On Sat, 23 Nov 2002 00:29:32 -0500 Byron Desnoyers Winmill <[EMAIL PROTECTED]> wrote:
> On Tue, Nov 19, 2002 at 12:17:20PM -0800, Jeff > Andrusin wrote: > > I attempted to switch 2 4mb chips from my > LCII to my IIci > > I'm fairly certain that the IIci requires > memory to be installed in banks > of four. The memory in those banks should be > of the same size and speed. > > Most 32-bit machines require 4 banks of 30-pin > SIMMs. Just to clarify: the same size/speed for each bank requirement is not an attribute of being a 32-bit machine, it's just the design of the memory interface. For machines requiring same size/speed chips on each bank, it's because [the contents of] one byte of memory is spread out among those banks. Geek ON; Example: if the unsigned 8-bit value 198 ($C6, B11000110) is at memory location 4096 ($1000), then the contents of the two bits (8 bits / 4 banks = 2 bits) on each bank corresponding to that address are: bank 0: 2 bank 1: 3 bank 2: 1 bank 3: 0 and are mapped thusly: B 1: bank 0, address $1000, offset 0 1: bank 1, address $1000, offset 0 0: bank 2, address $1000, offset 0 0: bank 3, address $1000, offset 0 0: bank 0, address $1000, offset 1 1: bank 1, address $1000, offset 1 1: bank 2, address $1000, offset 1 0: bank 3, address $1000, offset 1 The sequence might actually be bank 3, 2, 1, 0, depending on how the *bits* are ordered in memory, but this is basically the reason why there's the same size/speed memory requirement. For (*LOTS*) more information on hardware design, and other cool stuff like that, check out <arstechnica.com> [not at all affiliated, other than being an avid reader] Geek OFF; p8r -- System6 is sponsored by <http://lowendmac.com/> and... 123Inkjets.com <http://lowendmac.com/ad/123inkjets.html> Support Low End Mac <http://lowendmac.com/lists/support.html> System 6 Heaven <http://www.euronet.nl/users/mvdk/system_6_heaven.html> System6 info: <http://lowendmac.com/lists/system6.html> 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/system6%40mail.maclaunch.com/> --------------------------------------------------------------- >The Think Different Store http://www.ThinkDifferentStore.com ---------------------------------------------------------------
