Where do you go to find memory chips?

[Juror22]

I was wanting to get some Hitachi 658128ALFP-10 chips for a project, but I know next to nothing about the naming (I'm guessing that the 128 is the amount of memory in Kilobytes - is that correct and what does the rest mean?) Will similarly named chips will have similar characteristics. Low cost would be nice (I need about 16 to start with). The Google search returns a lot of what I would guess are chip procurers and no one lists prices. Has anyone dealt with trying to get these kind of items and have any suggestions/direction or hints?

 

[MinerAl]

Could you just buy two populated 8-chip SIMMs and unsolder the chips?

 

[trag]

From another thread, I think Juror22 is looking for Pseudo-Static RAM chips. Not regular FPM DRAM chips.

Juror, I have over 100 of the Hitachi HM658512ALFP on hand. These are 512K-word X 8-bit chips. I expect these are the same as the Hitachi 658128ALFP-10 but with four times the density.

Those websites you're finding are all irritating. They'll ask you to request a quote, and then ask you to pick a target price. And either your target price is too low and they never respond, or it's too high and you overpay, but the quantity you listed is too low to meet their minimum, so they won't sell it to you anyway.

That said, I'd try questcomp.com if you really need the '128' version. They seem to have some older, harder to get parts with actual prices listed on their website. Some parts come up as "call for quote", but many of them have actual prices listed.

I just watch Ebay for interesting memory chips, but that's how I ended up with an attic full of stuff like over a hundred of a memory chip I'll never use unless I build a memory upgrade for a computer I don' t have...

If you'd like me to email you the datasheet for the chips I have, PM me your email address.

Oh, never mind, I just remembered that I sold you caps a week ago. I've emailed you the datasheet.

To answer your base question, there is not a systematic naming convention for memory chips. Numbers preceeded by a dash, after the main part number usually indicate the speed rating of the parts. And some chip manufacturers used 256, 1000, and 4000 to indicate those sizes of parts in kilobits. But others used things like 1001, or 4004 and 4001, where sometimes (but only sometimes) the trailing 1 or 4 indicated the bit width of the device.

Really, one must get the datasheet for any part one is interested in and read it, to determine what a part really is.

And I just hunted down the HM658128 datasheet and emailed you that for comparison. Googling for datasheets tends to bring up all those irritating chip merchants who don't actually have any stock, nor datasheets, but all want you to fill in an RFQ. When searching for datasheets, datasheetarchive.com tends to be your best bet.

 

[Juror22]

Thanks for the responses.

Trag is correct as to the type of chips that I am looking for. I am reviewing the data sheets that you sent along.

Thanks again

 

[James1095]

What are you trying to do with them?

Keep in mind that the brand is likely irrelevant unless it's a really unique part that nobody else made. Most memory devices follow JDEC standards for pinout and function, so a RAM chip or EPROM from one manufacture is normally interchangeable with similar devices from other manufactures.

 

[trag]

I believe that he is trying to replicate the memory expansion card for the Mac Portable. He requested a photo of one in a different thread.

 

[Juror22]

You surmise correctly - I've been requesting various bits of information to check into my options for the 6 1MB cards that I recently got.

Option 1 - buy additional chips and upgrade the cards to 3MB... the cards are identical (resistors, chips, everything).

Option 2 - canibalize the existing card's chips - the yield is 2 3MB cards and 4 empties

Option 3 - if, as I suspect, there are minor differences between the 3 and 7 MB cards, get the different chips and make the additional modifications (if any)

hopefully, I will be able to put together 7MB cards - I really want to upgrade my Mac Portable

 

[Bunsen]

Another source of odd and old ICs I've recently discovered is utsource.net. octopart.com is the main one I've been using previously, but so far utsource seems to turn up more actually available parts.

trag, thanks for the ref to questcomp: I hadn't heard of them before.

 

[GregorHouse]

You surmise correctly - I've been requesting various bits of information to check into my options for the 6 1MB cards that I recently got.

Option 1 - buy additional chips and upgrade the cards to 3MB... the cards are identical (resistors, chips, everything).

Option 2 - canibalize the existing card's chips - the yield is 2 3MB cards and 4 empties

Option 3 - if, as I suspect, there are minor differences between the 3 and 7 MB cards, get the different chips and make the additional modifications (if any)

hopefully, I will be able to put together 7MB cards - I really want to upgrade my Mac Portable

Did you have any success in it? I've just got a backlit Portable, and I'm considering options.

 

[Juror22]

Actually, relatively shortly after this, Tech Knight was offering 'home-made' 8 MB cards (they worked with both backlit and non-backlit models)and I picked up two of them.  They are excellent, but hard to come by these days.

Prior to that, I had messaged someone on the board about posting pics of the 7MB card, but I'm unsure of whether or not they had responded with a picture.  I did get 24 of the chips to experiment with populating the cards from 1 MB to 3MB, but by the time I got an hot air soldering station, I had the other 8MB cards and these became yet another project sitting on the shelf.  I literally have the box with the 6 1MB boards (one was bad when I tested them, so actually 5 working boards) and the 24 chips, all in static packaging, waiting for the day that I get back to them.  Making the 3MB card out of a 1MB card is as simple as soldering on the missing chips (there are no capacitor/ resistor changes, as I recall)

 

[GregorHouse]

I read that thread about techknight’s home made card. What a job he did, who could get one of these this days… :’(

Thank you for your comment. I have ordered two cards, I’ll try to make a 3MB card.

By the way, any chance this can be further upgraded by soldering larger capacity ICs? The PB 170 use the same chips, only they are 512KB each, instead of 128.