> Len Warner <[log in to unmask]>

>Len Warner has stated:
>Can we go back to the question and relate the answers
>to the memory simms - is there a microelectronics
>expert among our readers who can tell us:

>a) what it is about EDO that makes it incompatible with FPM
>   (e.g. timing or pinout differences)
>b) whether, as asked, there is 'newer' EDO memory
> that is compatible with FPM, or even whether
>   this is a possibility or a meaningful question?

To go back to the original question that I asked, I would like to upgrade the
memory on an older Packard Bell system.  The system has an AMI MB and BIOS.
The chipset on the MB is an Intel Neptune chip set 82433NX (LBX), 82434NX (PCMC)
, and 82378ZB (SIO.G).

The User Guide [published 8/3/94] for the computer states on p. 5-24: " 2. You
should use 72-pin 60, 70 or 80 ns fast page mode DRAM SIMM's.

Information in Packard Bell's WEB site states for this system PB550:

Specifications

1. SIMM speed must be 70ns or faster.
2. The SIMMs are 72-pin and can be x32 or x36. The motherboard design does not
require parity
checking, hence the cheaper x32 SIMMs can be purchased. The motherboard will
not use EDO,
only Fast Page Mode SIMMs will operate correctly in this motherboard.

And yet Scott Mueller's Upgrading and Repairing PC's states on page 803
paragraph 2 of the 8th edition, "You can install EDO memory in older systems
that do not support it because EDO is backward-compatible with standard (called
fast page mode) memory."

And Stephen Bigelow in TroubleShooting & Repairing PC Drives & Memory Systems -
Second edition states on page 98 par. 2, "You should realize that EDO RAM can
be used in non-EDO motherboards, but there will be no performance improvement."

So who is right??  I would prefer buying EDO memory in case I would upgrade the
MB in the future to a chip set that will support it.  But yet if the EDO will
not really work in the current system and in fact I do need FPM memory then I
will purchase that for the time being.

Thank you in advance for any advice or hands on experience that you can share
with me.

Sincerely, John