Real-time clock

[HankG]

I have an old '386 computer that my grandchildren use to run DOS based games
which will not run on my newer computers.

Well, it finally stopped running; would freeze after post. Examination
found that bios information would not be retained. The board does not
contain a battery. There is a Dallas Real Time Clock (1287/1187) chip which
combines CMOS, battery, and clock functions.

These seem to be available and are relatively inexpensive. I would attempt
to replace it (socketed rather than directly soldered).

Information on the chip indicates that they are inactive when received and
must be activated for Intel or Motorola use. I assume that this refers to
the CPU.

My question: what is involved in 'activating' this chip and what
(hardware/software) is required? Thanks.

HankG

 

[Ken]

I have an old '386 computer that my grandchildren use to run DOS based games
which will not run on my newer computers.

Well, it finally stopped running; would freeze after post. Examination
found that bios information would not be retained. The board does not
contain a battery. There is a Dallas Real Time Clock (1287/1187) chip which
combines CMOS, battery, and clock functions.

These seem to be available and are relatively inexpensive. I would attempt
to replace it (socketed rather than directly soldered).

Information on the chip indicates that they are inactive when received and
must be activated for Intel or Motorola use. I assume that this refers to
the CPU.

My question: what is involved in 'activating' this chip and what
(hardware/software) is required? Thanks.

HankG

By "Inactive," I think they mean they are disabled while removed from
the circuit. If there is a jumper to be made in order for it to work,
it is made when it is inserted into your socket. Once that is done, the
battery function of the RTC is connected and ready for its function. At
least all the RTC's I installed required no other action other than
setting them in CMOS setup after being replaced.

 

[HankG]

By "Inactive," I think they mean they are disabled while removed from
the circuit. If there is a jumper to be made in order for it to work,
it is made when it is inserted into your socket. Once that is done, the
battery function of the RTC is connected and ready for its function. At
least all the RTC's I installed required no other action other than
setting them in CMOS setup after being replaced.

It makes sense. The claim of 'inactivity' referenced the battery, to save
life. What about the reference to "Intel or Motorola"?

HankG

 

[C R Briggs]

I have an old '386 computer that my grandchildren use to run DOS based
games
which will not run on my newer computers.

Well, it finally stopped running; would freeze after post. Examination
found that bios information would not be retained. The board does not
contain a battery. There is a Dallas Real Time Clock (1287/1187) chip
which
combines CMOS, battery, and clock functions.

These seem to be available and are relatively inexpensive. I would
attempt
to replace it (socketed rather than directly soldered).

Information on the chip indicates that they are inactive when received and
must be activated for Intel or Motorola use. I assume that this refers to
the CPU.

My question: what is involved in 'activating' this chip and what
(hardware/software) is required? Thanks.

Hank,

You may need to do a bit of research before attempting this repair. There
seems to be more than one type of "Dallas Real Time Clock chip", and some
are not interchangeable.

I had experience with a board which had a "Houston Tech HT12888A" which uses
a VIA VT82885N chip. The VT82885N was meant to be a functional replacement
for the DS12885 but did not meet the correct specifications. One or more
system board manufacturers changed their design to match the specifications
of this device. Therefore, you cannot replace it with a DS12885 chip or
DS12887. For many users this will mean REPLACING the system board because
the HT12888A is not commercially available.

It may be possible to replace the battery on your existing chip - in my own
case I was able to prise off the "plastic block" over the, which revealed
the battery soldered to two of the chip "legs" which had been bent over the
top of the chip.

Good luck,

 

[Ken]

It makes sense. The claim of 'inactivity' referenced the battery, to save
life. What about the reference to "Intel or Motorola"?

HankG

I cannot imagine why there would be any reference to either of them?
My guess is it is just a generic comment to alert the user that CMOS
must be set after the installation.

Ken

 

[HankG]

news:[email protected]...

It may be possible to replace the battery on your existing chip - in my own
case I was able to prise off the "plastic block" over the, which revealed
the battery soldered to two of the chip "legs" which had been bent over the
top of the chip.

Good luck

I would only replace it with a '1287/1187' if I could get one. Think I
might try to pry off the block as you did, since the computer is ancient
(probably late '70s, was made in China, and the documentation (if you want
to call it that) is written in pigeon English.

Could you be specific as to how you removed the block? That is, did you use
something like an X-Acto (hobby) knife to cut around the perimeter, or just
pry with a screw driver? (or whatever). thanks.

HankG

 

[kony]

I would only replace it with a '1287/1187' if I could get one. Think I
might try to pry off the block as you did, since the computer is ancient
(probably late '70s, was made in China, and the documentation (if you want
to call it that) is written in pigeon English.

Could you be specific as to how you removed the block? That is, did you use
something like an X-Acto (hobby) knife to cut around the perimeter, or just
pry with a screw driver? (or whatever). thanks.

I can't guarantee ALL of them are made same way, but "some"
have the top shell with a lip that fits around the base
piece, you might find that if you take something like a pair
of slip-joint pliers and apply compression against the ends
(both shorter sides of the rectangular box) it will make the
middle flex outward some and you can sort-of rotate the
slip-joint pliers sideways flipping up one of the longer
sides. Of course, I make no guarantees it wouldn't be
destroyed, only that it's possible. Be careful about prying
up on it, particularly not pushing away from the board as
that could gouge it- when i find a need to push "something"
away from a board I put down a piece of plastic over the
area, cut out from any scrap I have lying around... a piece
cut out of a margarine lid would be about the same.

 

[C R Briggs]

I would only replace it with a '1287/1187' if I could get one. Think I
might try to pry off the block as you did, since the computer is ancient
(probably late '70s, was made in China, and the documentation (if you want
to call it that) is written in pigeon English.

Could you be specific as to how you removed the block? That is, did you
use
something like an X-Acto (hobby) knife to cut around the perimeter, or
just
pry with a screw driver? (or whatever). thanks.

Hank,

In my experience the situation is similar to that which Kony has already
said.

In my case there was a DIL socket on the motherboard and what is seen
initially is just a "plastic box" closely fitted to a DIL chip. Remove the
complete chip just as you would any other DIL socketed chip.

Two of the chip legs were bent over the top of the chip and connected to a
battery with the "plastic box" just fitted on top. If you find this to the
case with your installation, then DO NOT try to move the bent-over legs as
one or more will almost certainly break off !!

Regards, Good Luck & a Happy New Year to all,

 

[Ralph Mowery]

I would only replace it with a '1287/1187' if I could get one. Think I
might try to pry off the block as you did, since the computer is ancient
(probably late '70s, was made in China, and the documentation (if you want
to call it that) is written in pigeon English.

Could you be specific as to how you removed the block? That is, did you use
something like an X-Acto (hobby) knife to cut around the perimeter, or just
pry with a screw driver? (or whatever). thanks.

Found this in an old file. I have not tried it myself.

@@@@@@@@@@@@@@@@@@@@@@@@


The dallas chips consist of 'regular' chip, with extra pins between
(in case of 24-pin devices) pin 1 and pin 24, and pin 12 and 13,
at the middle of the chip.

The top pins connect to a crystal, the bottom ones connect to one or
two lithium cells. These components are moulded in plastic compound
on top of the regular IC enclosure.

If the battary goes and you can't/won't find replacements, then you can
carefully try to pry away the moulding plastic in the hole
between pen 12 and 13. You will find two solder tabs with wires
soldered to it.

Remove the wires, connect two regular AA cells (minus to the pin
near pin 12, plus to the pin near pin 13), and you should be good
for many years to come.

 

[kony]

The dallas chips consist of 'regular' chip, with extra pins between
(in case of 24-pin devices) pin 1 and pin 24, and pin 12 and 13,
at the middle of the chip.

The top pins connect to a crystal, the bottom ones connect to one or
two lithium cells. These components are moulded in plastic compound
on top of the regular IC enclosure.

If the battary goes and you can't/won't find replacements, then you can
carefully try to pry away the moulding plastic in the hole
between pen 12 and 13. You will find two solder tabs with wires
soldered to it.

Remove the wires, connect two regular AA cells (minus to the pin
near pin 12, plus to the pin near pin 13), and you should be good
for many years to come.

That's a handy tip, but why AA cells? Usually the shelf
life of the cells is a greater factor than current and since
he'll need a battery holder either way it might be possible
to just use one smaller, small enough that it fits in the
available space without unduely long dongled connector.
For example if he wanted to use a std CR2032,
http://www.allelectronics.com/cgi-bin/category.cgi?category=search&item=BH-60&type=store
though it's essentially same thing one could pull off any
old motherboard.