Questions about DDR RAM

[Nate Edel]

We were talking about memory.

Yes; all DIMMs are memory, but not all memory comes in DIMMs.

Memory comes in lots of widths, and no more explicitly applies to DIMMs than
to the individual chips on the DIMMs or soldered to a board.

We were talking about memory, not processor implementation. Do you
have an example of an x86 processor with a wider than 64bit data path
to the DIMM (ignoring dual channel for the moment, which is simply
two DIMMs)?

x86? No, although you're changing the goalposts, and I did say it was a
quibble. The AMD dual channel implementation *IS* a full 128-bit path to
memory, just split between two DIMMs.

I have no idea what IBM uses for memory in their very high-end stuff, but
that's not x86; even high-end stuff from Sun, etc, tends to just use
multiple channels breaking down to DIMMs.

We were... Do you really have parity/ECC on graphics cards?

Not on consumer stuff.

It's been a *long* time since I've paid attention to high-end workstation
graphics boards. It would be pretty implausible on consumer stuff or on
today's "derived from consumer" FireGL or Quadro boards.

Anyone have an old IBM PGA board from the mid-80s? I'd be quite surprised if
that DIDN'T have parity.

 

[daytripper]

]

Anyone have an old IBM PGA board from the mid-80s? I'd be quite surprised if
that DIDN'T have parity.

Really?
Why would *anyone* actually want parity on graphics memory?

/daytripper
(who's been surprised before...but I don't think it's happening this time ;-)

 

[krw]

Yes; all DIMMs are memory, but not all memory comes in DIMMs.

Memory comes in lots of widths, and no more explicitly applies to DIMMs than
to the individual chips on the DIMMs or soldered to a board.

Oh, good ****ing grief Gert! I know the Democrats in the Senate
don't believe it, but CONTEXT MATTERS. How long have DIMMs been the
only memory used?

x86? No, although you're changing the goalposts, and I did say it was a
quibble. The AMD dual channel implementation *IS* a full 128-bit path to
memory, just split between two DIMMs.

No, I'm not moving goal posts (look at the name of the NG). You're
being an pedantic ass.

I have no idea what IBM uses for memory in their very high-end stuff, but
that's not x86; even high-end stuff from Sun, etc, tends to just use
multiple channels breaking down to DIMMs.

I do know. Registered DIMMs, in fact. Anything else would be
stupid. Your point is?

Not on consumer stuff.

Not on *ANY* stuff. Can you think of *one* reason to spend a nickel?
Add the complication?

It's been a *long* time since I've paid attention to high-end workstation
graphics boards. It would be pretty implausible on consumer stuff or on
today's "derived from consumer" FireGL or Quadro boards.

Anyone have an old IBM PGA board from the mid-80s? I'd be quite surprised if
that DIDN'T have parity.

I'd be *very* surprised if it did (in fact I know they didn't). I
have *NEVER* seen parity on graphics memory. WTF would anyone waste
money on that? What is the gain, one off-color pixel? Come on, stop
running away from your silliness.

 

[Nate Edel]

]

Anyone have an old IBM PGA board from the mid-80s? I'd be quite surprised if
that DIDN'T have parity.

Really?
Why would *anyone* actually want parity on graphics memory?

Framebuffer? Probably doesn't matter, since it's being rewritten
continuously.

That said, there's more to graphics memory ... and for some apps, you could
well want ECC any time the graphics memory contains uploadable code.

I was under the impression modern 3D stuff does, but it may always get the
instruction stream pushed to it? See also attempts to use the GPU as a
general vector processor for non-video use.

That said...

According to Wikipedia, what I was thinking of was the "PGC" (Professional
Graphics Controller) not the PGA, here's the article.

http://en.wikipedia.org/wiki/Professional_Graphics_Controller

It was a big ol' nightmare of a card, and basically a CAD accelerator. It
had its own memory and processor. That said, the picture here looks like
it's got banks of 8 chips: http://www.seasip.info/VintagePC/pgc.html so I
am probably wrong in my guess.

I've got a couple of old DEC systems with framebuffer cards, and could dig
those out, but they're relatively low-end early 1990s ones.

 

[Nate Edel]

Oh, good ****ing grief Gert! I know the Democrats in the Senate
don't believe it, but CONTEXT MATTERS. How long have DIMMs been the
only memory used?

The only memory used for what? Main-memory on mainstream PC motherboards,
it's probably close to ten years since 72-pin SIMMs went out.

Other uses? Never. There are plenty of other sorts and uses of memory.

They may or may not use ECC. That wasn't the point I was making.

No, I'm not moving goal posts (look at the name of the NG). You're
being an pedantic ass.

A) This thread is being posted to several newsgroups:
alt.comp.hardware.hardware.homebuilt
alt.comp.hardware
alt.comp.hardware.pc-homebuilt
comp.sys.ibm.pc.hardware.chips
... and in practice, the last (where I'm reading) has plenty of
broader-ranging discussions.

B) Second, see above quoting my original post: I started by noting that it
was, indeed a quibble. You're the one objecting to my clarification,
which was a minor point. If that's "being an pedantic ass", deal with it.

I do know. Registered DIMMs, in fact. Anything else would be
stupid. Your point is?

So the z-series and similar uses DIMMs? Fair enough.

Not on *ANY* stuff. Can you think of *one* reason to spend a nickel?
Add the complication?

Raw framebuffers have no need for parity/ECC. Graphics memory these days is
hardly just a raw framebuffer.

I'd be *very* surprised if it did (in fact I know they didn't). I
have *NEVER* seen parity on graphics memory. WTF would anyone waste
money on that? What is the gain, one off-color pixel? Come on, stop
running away from your silliness.

So it only ran out of the ROM routines?

 

[Frank McCoy]

Yes; all DIMMs are memory, but not all memory comes in DIMMs.

Memory comes in lots of widths, and no more explicitly applies to DIMMs than
to the individual chips on the DIMMs or soldered to a board.


x86? No, although you're changing the goalposts, and I did say it was a
quibble. The AMD dual channel implementation *IS* a full 128-bit path to
memory, just split between two DIMMs.

I have no idea what IBM uses for memory in their very high-end stuff, but
that's not x86; even high-end stuff from Sun, etc, tends to just use
multiple channels breaking down to DIMMs.


Not on consumer stuff.

Not running code, but pretty much only data, there really isn't much
*need* for ECC on graphics cards, as long as the error isn't obvious and
permanent. (There are tests for that.) Who cares all that much if a
pixel changes color slightly?

 

[krw]

The only memory used for what? Main-memory on mainstream PC motherboards,
it's probably close to ten years since 72-pin SIMMs went out.

In PCs, dipstick! Has another DRAM form factor been used in the last
decade for anything (other than directly mounted)?

Other uses? Never. There are plenty of other sorts and uses of memory.
Examples...

They may or may not use ECC. That wasn't the point I was making.

I'm not sure what point you're making anymore, but you're looking
rather foolish dancing.

A) This thread is being posted to several newsgroups:
alt.comp.hardware.hardware.homebuilt
alt.comp.hardware
alt.comp.hardware.pc-homebuilt
comp.sys.ibm.pc.hardware.chips
... and in practice, the last (where I'm reading) has plenty of
broader-ranging discussions.

....and those groups are involved with?

B) Second, see above quoting my original post: I started by noting that it
was, indeed a quibble. You're the one objecting to my clarification,
which was a minor point. If that's "being an pedantic ass", deal with it.

Dance, dance, dance.

So the z-series and similar uses DIMMs? Fair enough.

Yes. Anything else would be sorta pointless, no?

Raw framebuffers have no need for parity/ECC. Graphics memory these days is
hardly just a raw framebuffer.

Dance some more. References to this ECC graphics memory, please!

So it only ran out of the ROM routines?

Huh? You've danced right off the edge!