Intel's FB-DIMM, any kind of RAM will work for your controller?

George Macdonald wrote:
Well, they've had chipsets in the past which implemented
compatibility with both EDO and SDR rams. Then later we had chipsets
which did both SDR and DDR1 compatibility. Why should it be
difficult to put dual DDR1 and DDR2 capabilities? It detects which
type of ram it's connected to and switches to the circuitry for that
particular type of RAM.

Obviously it depends onhow big a jump there is between the technology of
the two memory channels - SDRAM and DDR-SDRAM are not too far apart in
terms of signalling - a few extra pins for source synch clocking and
a few others which were used slightly differently. OTOH we never saw
a dual DRDRAM and SDRAM chipset - too different... would certainly
require independent pins. I'm not up on the details of FB-DIMM
interfacing but I'd think it'd be different enough.

Well, there were different voltages for SDR and DDR, so it wasn't exactly
the simple jump that from SDR to DDR that you describe. Plus you needed
different sockets for each type. And in most cases you couldn't use both
types of RAM at the same time because of the voltage issue.

As for SDR and RDR together, must I remind you of the infamous Intel MTH?
Okay, I didn't say that it had to be a successful chipset (or even a good
chipset), but you did see the capability of using either type of memory at
one point in time. :-)

Yousuf Khan

"George Macdonald" wrote in
message ...

I'm not up on the details of FB-DIMM interfacing but I'd
think it'd be different enough.

George, FB-DIMM uses only a third as many pins as regular DIMMs.
Different enough? You betcha!

On Mon, 26 Apr 2004 11:38:13 GMT, "Yousuf Khan"
wrote:

George Macdonald wrote:
Well, they've had chipsets in the past which implemented
compatibility with both EDO and SDR rams. Then later we had chipsets
which did both SDR and DDR1 compatibility. Why should it be
difficult to put dual DDR1 and DDR2 capabilities? It detects which
type of ram it's connected to and switches to the circuitry for that
particular type of RAM.

Obviously it depends onhow big a jump there is between the technology of
the two memory channels - SDRAM and DDR-SDRAM are not too far apart in
terms of signalling - a few extra pins for source synch clocking and
a few others which were used slightly differently. OTOH we never saw
a dual DRDRAM and SDRAM chipset - too different... would certainly
require independent pins. I'm not up on the details of FB-DIMM
interfacing but I'd think it'd be different enough.

Well, there were different voltages for SDR and DDR, so it wasn't exactly
the simple jump that from SDR to DDR that you describe. Plus you needed
different sockets for each type. And in most cases you couldn't use both
types of RAM at the same time because of the voltage issue.

You needed different sockets because there were more pins - voltage swing
is easy if it's just a jumper on the mbrd and certainly does not disqualify
what I said.

As for SDR and RDR together, must I remind you of the infamous Intel MTH?
Okay, I didn't say that it had to be a successful chipset (or even a good
chipset), but you did see the capability of using either type of memory at
one point in time. :-)

Hmm well first it didn't work and then it had nothing to do with the
chipset - there were even DIMMs with the DRDRAM/SDRAM right on the module.
It was a "Rube" add-on and nobody with any appreciation of PC performance
would have used it.

Rgds, George Macdonald

"Just because they're paranoid doesn't mean you're not psychotic" - Who, me??

George Macdonald wrote:
On Mon, 26 Apr 2004 11:38:13 GMT, "Yousuf Khan"
Well, there were different voltages for SDR and DDR, so it wasn't
exactly the simple jump that from SDR to DDR that you describe. Plus
you needed different sockets for each type. And in most cases you
couldn't use both types of RAM at the same time because of the
voltage issue.

You needed different sockets because there were more pins - voltage
swing
is easy if it's just a jumper on the mbrd and certainly does not
disqualify what I said.

No, but as you can see people are continuously finding clever ways of being
able to support two types of RAM on a single chipset.

As for SDR and RDR together, must I remind you of the infamous Intel
MTH? Okay, I didn't say that it had to be a successful chipset (or
even a good chipset), but you did see the capability of using either
type of memory at one point in time. :-)

Hmm well first it didn't work and then it had nothing to do with the
chipset - there were even DIMMs with the DRDRAM/SDRAM right on the
module. It was a "Rube" add-on and nobody with any appreciation of PC
performance would have used it.

Like I said, it didn't have to be good chipset, nor a successful chipset,
and I guess it really doesn't have to be a pretty, professional-looking
chipset either. :-)

Yousuf Khan