At 08:37 -0500 11/28/2002, Cole wrote: >According to the book, it can only handle 64Mb sticks (total >of 144). Since the 128Mb sticks are only a few bucks more >at OWC, I would prefer to put in a couple of these. The >guys at work think that the 64Mb limitation was because that >was all that was available at the time it was made.
That is true for some models, but not for this one. 64 MB is the limit. If you install 128 MB DIMMs, they will be treated as 64 MB. In theory this should be reliable, but I don't recall anyone reporting whether it works well or not, so you might be pioneering if you try it. The reason it's limited to 64 MB has to do with the address lines which Apple implemented to the memory slots and the RAM address modes which are supported. RAM is kind of odd in that instead of addressing it all at once (32 bit addressing--send 32 bits at a time), it is addressed in Rows and Columns. So, first (or maybe second) the computer tells the RAM, "this is a ROW address" and it sends a 10 - 13 bit address. Then (or maybe first) the computer tells the RAM "this is a column address" and sends another 10 -13 bit address on the same address pins used for the Row address. Then the RAM puts it all together and delivers the goods. This weird method does save on the number of address pins required. Furthermore, only certain modes of Row/Column addressing are supported. Examples of modes would be 13 Row address and 9 Column address. Or 13/11, etc. The C series only supports enough address pins to memory and only supports addressing modes which will let it recognize up to a 64 MB DIMM. I think Apple's "PPC_5500_6500.pdf" lists the supported addressing modes Jeff Walther -- SuperMacs is sponsored by <http://lowendmac.com/> and... Small Dog Electronics http://www.smalldog.com | Refurbished Drives | Service & Replacement Parts [EMAIL PROTECTED] | & CDRWs on Sale! | Support Low End Mac <http://lowendmac.com/lists/support.html> SuperMacs list info: <http://lowendmac.com/supermacs/list.shtml> --> AOL users, remove "mailto:"; Send list messages to: <mailto:[EMAIL PROTECTED]> To unsubscribe, email: <mailto:[EMAIL PROTECTED]> For digest mode, email: <mailto:[EMAIL PROTECTED]> Subscription questions: <mailto:[EMAIL PROTECTED]> Archive: <http://www.mail-archive.com/supermacs%40mail.maclaunch.com/> --------------------------------------------------------------- >The Think Different Store http://www.ThinkDifferentStore.com ---------------------------------------------------------------
