Almost free RAM

32K x 8 bits = 256K bits SRAM

I have a lot of 32Kx8 SRAM and 256Kx1 DRAM.

Maybe someone can think of a good application for them.

Thanks for the information, Kryten.

John

I'd love those chips. RAM chips are hard to buy individually. You'd have to get them in bulk. SRAM chips especially more so since these days caches are built in to the CPU. And most modern cache and buffer rams on motherboards are DRAM since these days they are fast enough (up to 500MHz).

I design and build CPUs as a hobby and SRAM chips are so much simpler to use since I don't need to do refresh. I usually get them off very old motherboards (pre 1998).

Unfortunately, living in Malaysia means that the shipping will be very expensive for me.

Anybody have a 628128 static RAM they would like to send to a good home? I would like to update my Tandy WP-2.

I have 16 each NEC D43256-85L integrated circuits. I believe them to be 256 (bits/bytes?) SRAM devices. They are in the 28-pin wide-body DIP package. Obviously, they are old, probably 1993 (if I'm reading the date code properly).

I have no need for them. I would like to find them a loving home where they will be most useful. I will ship them to whoever is willing to pay the DHL shipping costs (shipping method is convenient for me so it is non-negotiable). The first respondent with the most dire need (if there is such a person/need), will get them. My zip code is 75074.

Unmunge my email address to reply privately. If I hear nothing, either publicly or privately by Monday afternoon, I will make the ICs a home in the trash.

Cheers, John

I have 16 each NEC D43256-85L integrated circuits. I believe them to be 256 (bits/bytes?) SRAM devices. They are in the 28-pin wide-body DIP package. Obviously, they are old, probably 1993 (if I'm reading the date code properly).

I have no need for them. I would like to find them a loving home where they will be most useful. I will ship them to whoever is willing to pay the DHL shipping costs (shipping method is convenient for me so it is non-negotiable). The first respondent with the most dire need (if there is such a person/need), will get them. My zip code is 75074.

Unmunge my email address to reply privately. If I hear nothing, either publicly or privately by Monday afternoon, I will make the ICs a home in the trash.

Cheers, John

I have 16 each NEC D43256-85L integrated circuits. I believe them to be 256 (bits/bytes?) SRAM devices. They are in the 28-pin wide-body DIP package. Obviously, they are old, probably 1993 (if I'm reading the date code properly).

I have no need for them. I would like to find them a loving home where they will be most useful. I will ship them to whoever is willing to pay the DHL shipping costs (shipping method is convenient for me so it is non-negotiable). The first respondent with the most dire need (if there is such a person/need), will get them. My zip code is 75074.

Unmunge my email address to reply privately. If I hear nothing, either publicly or privately by Monday afternoon, I will make the ICs a home in the trash.

Cheers, John

I have 16 each NEC D43256-85L integrated circuits. I believe them to be 256 (bits/bytes?) SRAM devices. They are in the 28-pin wide-body DIP package. Obviously, they are old, probably 1993 (if I'm reading the date code properly).

I have no need for them. I would like to find them a loving home where they will be most useful. I will ship them to whoever is willing to pay the DHL shipping costs (shipping method is convenient for me so it is non-negotiable). The first respondent with the most dire need (if there is such a person/need), will get them. My zip code is 75074.

Unmunge my email address to reply privately. If I hear nothing, either publicly or privately by Monday afternoon, I will make the ICs a home in the trash.

Cheers, John

Yes, I noted the way things were going and made efforts to grab DIP RAM while it was discarded in old PCs. I've got enough for the dozens of projects I have not thought up and don't have time to do... :-)

The CPUs themselves or boards using microprocessor chips? Which ones do you use, and do you have web pages?

Design a good project on the web and maybe interested readers will donate chips you request. But only after the design is up, no point people moving stuff from their parts box to yours if they are not going to get used.

Don't write off DRAM chips. They are not that hard to use. They use half the address lines, so you could add 8 or 32 K storage to a small microcontroller project.

Have you checked the socket and the machine will accept this chip?

has a full 13MBytes service manual with circuit diagram.

I can't see a DIP socket for RAM on the board:

There is one DIP socket but it holds the ROM.

Or does it sit in the IC card slot?

Yes. I have some Hitachi HM628128LFP-7 128K x 8 SRAMs in the so-32 package (0.5" wide, 0.05" lead pitch), carefully removed from working boards by yours truly. If suitable, I'd be happy to send a couple to one of my lovely northern neighbors.

James Arthur (e-mail address is good)

Audio delay generator. :-D

Cheers! Rich

Hey, nice site! It's always nice to see old computers well-loved & supported.

It seems he needs a DIP package rather than the so-32 I offered... the site you provided says:

"My units came ... with 64K of RAM installed (32K is soldered on the mainboard, 32K is provided by a socketed DIP-package 62256),"

and

"Note that for $5.90 you can buy a 628128 128Kx8 RAM chip to replace the 32K expansion chip;"

The link goes to the appropriate page at Futurlec, which still offers the part for $5.90, qty 1.

James

True.

Lewin does get up to some impressive tinkerings.

I balked at the 13MB file size, but I still think like a guy with dial-up and a 100 MB disk! :-)

I have the urge to turn it into HTML but I don't think the number of interested readers would justify the effort. And I have other documents that have prior demands on my time.

Nice. I here Digikey is the default source in the USA.

I'm alarmed that Maplin - a hobbyist supplier - only sells this size RAM in surface mount. Surely they should be aiming at the hobbyist with 0.1" holed prototyping board?

Strangely, the professional supplier RS Components do sell it in DIP32: uPD431000ACZ-70LL

According to DHL, the cost is $46.46 (USD) to ship them to Kuala Lumpur from the Dallas area of Texas (USA).

Cheers, John

I hear that the Indonesian postal service is pot luck.

If it is worth pinching they will nick it, and if it is not then they will just dump it. Nobody trusts them much.

I once hooked up lots of 74161 counters to cycle through the addresses, and built myself a 32*32 pixel graphics card using a 2102 1k*1 SRAM. Pointless but educational. I learnt that the adddress counters are more work to wire than the RAM itself. These days, I think probably the best way to count through the addresses is to hook up one of those shift-registers with feedback from an XOR gate hooked up to a couple of the bits of the shift register (it's in AOE as s pseudorandom bit sequence generator). The whole contents of the shift register would be used as the address word. The addresses wouldn't be accessed in the usual order but as long as you do it the same when reading and writing, it doesn't matter what order you use. The point is that you can build it with 74HC273 chips or something like that, rather than needing a proper synchronous counter. Also it would probably count a bit faster than a counter built from 74HC161s. It would only count through (2^N)-1 of the addresses, but in most applications one wouldn't be too upset to miss the very last address. As you can tell by the fact that I have bothered to think about this stuff, I am one of those people who doesn't use FPGAs yet.

Chris

hi, could you point to some good references on dram refresh and maybe some circuitry to do that? you sound knowledgable on dram, maybe you can point me to some spec/data sheets on dram. maybe you even have an old pdf datasheet for an old 4meg 30pin simm you can share? or anybody else? I just happen to have a few dozen laying here I would like to use for something/anything. thanks. this is a nice group here and also a lot of knowledge.

Ken

They are worth very little. Try putting them up on eBay.

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