On Thursday, April 8, 2004, at 10:02 AM, Michael wrote:
on 04/06/2004 12:02 PM, John Niven at [EMAIL PROTECTED] wrote:Theoretically, they don't HAVE to be the same speed (some could be faster), but its nice if they are.
My IIsi will not work all day without having a freeze or bomb or
something strang unless the RAM is the same speed on all sticks. But that
may be due to the ROM stick that is in it.
Well I did say theoretically....... Most probably, the reason is poor MB design. Then (electrical) noise can be a problem. Could also just be that the decoupling caps have degraded over the years.
Non-parity 30 pin SIMMS come with either eight "by 1" DRAM, or two "by 4" DRAM. There is no technical reason why one should be preferred over the other, in fact the two "by 4"'s would be newer technology.
Some older software/programs and a few screen savers will freeze up with
the new high-tech 2 chip sticks. I have tried them all, the old 8 chip
sticks work the best, on this old horse.
Well you do have to be careful with refresh. The newer technologies have a smaller cell capacitor which would be less tolerant of out of spec refresh times. If you take your Mac somewhere cooler they may work better :-)
However, I usually remove the offending DRAM (by wire snips and de-soldering) as it saves a little power.
Now this is my kind of 'Learn Something New Every Day'. Is there more
about this somewhere. :-] I've got a 'few pounds' of nine chip sticks.
I don't know. Maybe I invented it :-) You may have noticed that often your 8 chip simms have an empty space. That's so the same PCB can be used for both parity or non-parity. If you have a 9 chip simm then you should remove the right hand chip when holding the simm with chips towards you and the connectors looking at you shoes :-)
When you have a three DRAM parity simm, one of the DRAMs will be different to the other two. Remove it.
I do this by using the wire snips to cut the legs of the right side, where you can get access. Then lift up the DRAM and rock it up and down until the legs on the otherside snap. You are done. Unless you are like me because then I use a soldering iron and copper de-solder braid to remove the last of the legs and clean up the solder on the pads. Radio Shack has the tools.
Of course, it's my understanding that this is NOT really necessary as parity simms should still work.
Now if you have any 4MB simms in that bag - I'll be only to happy to take them off you ;-)
Or send me the bag. I'll sort them, circumcise them ;-), and test them. Split them with you :-) I've got six SE/30, three IIci, and a Quadra 950 to feed.......
John
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