TMS4164 RAM Tester
This Ebay bought RAM Tester I purchased as I was having a great deal of trouble finding four working RAM chips for my Electron Clone v2. I had about twenty 4164's but I could not find a working combination when plugging them into the Electron. Thinking I might not have a lot of working chips I also bought two lots of ten TMS4164's to see how they perform with this tester.
This RAM tester checks each memory location and either passes it with a Green LED of fails it with a Red LED indication. Not a lot of detail to see but it's enough to have a reasonable amount of confidence when plugging them into the Electron.
Starting the first batch of ten chips.
So the count is in - 60% pass for the first batch and 90% pass for the second. Of my original collection, nine failed out of twenty - no wonder it was hard to find a good combination.
This RAM tester can also test TMM41256 RAMs of which I had an original batch from the 1980's so I gave them all a quick test..
And they all passed.
I also found a tube of TMS4256 RAM chips which date back to 1987 and have the same pinout and capacity as the TMM41256 so I thought I'd try them.
And they also passed.
Conclusion - All in all a great but simple Go/No Go Dynamic RAM Tester. Every chip passed by the tester work OK in the Electron, what more could you ask for..