Bringing a Pentium MMX SBC (industrial PC) back to life

i am planning (hoping more) to be able to get an industrial computer back to life

They are a weird kind of machine based on a backplane setup

I have a PC-BUS Backplane with 2 ISA Slot MMX CPU Cards.

Problem with one of the boards is that it has a DALLAS RTC that would need to be replaced and I need to find a Socket 7 CPU
This board is a ROCKY-518HV Socket 7 CPU BOARD (

The other board I have not checked nor powered on and is a PCA-6153 Pentium MMX CPU Card (

First step is to go thru the backplane and check all is ok
then the CPU cards



Good luck!

I moved this to the RetroChallenge 2021/10 Category. Be sure to keep us updated in replies to this topic on how it’s going.

Do you know what this was used for?

i am hoping once i get the it working the hard drive will reveal it
fingers crossed


Any advice on whether you I should replace the RTC with the same Dallas chip or the DS12887 RTC Drop-In Replacement?

Howdy, nice project!

I’ve come across those Dallas RTCs in the past disguised as a TH6887A.

I vaguely remember replacing it with a Dallas DS1287 / DS1287A / DS12887 as they were all compatible with each other. Unfortunately I don’t seem to have made any notes on what the outcome was! I believe they can be dremelled to reveal the coin cell inside if you are handy with a Dremel. I’m certainly not - don’t ask how I know… :smile:

Anyway, looking forward to learn what secrets the hard drive reveals about what this machine used to do!


I dremmeled one out of my dads old 486 in 2015. They don’t boot if they’re dead!!

1 Like

Ok who is up for a challenge ?

The challenge should you choose to accept Jim is…

  1. Desolder the Dallas Chip.
  2. Add a socket
  3. Put a replacement in

However if you or the chip you solder in don’t work we will disavow all knowledge
(Cue the mission impossible theme)

Nah honestly my soldering skills are terrible so I’ll strip what I can from this card and use it in the other one


How did your challenge pan out?