Dram tester

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Homer79
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Dram tester

Post by Homer79 »

I've seen a few dram tester projects around, I thought I would make my own.
I've not worked with dram before and I've been using a PIC16F628A to make a simple tester.
The bit which I've not found much information on is mapping the address to the RAS&CAS address.
If I use a TC514256A 256kx4 how would you map 0x10000 to the RAS&CAS address? I dont know if there a standard way of doing it?

My way of testing was to write 0000,1111,0101,1010 to each 4 bits, refresh and read them back and make sure they are the same. Then output on a serial connection if each address passed or not.

Regards
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rubber_jonnie
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Re: Dram tester

Post by rubber_jonnie »

See my post here: https://www.exxosforum.co.uk/forum/viewt ... =10#p34010

Someone has built a DRAM tester, and I've linked to it, it may be of use to you.
Collector of many retro things!
800XL and 65XE both with Ultimate1MB,VBXL/XE & PokeyMax, SIDE3, SDrive Max, 2x 1010 cassette, 2x 1050 one with Happy mod, 3x 2600 Jr, 7800 and Lynx II
Approx 20 STs, including a 520 STM, 520 STFMs, 3x Mega ST, MSTE & 2x 32 Mhz boosted STEs
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exxos
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Re: Dram tester

Post by exxos »

Currently I have a few different motherboards which I used to test RAM in... But at some point I want to design some RAM adapter boards for the H4 where I can test out various DRAM chips just by changing the adapter board... It would reduce the amount of motherboards I have dotted about for testing the chips.
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rubber_jonnie
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Re: Dram tester

Post by rubber_jonnie »

I have one board that's my test buck, with the first RAM chip socketed, but I also built a ZIF adapter that plugs in so I can use it for quick tests. Also considering putting a ZIF socket where all the chips are for quick testing of anything that isn't in a PLCC socket.
Collector of many retro things!
800XL and 65XE both with Ultimate1MB,VBXL/XE & PokeyMax, SIDE3, SDrive Max, 2x 1010 cassette, 2x 1050 one with Happy mod, 3x 2600 Jr, 7800 and Lynx II
Approx 20 STs, including a 520 STM, 520 STFMs, 3x Mega ST, MSTE & 2x 32 Mhz boosted STEs
Plus the rest, totalling around 50 machines including a QL, 3x BBC Model B, Electron, Spectrums, ZX81 etc...
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