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Old 23 May 2015, 22:13   #1
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Reading Amiga DRAM


Im working on a bit of hardware to test some of the DRAM I have from my Amigas - Im planning on doing this with an arduino and a bit of soldering.

However, I've hit a wall; Im sitting here with some DRAM, and it appears to me that they are a bit more tricky to access than any other RAM Ive worked with before - especially this refreshing the DRAM cells-business.

Anyone has any experience with DRAM testing ?
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Old 24 May 2015, 12:25   #2
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You're looking at creating a simplistic DRAM controller. This is still possible to bit bang with the Arduino, perhaps use the CAS before RAS refresh method to keep it simple.

This should enlighten you. https://www.ece.cmu.edu/~ece548/localcpy/dramop.pdf
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Old 24 May 2015, 15:03   #3
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working with dram is quite simple - read datasheet for IC you intend to use, most of 256kbit (256kx1) chips and AFAIK all 1 mbit (256kx4) are equipped with internal refresh counter so they not require any external logic to refresh (CAS before RAS).
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Old 25 May 2015, 03:21   #4
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What might have confused me was a older project for the arduino, where interrupts for refresh was enabled and installed.

I have managed to make a... not so pretty.. .. but working.. DRAM tester

Edit: actually was really confused me was the timing-schematics of my 20pin dram in the data sheet. They are, from a no-technician (but yet, 20 years of coding) pretty darn weird to look at ! :-)

Last edited by _tweak; 25 May 2015 at 03:29.
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Old 25 May 2015, 19:28   #5
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and i forgot to attach the image of it; its not pretty but it works ! :-)
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