a couple of output bits.  The output bits indeed "pressed"
the buttons on the watch and the code would set it just like a human
would by stepping through each digit in sequence and "pressing" the
other button to increment that digit.

When reading the clock, the code would pretend to set the watch but never
increment any digit.  It would just press the button to advance to the
next digit, stepping through all of the digit positions until it had
read them all (both time and date) and then return this buffered result.

By pretending to set the clock but not actually changing it, it allowed
the code to know which digit was being displayed and therefore it did not
need to have the digit select lines brought into the host.

Chris
-- 
Chris Elmquist

RE: HP98035 Real Time clock and AC5954N clock chip

[CuriousMarc via cctalk]

> 
> I wondered if it's actually a digtal watch chip (2.5V could have been a couple
> of mercury cells in series, LED watches were not uncommon back then).
> 
> In which case it would not normally have come in a 0.6" wide DIP. Perhaps
> normally it was a bare chip directly mounted on the watch circuit board or
> something.
> 
> The DIP version would be unusual, which is perhaps why we can't find data
> on it.
> 
> -tony

I think you are on to something. That would make perfect sense.
Marc

Re: HP98035 Real Time clock and AC5954N clock chip

[Tony Duell via cctalk]

On Fri, Jun 7, 2019 at 6:50 PM CuriousMarc  wrote:
>
> >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.
>

I wondered if it's actually a digtal watch chip (2.5V could have been a couple
of mercury cells in series, LED watches were not uncommon back then).

In which case it would not normally have come in a 0.6" wide DIP. Perhaps
normally it was a bare chip directly mounted on the watch circuit board or
something.

The DIP version would be unusual, which is perhaps why we can't find data
on it.

-tony

RE: HP98035 Real Time clock and AC5954N clock chip

[CuriousMarc via cctalk]

>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:ard.p850...@gmail.com] 
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
 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

Re: HP98035 Real Time clock and AC5954N clock chip

[Eric Smith via cctalk]

On Thu, Jun 6, 2019 at 9:57 PM Tony Duell via cctalk 
wrote:

> HP were fond of using NiCds as shunt regulators at that time. The did
> it in many of
> their handheld calculators (HP20 series 'Woodstock', HP30 series
> 'Spice', etc). In
> those it wasn't normally a problem (the calculator electronics drew
> enough current to
> pull the voltage down) except in machines with 'continuous memory'
> (battery backed
> RAM). There, if the machine it turned _off_ the RAM is the only thing
> drawing current
> and it doesn't draw enough to pull the voltage down below the zapping
> level.
>

The should have paralleled the battery with zener with a voltage somewhat
above the normal battery charging voltage but below the abs max rating of
the power supply pins of the chips. They saved maybe ten cents by omitting
that.

Re: HP98035 Real Time clock and AC5954N clock chip

[Tony Duell via cctalk]

On Fri, Jun 7, 2019 at 4:44 AM Curious Marc  wrote:
>
> Thanks, I’ll see if I can find replacements. You can easily see how they get 
> zapped: they are 2.5V chips, the NiCd battery *is* the voltage regulator. 
> Charging circuit is a simple diode connected to 5V via a resistor. Battery 
> dies, goes high impedance, somebody plugs it in to try it out and poof! Clock 
> chip gets zapped by 5V.

HP were fond of using NiCds as shunt regulators at that time. The did
it in many of
their handheld calculators (HP20 series 'Woodstock', HP30 series
'Spice', etc). In
those it wasn't normally a problem (the calculator electronics drew
enough current to
pull the voltage down) except in machines with 'continuous memory'
(battery backed
RAM). There, if the machine it turned _off_ the RAM is the only thing
drawing current
and it doesn't draw enough to pull the voltage down below the zapping level.

-tony

Re: HP98035 Real Time clock and AC5954N clock chip

[Curious Marc via cctalk]

Thanks, I’ll see if I can find replacements. You can easily see how they get 
zapped: they are 2.5V chips, the NiCd battery *is* the voltage regulator. 
Charging circuit is a simple diode connected to 5V via a resistor. Battery 
dies, goes high impedance, somebody plugs it in to try it out and poof! Clock 
chip gets zapped by 5V. 
Marc

> On Jun 6, 2019, at 8:24 PM, Tony Duell  wrote:
> 
> On Thu, Jun 6, 2019 at 8:57 PM CuriousMarc via cctalk
>  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

Re: HP98035 Real Time clock and AC5954N clock chip

[Tony Duell via cctalk]

On Thu, Jun 6, 2019 at 8:57 PM CuriousMarc via cctalk
 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

RE: HP98035 Real Time clock and AC5954N clock chip

[CuriousMarc via cctalk]

Paul,
It will accept the set time command, but this has no effect. An error read 
shows code 16, "real time lost". The clock chip seems dead, nothing happening 
when looking at the test output after sending the test mode request.
Marc

-Original Message-
From: cctalk [mailto:cctalk-boun...@classiccmp.org] On Behalf Of Paul Berger 
via cctalk
Sent: Thursday, June 06, 2019 1:28 PM
To: CuriousMarc via cctalk
Subject: Re: HP98035 Real Time clock and AC5954N clock chip

Are you able to set the date and time on your clock?  I had disconnected 
one end of the diode in the charge circuit and powered the clock from a 
lithium primary cell.  I got all 8s when the battery went dead but when 
it was in that state when I tried to set the date and time any commands 
after that to the clock hung, I suspect because the nano processor got 
hung up trying to set the time.  After changing the battery it 
functioned normally again.

Paul.

On 2019-06-06 4:57 p.m., CuriousMarc via cctalk 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?
> Marc
>   
>   
> List:   classiccmp <https://marc.info/?l=classiccmp=1=2>
> Subject:AC5954N clock chip (I think)
> From:   ard () p850ug1 ! demon ! co ! uk (Tony Duell)
> <https://marc.info/?a=10495709738=1=2>
> Date:   2001-08-26 22:55:32
> <https://marc.info/?l=classiccmp=1=2=200108>
> [Download RAW message
> <https://marc.info/?l=classiccmp=104961357310567=mbox>  or body
> <https://marc.info/?l=classiccmp=104961357310567=raw> ]
>   
> I've got a non-working HP98035 real time clock module (for HP9825, etc)
> on the bench.
>   
> It accepts commands, it sends something back, so I think the bus
> interface and microcontroller are all fine. The problems are :
>   
> The real time reads back as 88:88:88:88:88
>   
> There is no activity on the crystal connected to the AC5954N clock chip
> (or at least I think it's a clock chip). Enabling the oscillator
> testpoint doesn't do a darn thing (well, the control/setting latch U7
> changes state so again the microcontroller is doing something). There is
> no activity on any of the pins on the chip.
>   
> It is getting power (it's not a problem with the NiCd battery).
>   
> I suspect the chip. Has anyone come across it? It may be a common digital
> clock/calendar chip, or at least related to one (if it is HP-custom).
> It doesn't seem to be particularly designed for a microprocessor bus --
> the output may be for direct driving 7-segment displays or maybe a
> multiplexed BCD output to link to a display decoder/driver.
>   
> Thanks in advance for any help.
>   
> -tony
>
>   
>

Re: HP98035 Real Time clock and AC5954N clock chip

[Paul Berger via cctalk]

Are you able to set the date and time on your clock?  I had disconnected 
one end of the diode in the charge circuit and powered the clock from a 
lithium primary cell.  I got all 8s when the battery went dead but when 
it was in that state when I tried to set the date and time any commands 
after that to the clock hung, I suspect because the nano processor got 
hung up trying to set the time.  After changing the battery it 
functioned normally again.


Paul.

On 2019-06-06 4:57 p.m., CuriousMarc via cctalk 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?
Marc
  
  
List:   classiccmp 

Subject:AC5954N clock chip (I think)
From:   ard () p850ug1 ! demon ! co ! uk (Tony Duell)

Date:   2001-08-26 22:55:32

[Download RAW message
  or body
 ]
  
I've got a non-working HP98035 real time clock module (for HP9825, etc)

on the bench.
  
It accepts commands, it sends something back, so I think the bus

interface and microcontroller are all fine. The problems are :
  
The real time reads back as 88:88:88:88:88
  
There is no activity on the crystal connected to the AC5954N clock chip

(or at least I think it's a clock chip). Enabling the oscillator
testpoint doesn't do a darn thing (well, the control/setting latch U7
changes state so again the microcontroller is doing something). There is
no activity on any of the pins on the chip.
  
It is getting power (it's not a problem with the NiCd battery).
  
I suspect the chip. Has anyone come across it? It may be a common digital

clock/calendar chip, or at least related to one (if it is HP-custom).
It doesn't seem to be particularly designed for a microprocessor bus --
the output may be for direct driving 7-segment displays or maybe a
multiplexed BCD output to link to a display decoder/driver.
  
Thanks in advance for any help.
  
-tony


  

HP98035 Real Time clock and AC5954N clock chip

[CuriousMarc via cctalk]

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?
Marc
 
 
List:   classiccmp  
Subject:AC5954N clock chip (I think)
From:   ard () p850ug1 ! demon ! co ! uk (Tony Duell)
 
Date:   2001-08-26 22:55:32
 
[Download RAW message
  or body
 ]
 
I've got a non-working HP98035 real time clock module (for HP9825, etc) 
on the bench.
 
It accepts commands, it sends something back, so I think the bus 
interface and microcontroller are all fine. The problems are : 
 
The real time reads back as 88:88:88:88:88
 
There is no activity on the crystal connected to the AC5954N clock chip 
(or at least I think it's a clock chip). Enabling the oscillator 
testpoint doesn't do a darn thing (well, the control/setting latch U7 
changes state so again the microcontroller is doing something). There is 
no activity on any of the pins on the chip.
 
It is getting power (it's not a problem with the NiCd battery).
 
I suspect the chip. Has anyone come across it? It may be a common digital 
clock/calendar chip, or at least related to one (if it is HP-custom). 
It doesn't seem to be particularly designed for a microprocessor bus -- 
the output may be for direct driving 7-segment displays or maybe a 
multiplexed BCD output to link to a display decoder/driver.
 
Thanks in advance for any help.
 
-tony