Date: Sat, 26 Feb 2005 13:28:56 -0500 From: "classic" <[EMAIL PROTECTED]>
So your 6100 can see and use 264 megs RAM?
Yes, was surprised in a way but these chips came from a seller who claimed they work in an LC 475. He wasn't kidding.
http://www.kevinomura.com/6100/
I suspect this topic more properly belongs in 1st PowerMacs rather than Vintage Macs.
Thank you for this information. I bought four of these SIMMs on Ebay a while back but hadn't tested them yet and wasn't certain in which machines they might work. Apparently the Samsung SIMMs turn up on Ebay from time to time.
What is interesting is that the 7100 doesn't see the full capacity of these chips and I have an 8100 I can test but it's at the other end of the city so will take a while to get at it.
I've seen this reported somewhere else on the web but can't remember where. Oddly, the 6100 seems to support higher capacity individual SIMMs. But the 6100 definitely supports up to 264 MB of RAM if you use the correct SIMMs. I think that I read that the 7100 will support 64 MB SIMMs in two of the slots but not in the other two. But that's a vague memory.
The x100 family all use the same chip set and virtually the same ROM (the 6100 and 7100 do use the same ROM, the 8100 ROM is slightly different), so the underlying capabilities of the machines should be identical. Most likely, the SIMM sockets in the 6100 are wired just a bit differently than in the 7100.
It shouldn't be that tough to trace out the connections to the SIMM sockets in the various machines--just tedious.
Only other place that has big simms I have found is, http://www.micromac.com/products/bigsimms.html . But even they list the max amount of ram in these Macs at 136 mb. Maybe my 6100 can't count?
Ouch. $199 and $449 for 64 MB and 128 MB SIMMs. Ha, ha, ha, ha.... These folks have 64 MB SIMMs for $14 <http://store.yahoo.com/memorysuppliers/72pinsimms.html>, though I'm not certain that they are the correct single bank type. I bought a couple from them about three years ago, but have yet to test then. One interesting thing about the boards that they sent me is that they have blank positions on the back for another set of chips. This implies (assumign they're still using the same boards) that a person handy at soldering could buy two 64 MB SIMMs, move the chips from one SIMM to the other and end up with a 128 MB SIMM for $28.
A few years ago I tested memory in the Q605 which is the same as the LC and Performa 475/476. What I found is that 64 MB SIMMs need to be "Single Bank" in order to be properly recognized in the Q605. Double Bank is not recognized properly. I'm not sure exactly what Single Bank means, though I suspect that it has to do with using addressing to distinguish between address regions of the SIMM as opposed to using different Chip Enable lines to make the distinction.
I also tested the same SIMMs in the Power 120 which is basically a PM8100. In the Power 120, the SIMMs' recognized capacities were either halved or quartered, depending on whether it was a SIMM that was fully recognized in the Q605 or not.
Jeff Walther
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