Dan, I should have shut my mouth! Now no one will believe me on anything. Seriously, I appreciate this info. Ah so! A bit of hardware controls this business ... your explanation supplies the best explanation to me of why pairs for interleaving probably need matching sticks. I want everyone to completely forget this episode... keep staring at this sentence and... keep on staring ... you are falling asleep... when you wake up you will not remember David Elmo's mistake ... it will be gone from your mind
:) > From: [EMAIL PROTECTED] > Subject: Re: [PCI] Add RAM to 7300 - Interleaving ?? > > At 05:01 PM +1100 03/02/2004, David Elmo wrote: >> Maybe this is a bit late... but interleaving is just a way that the Mac OS >> (at least 8.6 and 9x) can take advantage of having Ram in paired banks. > > Right idea, wrong target. :) The Mac OS (8/9/X) has no idea that > the memory is interleaved, other than to display its status when > asked. It's the Memory Controller that does it; purely in hardware. > >> Suppose you only have two sticks of Ram: Put in A1 and B1 (A2 and B2) as >> opposed to A1 and B2 or A1 and A2). > > If the sticks are matched, by type, size, *and* speed, the controller > will automagically enable interleaving on that bank. Technically, > "interleaving" is a way of accessing the DIMMs on both sides of the > clock pulse. IOW, instead of reading/writing one 32-bit word per > cycle, the controller does aword at the beginning of the cycle and > another at the end. This has the "effect" of doubling the access > speed. > >> The way the processor addresses and accesses such paired banks is quicker > > The processor itself, like the OS, is clueless. It just yells at the > Memory Controller to feed it data. The Controller manages what's in > each cache as well as main RAM. > > This is not to be confused with the Memory Manager, which is software > - part of the Mac OS. It keeps track of which (logical) blocks of > memory are allocated to which job/process/thread. > > FWIW, > - Dan. -- PCI-PowerMacs is sponsored by <http://lowendmac.com/> and... Small Dog Electronics http://www.smalldog.com | Refurbished Drives | -- Sonnet & PowerLogix Upgrades - start at $169 | & CDRWs on Sale! | Support Low End Mac <http://lowendmac.com/lists/support.html> PCI-PowerMacs list info: <http://lowendmac.com/lists/pci-powermacs.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/pci-powermacs%40mail.maclaunch.com/> Using a Mac? Free email & more at Applelinks! http://www.applelinks.com
