ASUS P2B MB and single sided stck of 256 meg of memory...

[Portia]

It appears that 256 single sided memory when inerted only show a tolal
of 192 megs of mem (64 meg also added)...has anyonethis problem? did a
later bios upgrade correct it.

manual only does up to 128 meg of single sided support and 256meg of
doble sised supported.

any ideas would be much appreciated. thanx

 

[Roger Hamlett]

It appears that 256 single sided memory when inerted only show a tolal
of 192 megs of mem (64 meg also added)...has anyonethis problem? did a
later bios upgrade correct it.

manual only does up to 128 meg of single sided support and 256meg of
doble sised supported.

any ideas would be much appreciated. thanx

The 256MB stick, is only being seen as 128MB (plus the other 64MB=192MB).
This is an addressing limitation of the chipset (not fixable in the BIOS).
This is why the manual lists the sizes it does. A double sided 256MB
module will work fine.

Best Wishes

 

[Paul]

The 256MB stick, is only being seen as 128MB (plus the other 64MB=192MB).
This is an addressing limitation of the chipset (not fixable in the BIOS).
This is why the manual lists the sizes it does. A double sided 256MB
module will work fine.

Best Wishes

Crucial.com will sell you the correct memory, via their database
of motherboards. That is where I got my 256MB sticks.

HTH,
Paul

 

[Paul]

(e-mail address removed) Wrote: > It appears that 256 single sided memory when inerted only show a tolal
Roger is correct, the single-sided stick of memory uses PC133addressing,

not PC100. You require the latter type. This type of memoryis more
expensive, but as mentioned you can find an exact match for
yourmotherboard at several sites or you can buy used from a place like
Ebay.Just be sure it is double-sided, and that should work fine.

- Leo-- Leomania

Uh, the addressing has nothing to do with the speed. In many cases
now, the same chips are used to build PC100 and PC133 modules.

The addressing refers to the multiplexed address bus on the memory
chip. There is a row and a column address, and they take two
cycles to transfer to the memory chip. The Northbridge has a limited
number of address signals, and also has a limited set of address
patterns to use to drive the memory. The patterns I am referring to,
are which processor address bit, maps to which multiplexed addressed
signal.

(Page 107-108 440BX datasheet)
ftp://download.intel.com/design/chipsets/datashts/29063301.pdf

The chipset was never intended to drive 256MB modules, but there
does appear to be a mode that works. The thing is, there aren't
enough modes to cover all the ways of making a 256MB SDRAM module.
That is why some modules will work, and some will only have half of
their memory detected.

For example, I could stick 4x 16Mx16 memory chips on each side
of a memory module. It would be double sided, but it wouldn't work.
A double sided module with a total of (16) 16Mx8 chips appears to
work - and that is what I bought from Crucial for my P2B-S.

HTH,
Paul

 

[Barry Watzman]

The manual is right. The chipset doesn't recognize high-density dram
parts of the type used (required) to make a 256 meg single sided module.

 

[Barry Watzman]

PC100 and PC133 are speed ratings, and have nothing to do with
addressing. The comments are accurate about single and double sided,
but they have nothing to do with PC100 and PC133.