Parity SIMM with non-functional parity chip

[mikeyp]

I have been lucky enough to be able to purchase the IBM Enhanced Memory Expansion Adapter for my IBM 5170. I also ordered what should have been 8 3 chip 1Mx9 30 pin SIMMS.

They don't work in the 5170...

The 1Mx8 non-parity portion tests and passes fine in the retro chip tester pro. The parity test fails. The discussion on this point is here:

https://www.reddit.com/r/RetroChipTester/comments/16cjnz4

It seems the parity chip has been wired in any old how and the modules used in a non-parity form all their life. I have traced the PCB and the pinout is as follows:

CHIP > SIMM > FUNC
1 > 3 > DQ0
2 > 6 > DQ1
3 > 21 > _WE
4 > 27 > _RAS
5 > 9/22 > GND
9 > 16 > DQ4
10 > 20 > DQ5
11 > 23 > DQ6
12 > 25 > DQ7
13 > 1/30 > VCC
14 > NC
15 > 29 > PD
16 > 28 > _PCAS
17 > NC
18 > NC
22 > NC
23 > NC
24 > 10 > DQ2
25 > 13 > DQ3
26 > 9/22 > GND

My question is this: I can't find any data sheet or pinout at all for the BP41C1000A-6 1Mx1 chip but this makes no sense as these are all mixed up compared with other info I can find online on how to wire SIMMs. Is it safe to assume that all these 1Mx1 SOP24 chips have the same pinout? Could I remove and re-wire it per the pinout here? https://shop.griederbauteile.ch/info/k/KM41C1000BP.pdf

If it works, eventually I could do something similar to this: https://github.com/UpLateGeek/Let-s-Make-Some-Memories/blob/master/Schematic v1.pdf

 

[Radix]

It looks like you have fake or emulated parity and it's not fooling anyone...

https://www.memorytesters.com/sim1/simcheck_manual.pdf

 

[mikeyp]

Hmm. Ok. Nice to see someone has some reasonably current info on that chip. Digging way back I found this that suggested it was actually a memory chip. https://web.archive.org/web/20130307214429/http://www.telegraphics.com.au/~fthain/dram/index.html but if the above is right then no amount of rewiring address lines will fix the issue.

 

[Radix]

Yeah I think that's a list of everything that's been seen on a memory module - I vaguely remembered the fake parity chips when I saw your post - it was when RAM was really expensive and as usual, someone decided to cash in with fake cheaper RAM.. A lot of systems do not check the parity is actually working, i.e. by writing BAD parity data, so they never notice the magic parity bit that is always correct...

They might even be rare or a novelty now - but back to eBay for you!

 

[mikeyp]

Cheers for that. Better list them correctly!

 

[blossomkosher]

Cheers for that. Better list them correctly! snake io

In fact, many countries calculate quite difficult. But I like this topic.