Hello Hamish!

Saturday March 11 1995 18:32, Hamish Moffatt wrote to Joseph Hanna-rivero:

 >> Pentium 66 system with:

 >> 4MB 72 pin RAM,

 HM> Honest question; the Pentium should have a 64 bit bus, so how come you can
 HM> get away with 32 bits of RAM only?

Seems you need to go and take a read of basic Pentium specs. All RAM in use
in PCs is only 8 bit (or 9 bits if it has parity). A byte is 8 bits last I
looked. A Pentium has 64 bit pathways internally but is more or less only
32-bit on the outside.

The only reason we can use 60/70 ns RAM on such FAST processors is due to a
technique known as paged/interleaved memory access. This method needs a
particular shape/size playing field to work on. This is why 30 pin boards
(386DX +) required banks of 4 SIMMs. 4 x 8 (bits) = 32 bits width of RAM.
72 pin RAM rolled (through size reduction) all that into one module so you
can now insert single modules instead of having to fill 4 at a time hence
virtually total freedom over memory configuration. Only limitation is that
there are now banks of 2 which although can be filled with only one module
if desired, when they are both used, they must contain the same size
modules.

Regards,

    Matthew

--- GoldED/386 2.42.G0615