Old DRAM sources

[joeh]

I need to find a source for some old 1Meg*1 (DIP package) DRAM (i.e., 411000 or 511000). Of course, used parts are OK.

Any help is appreciated.

Joe

[Fruss Tray Ted]

Hey Joe,
Welcome to http://www.pcguide.com/ubb/pcgubb.gif

Is that for a laptop? Let us in on what you have and we can look (http://www.computersurplusoutlet.com/showproduct.asp?category=6&subcategory=21) around for a site (http://www.crosscomponents.com/?trackcode=bizcom) or two.

Us knowing what you are working on may open possibilities of some sort of upgrade in amount of RAM at least.

1 meg huh? Boy that's a tall, or should I say short, order :rolleyes:

[joeh]

The application is an original design of mine that uses a CVDS chip to record Audio (0-3Khz). The Design supports up to 64 1Mb (DIP) devices but they are individually addressed. One thought I've had is to strip off some old 8MB SIMMs and use the surface mount parts, but that would require either a re-layout of the PCB or the layout of a daughter-card adapter. Both are possible, but not preferred. Unfortunatley, because of the way in which the CVSD chip accesses the DRAM, the SIMMs are not useable without some kind of modification (each DRAM is selected individually...i.e., the CVSD device is bit oriented, not byte).

Higher density parts would be difficult because the CVSD chip handles refresh and is limited to the 1Mb address limit. Simply tacking on more address lines would require additional effort to perform refresh.

Other memory technologies also record audio (ISD) but I don't have enough demand to warrant that degree of redesign.

FYI, the CVSD chip is a TI TMS3478 (long obsolete, but I have plenty). A schematic is available at:

http://www.rollanet.org/~joeh/FFtp/DVR manual.pdf

The design is kinda ugly, but it works. I know the design is near (OK, well past) end of life, I'm just trying to milk it a little while longer.

Of minor interest is that they never made DRAM slow enough that it wouldn't work, and the system is even tolerent of random bit failures.

I hope that isn't too much info...

[joeh]

OK, this URL may work:

http://www.rollanet.org/~joeh/FFtp/DVR%20manual.pdf

[Fruss Tray Ted]

I like reading your posts but I must confess I'm not your source for info. As interesting as it sounds, I'm waay behind on where I should be. I took HS Electronics in the 70's when tubes were still common and transistors also. Got out of school and didn't do anything with it till I got my first pc, Win95 and a 66mhz processor. I've got a lot of catching up to do, that is if I ever find enough time...

I've looked at my old text book and notes from time to time and said to myself how things are soo~ different now.

Good luck in your search. Oh, and along the way,, if you happen upon a can type MOSFET: K176 or QP113 or ON113, shoot me a link would you , please? :) I got a Hafler 500 'souped up' by Digital Concepts (edit: not sure on the name of the biz, the amp is not here) I've been tryin to fix for some time now, put it on a shelf for awhile but just blew the dust off and renewed my search. I would just love to get that puppy running again!

Accidentally shorted one output channel and lost only one component, but I'll be doggoned if I can find one like it!

[saphalline]

Did some google searching trying to find pics of what DIP DRAM chips look like. Wanted to make sure I know what you mean - are those the kind used for L2 cache modules on old 3/4/5-class x86 mobo's?

[mjc]

Yep.......thems the ones.

[joeh]

I don't know about L2 cache, but those processors (mostly x386 and prior) are ov the vintage that might have seen these parts on their mobos.

As for my search, my problem looks to be myopia. I was searching for DRAM when I should have been searching for "surplus electronic components". Short story long, I've found a suplier who appears to have what I want.

Thanks for the help.

[saphalline]

I don't know about L2 cacheWell, I meant the packaging type. The "DIP" thing confused me, but you're right. L2 cache modules of the DIP package were usually SRAM, not DRAM.

Congrats on your findings. Not easy to find "old" parts is it? As much as I love technology going forward, it's a bit frustrating at times. I mean, there are just certain applications that will never need the obscenely powerful parts that we have right now, yet they keep moving forward. :rolleyes: