Hopefully you can dump the other PAL's on the 5170.
Hi flyinghi5,
Thanks for your response.
Indeed, getting the PAL logic is complicated and was not only a simple matter of "dumping" something from the chip(we wish!), as you can read in my discussion with jonny64 earlier in this thread.
There have been various attempts I am sure but no one ever succeeded in this and published their results.
Even here on the forum there were earlier discussions which showed some equations but those were not complete and operational.
All the information you could possibly need in order to be able to repair a 5170 can also be extracted from my project schematics at GitHub.
There are two PALs and two PROMs on the 5170. For getting it to function you only need the PROMs and U87, U130 is only needed if you want to use a coprocessor. Otherwise it doesn't influence the normal functioning of a 5170.
You know what we also should do one day Johann?
To reverse engineer the PALs from the NCR PC-8 and the ARC X286 Model 12.
I am really curious how for they got in reverse engineering U87, because both these mainboards that I bought had a lot of issues.
This may be largely related to broken PCB traces or marginal TTL chips or even defective PALs however there also may be design deviations present, I would not be surprised.
I would first need to trace out the signal names so we can get correct equations.
That is, assuming that their "U87" is similar in function, they also could have made other circuit constructions of course.
As for me, from my experience testing these boards, the IBM 5170 stands out in solid stability compared to the other 3 mainboards I have.
I mean, the 5170 also suffered the wear and tear and influence of moisture etc due to mishandling and not keeping it in a friendly environment, but it kept going.
The board just feels very solid and strong which perfectly matches the "tank" case it came in. I am still looking for an original case!
Kind regards,
Rodney