tom@fangorn.gsfc.nasa.gov (Thomas D. Schardt) (04/12/90)
We have four Mac IIs and a Mac IIcx and are going to load them up with memory. Are there any limitations on the speed of the SIMMs we buy? I assume we can't mix and match 80ns, 100ns, and 120ns chips. Also, can we take 1MB SIMMs out of the IIs and put them in a Mac Plus? Are there any speed limitations (or other limitations) to doing this? Thanks, Tom Schardt Bitnet: K4TDS at SCFVM NASA/Goddard Space Flight Center Internet: K4TDS@SCFVM.GSFC.NASA.GOV Code 632 Opinions expressed are my own and do not Greenbelt, MD 20771 necessarily reflect the opinions of my employer
jdevoto@Apple.COM (Jeanne A. E. DeVoto) (04/13/90)
In article <1626@dftsrv.gsfc.nasa.gov> tom@fangorn.gsfc.nasa.gov (Thomas D. Schardt) writes: >We have four Mac IIs and a Mac IIcx and are going to load them up >with memory. Are there any limitations on the speed of the SIMMs >we buy? I assume we can't mix and match 80ns, 100ns, and 120ns >chips. Also, can we take 1MB SIMMs out of the IIs and put them in >a Mac Plus? Are there any speed limitations (or other limitations) >to doing this? For both these machines, you need SIMMs that are 120 ns or faster. Both have 2 banks of 4 SIMM sockets each. You can mix speeds as you like, since memory access on the Mac is synchronous; however, all SIMMs in a given bank must be the same density, and each bank must be either completely full or completely empty. This means the possible configurations using 1M or 256K SIMMs are: BANK A BANK B TOTAL 4 256K none 1M 4 256K 4 256K 2M 4 1M none 4M 4 1M 4 256K 5M 4 1M 4 1M 8M The Plus (and SE) require SIMMs of the same type, 150 ns or faster, so any SIMMs fast enough to work in a II will work fine in a Plus. The Plus and SE have 2 banks of 2 SIMM sockets each and follow the same rules as above, so the possible configurations for these machines are 512K, 1M, 2M, 2.5M, or 4M. -- ====== jeanne a. e. devoto ======================================== jdevoto@apple.com | You may not distribute this article under a jdevoto@well.UUCP | compilation copyright without my permission. ___________________________________________________________________ Apple Computer and I are not authorized | CI$: 72411,165 to speak for each other. | AppleLink: SQA.TEST