Source for Repro Simm ram chips?
- Thread starter ZweiGP01
- Start date
kazuo
Champion
AFAIK you're basically rolling the dice with AliExpress resellers. Entirely possible they're fake too, so YMMV. Are these chips EOL?
hatmoose
Enlightened
I found testing and troubleshooting repro Simms to be exceptionally time consuming
The only way I can make sure they are working is to solder all 8 chips to SIMM then write a game to them (probably several games to be sure). Sometimes my bad SIMMS will fail with a useful warning (YX where X is the slot with the bad Simm) but other times the write just hangs and I have to guess based on progress, or test each repro Simm individually in a batch of other known-good Simms.
Then problem 2 is figuring out which of the 4/8 chips on the SIMM is bad. Its possible to test the N(ormal) pinout chips individually out of circuit with a modern EPROM programer, I use a T48 with ADP-F48-EX-1 adapter
But the R(everse) pinout chips I have not yet found a testing solution for, If you do know of one...
The only way I can make sure they are working is to solder all 8 chips to SIMM then write a game to them (probably several games to be sure). Sometimes my bad SIMMS will fail with a useful warning (YX where X is the slot with the bad Simm) but other times the write just hangs and I have to guess based on progress, or test each repro Simm individually in a batch of other known-good Simms.
Then problem 2 is figuring out which of the 4/8 chips on the SIMM is bad. Its possible to test the N(ormal) pinout chips individually out of circuit with a modern EPROM programer, I use a T48 with ADP-F48-EX-1 adapter
But the R(everse) pinout chips I have not yet found a testing solution for, If you do know of one...
Jesus, well shit. I thought it would be a bit easier nowadays. I just have to hope for a set of good ones. Lol.
kazuo
Champion
This guide might be helpful for testing SIMMs.
If you don't want to DIY, there's a seller on Ali offering repro SIMMs. Unfortunately I don't think DS has any available.
If you don't want to DIY, there's a seller on Ali offering repro SIMMs. Unfortunately I don't think DS has any available.
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hatmoose
Enlightened
Love this guide, thank you very much, would never have found it otherwise.
Also designed this, its a Normal to Reverse adapter for the t48. Found to the reason that no-one sells them which is that every chip maker has a different idea of what "reverse' means - Fuj is flipped x, AMD is flipped y, others pretty much reassign the pins at random.
So this one will ONLY work with the MBM29F016-PFR (if it works at all) If it does work I'll polish up the cads and share them
Edit: oops, forgot to post the link to the adapter, yes. tested and working fine, details and CADs here
https://www.arcade-projects.com/thr...-1-to-read-write-mbm29f016-90pfr-chips.30477/
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