info-mac@uw-beaver (info-mac) (07/19/84)
From: Dennis.Griesser@HIS-LA-CP6.ARPA Will it work? A previous transaction by Kevin <Mackey.PA@PARC-MAXC.ARPA> (dated 2/10/84) gave a summary of a talk by Dan Kottke, an Apple engineer. Among other things, he said: o It's very easy to put 256K chips in. o He expects several magazines to show everyone how to do it. o The PC board has 4 layers. No mention was made of other changes required to expand memory. I do remember a quote from somewhere (a magazine quoting Jobs?) that said NO other changes are required. If you go to the trouble of removing the RAMs, you might as well install sockets for them. Get good quality ones, don't skimp. How do you pull the old RAMs? Use the method that YOU have the most confidence in. I have tried squeeze bulbs, spring-loaded pumps, solder-wick, and fancy desoldering stations. I've tried to save the old chips, and I've tried sacrificing them. The thing that worked best for me, with least damage to the PC board was solder wick. No kidding! When considering whether or not to sacrifice old chips, consider the possible gains and losses. For the MAC, that means: Approximate cost of Mac................$2500 Approximate cost of new chips..........$1700 Approximate if-new cost of old chips....$100 The the old chips are only about 2% of your total investment. You could not sell them for anything near the if-new cost, but might find some project to put them in. I don't think it is worth risking the main MAC board to save such a small amount. New question: an equivalent amount of memory using 64K chips would cost around $300. How hard would it be to add three banks of cheap chips and save $1400 on the expansion?
info-mac@uw-beaver (info-mac) (07/19/84)
From: David Chase <rbbb@rice.ARPA> I can't stand it any longer. I think people planning to do their own 512k upgrades are crazy. 1) Who will fix a Mac that has been user-munged? (What crazed fool would offer to maintain a Mac when the user doodles with the innards?) 2) What will you do when the repairman wants to do a board swap? Tear out all the 256K chips so you can reinstall them in the replacement board? 3) I recommend against installing sockets because of bad thermal properties; chips will tend to die faster (and the Mac is already very hot inside). I have had some experience with this, using socketed Mostek memory and soldered DEC memory in a VAX 11/780. The Mostek boards (2.5 Meg of 16K chips) would lose about 10 chips per year; the DEC boards (1.5 Meg) lost maybe 1 chip every two years (wert.pa@xerox.arpa may correct me on this). The 780 ran MUCH cooler than the Mac, so I don't expect chip life in the Macintosh to be any better (though there aren't as many chips to break). 4) Adding more chips inside the Mac is also a loser, because you may cook the insides with the additional heat load. 5) If you must attack your Mac after all this, consider CMOS memory instead. It uses practically no power and runs very cool. While you are changing things, go whole hog and add a battery backup to your memory so that (maybe) the Mac need never be rebooted (you'll need to suppress the reset that probably comes from a power-up). It does cost a little bit more, but so it goes. (Note - I have a friend who worked on the HP Nomad, so I am right now a big fan of CMOS). drc