Please help advise me on building a RAM tester

Hmm. Inputs: 7 address + 2 strobes + 1 enable + 1 data = 11 pins. Outputs: 1 pin.

There are 12 outputs and 4 (?) inputs from a standard parallel port. At 100Khz rep rate, that's 320ms or so to read/write the entire chip. Write 1, read, write 0, read, write 'random pattern' (to check 'stuck at'), read.

Maybe 2 seconds. Oh, connect 4 chip outputs to the PP inputs, and you're testing them way, way faster than you can plug them in. This will catch 99.99% of errors.

In a case like that, crosspost. Whoever answers should be smart enough to set followups.

...

Just one thought - why are you making a tester for chips that haven't even been made in about ten years?

Just build a general purpose Z80 SBC and use them for a bank of RAM. If they work, they work. If not, trash them.

You use the Z80 because it has a refresh cycle built into every fetch cycle. :-)

But why in the world try to resurrect such obsolete chips? Even if they _do_ work, they're a pain in the ass to try to use, and 4K of storage is practically nothing!

Good Luck! Rich

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Hi, Rich. Actually 2KB, which is even more worthless.

If all the OP wants is a basic go-nogo test, and isn't concerned about sorting for timing, most all of the old TTL IC testers had DRAM checks built in. Googling

"IC Tester" +DRAM

produces any number of TTL/CMOS/DRAM/RAM testers. The first one goes for the princely sum of $252 USD. It will give a go-nogo on these fossils. The gently used IC testers are even better priced. I know of one which works, as far as I know, and could be picked up for a six of Corona, a lime or two, and a few old UFW songs -- but I'd have to ask the guy, and haven't talked with him in a few years. I believe he got out of engineering about the time of the big collapse in 2001, and retired out west.

By the way, if you or anyone knows of anyone who wants to start up production of something with 4116s, I know a poor soul who got stuck with a few pallets of 'em when the music stopped (new, 1991 date code), as well as 4164s, and might be talked into getting rid of them at a reasonable price. Feel free to email me if you happen to be trapped in that Series Of Unfortunate Events, and I'll put you in touch with him.

10K minimum quantities, 100K+ preferred, fast delivery. Serious inquiries only.

Hey, Rich! Viva La Causa! Chris

Hey Rich, those are 16K x 1 IIRC. I bought a set of 8 for my Apple][ back in '80 for $50. At least 3 of them failed in the next few years. Whatever would some one want with those dinosaurs? Slower than mud. Dang, in November I bought a PC3200 512 Meg DIMM for $60. Its a might faster, too. GG

This smells like a homework type project to me.

It was even on my university's list of final year projects to choose from.

You can certainly do it with a printer port.

I hacked the top off a ceramic 4164 and experimented getting it to work like a crude camera!

A more interesting challenge would be to think of a project that found a use for these old DRAMs. I hoarded loads of 4164 and 41256 myself. 8K or 32K is quite big compared with many small micro's on-chip RAM.

Did he got stuck with these because of speculation on even higher memory prices?

If it was speculation he'd better aceept his loss.

Thomas

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With DRAM timing is critical for proper operation, any test that doesn't test this aspect is useless. The simple way is to find a piece of equipment that uses them and test by substitution, even that is a very poor test.

"Joe Magiera" a écrit dans le message de news:

3b7Rd.8823$ snipped-for-privacy@newssvr33.news.prodigy.com...

A very low cost and easy solution : Buy an old Apple II or Apple II+ (but not an Apple IIe !), which is equipped with 3x8 4116 RAM sockets for a great

48Ko total. Remove the top 16 of these 24 original RAM chips and put your RAM to be tested in these sockets, and run one of the "RAM test" software the used to be available for the Apple II... You will have an indication of the failing chip if any...

Friendly,

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Robert Lacoste
ALCIOM - The mixed signal experts
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Wasn't the 4116 used in some early video arcade games? If it was the people who collect and repair the old games might be interested in the chips. I remember a lot of static damaged memory from careless handling of the 4116 chips.

--
Beware of those who suffer from delusions of adequacy!

Michael A. Terrell
Central Florida

Hi,

No it isn't a homework project. One of the later replies did capture it perfectly though. Many classic video games from that era (1980-1984) used as many as 24 of the 4116's on a single boardset. I know they can be replaced with 4164's, but if really for nothing more than a "nothing else to do" project, and to test few thousand 000 of the 4116's I have lying around, I thought maybe I'd give it a try. Thanks for the replies so far though.

Joe

Just buy some new ones on ebay.... No bids so far... 50 for $1 perhaps