Quadra 950 Ram Identification

[Sir Foxx]

Hello--

When I purchased my Q950, there were only 3 of these sticks plugged in, along with a couple of smaller 1mb modules.

I have been having a hard time figuring out what size these sticks are since I only have 3 of them, and have had no luck finding any on the internet, anywhere. I looked up the number on the chip, and I found a list of chip numbers and what size they are, and it said each chip is 4mb. If it is, and there is 32 chips on it, then that would mean it is a 128mb stick of ram..? Please help me find what size these are, and if anyone has any of these, please tell me because I am wanting a fourth stick to add to my machine.

Then again, on this list here (http://www.telegraphics.com.au/~fthain/dram/index.html#GM71C4100AJ70) it says 9 of these chips is 4mb, so if anyone has any advice here, please let me know!

The number is as follows -- GoldStar GM71C4100AJ70

 

[Trash80toHP_Mini]

I'm tired, but it sounds like you have 32 4MBx1 chips, 32 of which would add up to a 4MBx32 bit wide stick, AKA 4MB SIMM, IIRC.

 

[Sir Foxx]

So if I had 4 of these plugged in, it would total up to 16mb of ram?

 

[trag]

The HY514100 is a 4M X 1 DRAM chip. So it provides one bit of storage at 2^22 addresses.

Eight of them ganged together provides 4M X 8 storage, or a single 4 MB, 8 bit wide memory SIMM.

There appear to be four (is double-sided, yes?) groups of eight chips on that SIMM. So each SIMM is providing: 4M X 1 (single memory chip) X 8 (eight chips wide) X 4 (four banks of eight) = 16M X 8 DRAM memory.

Or, a single 16MB 8 bit wide, 30 pin SIMM.

Unfortunately, you do need four of them in order for the Q950 to use it.

That is a classic example of a "composite" SIMM. A memory module taken way beyond the day's capacity by essentially putting several SIMM's worth of memory on one board and adding a little logic to decode the addressing and direct things properly. They are power hogs and tend to produce excess heat.

It would probably be less time and trouble just to find a nice set of four 16MB 30 pin SIMMs which are built out of 16M X 1 parts (eight chips) or 16M X 4 parts (two chips).

They used to be about $30/set on Ebay until Howard Electronics went out of business.

 

[beachycove]

I have three matched 16MB 30-pin simms that look broadly similar and a fourth that make up the set, but which is of a different size and make. They work together without any problem.

I think a properly matched set is always preferable, but given that you have the three, you could do what I did and try finding any one 16MB 30-pin simm at the same speed (70ns) and see if that did the trick. If it did work, it'd be a good deal cheaper than four. If it didn't, well, you are not much farther behind than when you started....

 

[Sir Foxx]

Does the ram have to be the same speed? If it is 70ns like you say it is, could the fourth stick be 60ns, or would it not work with the other three sticks of 70ns ram?

 

[beachycove]

I think the crucial point is that the 950 requires 80ns RAM, and AFAIK, faster RAM (60, 70ns) will just run at that slower (80ns) speed.

Mine are the same speed, and all things considered, I would be inclined to match them as closely as possible, since you are asking the machine to do something slightly out of the ordinary. Still, a mistake won't break the bank.