pottle@batcomputer.tn.cornell.edu (Chris Pottle) (02/27/90)
I recently purchased 4MB of SIMM memory. I installed 2MB in each of two practically identical Mac Pluses, both upgrades from 512Ks. Each Plus has a DataFrame hard disk (one with a much older driver than the other). One of the machines seems to work perfectly. The other crashes in several spectacular ways when applications are launched under Multifinder (Excel is an exception). I swapped the hard disks, expecting the problem to move with the disks. It didn't - the problem is with the machine. I understand applications load in different areas of memory under Multifinder than under Finder. Question: How thorough is the memory test done at startup (both machines pass this test)? Can anyone provide me with a memory diagnostic application which will tell me if one of my SIMMs is bad? Chris Pottle (pottle@tcgould.tn.cornell.edu)
marc@Apple.COM (Mark Dawson) (02/28/90)
In article <9805@batcomputer.tn.cornell.edu> pottle@tcgould.tn.cornell.edu (Chris Pottle) writes: >I recently purchased 4MB of SIMM memory. I installed 2MB in each of two >practically identical Mac Pluses, both upgrades from 512Ks. Each Plus has >a DataFrame hard disk (one with a much older driver than the other). One of >the machines seems to work perfectly. The other crashes in several >spectacular ways when applications are launched under Multifinder (Excel is >an exception). I swapped the hard disks, expecting the problem to move >with the disks. It didn't - the problem is with the machine. I understand >applications load in different areas of memory under Multifinder than under >Finder. >Question: How thorough is the memory test done at startup (both >machines pass this test)? So-So. The main problem is speed (of booting). The diagnostics we ship to dealers take 40 seconds to a couple of minutes to test 8 megs of memory (depending on how many passes are run). One 3rd-party program (I forgot the name--sorry) took 8 hours to do a real thorough test (it did about 100 different types of memory tests). Our marketing people decided that 40+ seconds were too long to wait EACH time you booted up (before you even got the system software to start booting). Even on a Mac+ system with 1mb, you may wait an extra 5 seconds or so (which was deemed too much). Generally, engineering has been slowly winning the testing battle with market- ing, with the result that the new machines (like the IIci) have better RAM testing than older ones. So your problem COULD be flaky RAM (make sure you've seated it correctly/snugly since that is a major cause of problem RAM). Hope this enlightens you somewhat. Mark
saf@floyd.ATT.COM (Steve Falco,14D-327,4865,ATTBL) (02/28/90)
> So your problem COULD be flaky RAM (make sure you've seated it correctly/snugly > since that is a major cause of problem RAM). I just added 2 megs to a mac+ bringing it up to 4 megs (yeaaaa!) The first time I installed the RAM I got vertical lines all over the screen. Wiggled them a little and everything seemed to be fine. Sadly, it became a crash-o-matic with MPW staying up for maybe 20 minutes at a time. The errors were totally random. I removed all the RAM and painted the connections with Cramolin (a contact cleaner sold for high-end stereos among others). I also pulled off every cable I could find and painted them too (since I had "dancing-screen" syndrome a while back). One observation I have is that the new SIMMs seem slightly thinner than the old ones. I don't know what the spec is nor did I put a micrometer on the new ones but I sure would be annoyed if 2 cents worth of fiber-glass is the root cause of the problem. Anyway, it ran for 3 hours doing compiles last night with no problems. Is it fixed? I hope so... Steve Falco saf@floyd.att.com