kraut@ut-emx.UUCP (Werner Uhrig) (03/26/88)
some weeks ago I posted 2 queries, one regarding the needed jumper configuration for using 2.5Meg in a Mac+, consisting ONLY of 256k chips (rather than 2 SIMMs of 1Meg chips and 2 of 256ers). I received NO pointers to sources of SIMM carriers and I received only one msg with a recommendation on how resistors/jumpers need to be configured for 2.5Meg (mainly what is stated in Apple's Tech Note which I knew already) but without having tested it. RESULTS: 1) the only source for carriers for 256K SIMMs are still the ones that MacMemory sells with their MaxPlus 2Meg upgrade - and they won't tell where one can get only the carrier. 2) to run with 2.5Meg, you need to remove the resistor labeled 256-ONLY but not install the jumper for 1-ROW-ONLY. 3) to run with 2Meg, you do NOT have to remove the 256-ONLY resistor, as Apple's Tech Note would have you believe. Both MacMemory and Dove 2 Meg upgrade take advantage of that and they only require installa- tion of a jumper which is identical in function of installing a resistor in the space marked 1-ROW-ONLY. one company recommends installing that jumper between pins 11 and 12 of a chip labelled CAS in position E3 on theeeemotherboard, the other recommends jumping pin 11 of CAS with the capacitor C18 just above the chip BMU2 in position E2, on the side of the capacitor oriented towards E3. I had received no requests for results of my query from anyone, but, just maybe, this may help someone else. BTW, I've "mixed-and-matched" my 2 Meg configuration using 256K-SIMMs and/or 1Meg-SIMMs ... and never did cut the 256K-ONLY resistor ... -- (prefered mailbox:) werner%rascal@sally.utexas.edu ....!ut-sally!rascal.ics.utexas.edu!werner (if rascal is unreachable:) werner@astro@sally.utexas.edu werner@utastro.uucp