VOGONS

Search

Common searches

Replace DS12C887 Dallas chip

Topic actions

First post, by tabm0de

Posted on 
User metadata
Rank Member
Rank
Member

I know i can still buy the chip but would be nice to replace it with something like Necroware's NW12887 RTC module or equal, but what i do understand it is not the same as DS12887 as DS12C887 "it uses the century byte differently to a PS/2"?

The DS12887 is not Year 2000 compliant, but of course PS/2s are compliant except that a manual reset of the date is required at the start of the year 2000. Do not be tempted to use the Year 2000 compliant upgrade to the DS12887, which is designated the DS12C887; it uses the century byte differently to a PS/2 and will apparently not work.

The board manual says "Dallas RTC battery or compatible" and has DS12C887 i feel its a bitt unclear 😀

if any one have any information feel free to share 😀

naa, nothing yet...

Reply 1 of 6, by dominusprog

Posted on 
User metadata
Rank Member
Rank
Member

Why not mod the Dallas chip you have?

Duke_2600.png
A-Trend ATC-1020 V1.1 ❇ Cyrix 6x86 150+ @ 120MHz ❇ 32MiB EDO RAM (8MiBx4) ❇ A-Trend S3 Trio64V2 2MiB
Aztech Pro16 II-3D PnP ❇ 8.4GiB Quantum Fireball ❇ Win95 OSR2 Plus!

Reply 2 of 6, by Jo22

Posted on 
User metadata
Rank l33t++
Rank
l33t++

+1

https://www.classic-computers.org.nz/blog/200 … attery-chip.htm

"Time, it seems, doesn't flow. For some it's fast, for some it's slow.
In what to one race is no time at all, another race can rise and fall..." - The Minstrel

//My video channel//

Reply 3 of 6, by jakethompson1

Posted on 
User metadata
Rank Oldbie
Rank
Oldbie

Sounds like a BIOS compatibility issue?

I've put DS12C887A+ in place of DS12887A on mid-90s Award BIOS boards and it's always worked. The "C" version is a few cents cheaper if I remember right

Reply 4 of 6, by Horun

Posted on 
User metadata
Rank l33t++
Rank
l33t++

Agree jakethompson ! The dallas with century byte uses a specific location (32h) that may have issues with the bios.
Another issue is the diff of 113bytes versus 114bytes cmos data that some bios have issue with....
If the manual has that warning about changing Dallas chips then I am with others and suggest you do the mod on a plain DS12887.
Necroware replacements come with some issues with certain motherboards so I cannot recommend them unless some one else has posted their success with same vintage system.
I have modded multi dallas and bought good replacement dallas with near 100% success, in your case I suggest doing the mod.
Hope your dallas rtc is socketed or else you face other challanges 😀

Hate posting a reply and then have to edit it because it made no sense 😁 First computer was an IBM 3270 workstation with CGA monitor. Stuff: https://archive.org/details/@horun

Reply 5 of 6, by andysarcade

Posted on 
User metadata
Rank Newbie
Rank
Newbie

Just thought i'd interject here, I have a 486-5x86 ISA SBC (Protech PC-420) that uses the 12C887 and it does *NOT* work with the necroware 12887 replacement (more precisely its a F*** Dallas replacement version). If you put something else in there, it just beeps high and very rapidly forever, its not happy about it. So some bios's probably know when you're not putting the right type in. Might work fine in some systems, or putting a 'C' into a non-C setup, but not this way round apparently.

XT, 286, 386, 486, P200mmx, P3, P4, all the voodoos.

Go to top of page Go to top of page
Back to General Old Hardware
Close window
Close window