MEMORY

[Guest]

Since this is the only board where ppl are responding...i"ll ask it here. What do the numbers mean that are advertised in the ram specs....fir example.....(32x64) or (32x72)...... anyone?

 

[Guest]

take a calculator and start counting

32*64=2048

64 vs 72 = 8, sounds like the extra 8 bit required by ECC ram, e.g. Error Checking and Correction

2048 probably is 2MB per chip, usually 8 chip per side, therefore = 16MB only, hmmm, are those old rams or new rams?

or is it more than 8 chip per side?

obviously I don't know what I am talking about !!!
eheheh but was fun figuring things abit!

Soemthings wrong, ask other experts!! hehehe



Best regards
cx5

 

[Guest]

If I am not mistaken this is the number of MB x number of pins. ie 64 pins vs 72 pins. Modules have different pin counts depending on their type

 

[Guest]

Well that's the part i dont' understand......that (32x72) actually came from a 168 pin PC100 256mb ram spec sheet. Anyone?

 

[Guest]

Alrighty then......

 

[Guest]

?Go figure?

 

[Guest]

Well, I just went out and looked at some DIMM configurations. Just using some math it appears that the first # represents the density of 1 of 8 values on a dimm. I don't know exactly what the 64 stands for but would be interested if anyone does. Sooooo.....
2x64=16MB DIMM (2x8)
4x64=32MB DIMM(4x8)
32x64=256MB DIMM(32x8)

 

[Guest]

Another thing is that the 64 changes to a 72 if it's ECC...(at least at what i'm looking at right now)

 

[Guest]

Yep...I think FCChin was pretty much right on target with the ECC stuff. 8 extra bits.....

 

[Guest]

He had a lucky guess..hehe

 

[Kelledin]

I would think the second number (i.e. the 64 in 2x64) refers to Mbit per actual memory chip. Thus 2 chips on a SIMM/DIMM at 64Mbit apiece = 128Mbit; 8 bits per byte, 128Mbit = 16MB.

Of course, this is defied by the fact that ECC modules actually have an extra memory chip, instead of having an extra 8 Mbits per chip.

Could the 2 refer to row address, while 64 refers to column address? I believe memory accesses on SIMMS/DIMMS do work by row-and-column at a low level, even though at a high level, software just sees one big long array of bytes.

Kelledin
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