Testing 4532 DRAM

Using Arduino General Electronics
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Hi all, not sure this is in the right area but here goes.

I've seen plenty of projects for testing DRAM used in old 8 bit computers, mostly 4114 and 4164 found in the ZX Spectrum and Commodore 64.

The ZX Spectrum additionally uses the 4532 which is an odd chip. It's a 64k chip which has either a bad lower side or bad upper side, as indicated by L or H designation. For example 4532-20NL3 which indicates it's using the lower 32K.

Anyway, How to work with these DRAMs is way beyond my ability right now. I can do simple stuff like flash leds or turn a motor!

Is there anyone who is able to take one of these 4164 test scripts and convert it to work with the 4532 chips? Or at least maybe give me some pointers?

I did build this thing and it flagged some 4164 chips as bad, but the author said, in an email exchange, that he didn't really build it for testing chips.

Thanks,

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The chips are pin compatible. Simply try and report in case of problems.

BTW the Mega has a hardware interface for such chips which simplifies the code and speeds up the tests.

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I did try and it reported all the 4532 as good. Which is shouldn't do if half is supposedly bad. I notice the 4164 has A7 where as the 4532 as... something else, not got the sheet in front of me.

Good to know aboutv the MEGA.

thanks

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AR most probably tied to H or L - at least for RAS or CAS - A RAS?

Both H and L should be written into each cell, best differently in adjacent cells. Test after the entire memory has been written.

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Testing these devices is complex as you need to do it over temperature and at various speeds. All of the timing information etc is on the data sheet: UPD4164 pdf, UPD4164 Description, UPD4164 Datasheet, UPD4164 view ::: ALLDATASHEET :::
Yes I am familiar with the H/L jumper or other terms for that. When testing if a bad cell was found in 1 section and the other was ok it was flagged and shipped that way. If it met specifications it was shipped as the original part number. Many people figured out that they could use the bad section, many got away with it, many had product failures. Using the bad section will not damage it but it voids any warranties on the part.

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