Memory Designations

profdlp

Just about the time I was feeling comfortable with the move from the old-old naming convention for memory (i.e. FP, EDO) to the more logical PC-66, PC-100, etc style, the companies moved to the PC2100, etc format.

Forgive me if I'm wrong, but isn't there a direct correlation between the old naming convention and the new(est) one?
(i.e. PC2100 = PC-266, or whatever)

If I'm right about that, does anyone know of a chart showing the correlation between the two for all modern (DDR) memory chips?

If I'm wrong, could someone straighten me out?

And wasn't life easier when you just looked for a memory configuration equal to your FSB? Why was this changed?


Prof
(I must be getting old...)

Clutch

184 pin DDR DIMM

pc2100 133mhz
pc2400 150mhz
pc2700 166mhz
pc3000 188mhz
pc3200 200mhz
pc3500 216mhz

muddocktor

The only one Clutch didn't include:

PC1600 100 Mhz

Clutch

muddocktor said
The only one Clutch didn't include:

PC1600 100 Mhz

:banghead: :banghead: good call Mudd

profdlp

Thanks for the info. This is being cut-and-pasted into a document for reference purposes.

As to part II - Why did they change the name? Just to confuse people? Or is it the "more is better" philosophy, where bigger numbers seem more impressive?


Prof

Thrax

<p><strong>DDR-SDRAM:</strong><br> “Double Data Rate Synchronous Dynamic Random Access Memory.”</p><p>The unique property of DDR-SDRAM allows it to calculate twice on each oscillation of the clock, both at the top of the wavelength, then once more at the bottom.</p>
<p>What is commonly called DDR-RAM has two different naming nomenclatures.<br> The first naming scheme rates the modules in terms of maximum possible bandwidth in megabytes per second. The various types when described in this way is as follows:</p>
<p> </p><table width="28%" border="0" align="center"><tr bgcolor="#666666"><td><div align="center"><strong>Memory Type</strong></div></td><td><div align="center"><strong>JEDEC Ratified?</strong></div></td><td><div align="center"><strong>Frontside Bus Speed</strong></div></td><td><strong>Bandwidth</strong></td></tr><tr bgcolor="#999999"> <td>PC1600</td><td>Yes</td><td>100MHz</td><td>1600MB/s</td></tr><tr bgcolor="#999999"><td>PC2100</td><td>Yes</td><td>133MHz</td><td>2100MB/s</td></tr><tr bgcolor="#999999"><td>PC2400</td><td>No</td><td>150MHz</td><td>2400MB/s</td></tr><tr bgcolor="#999999"><td>PC2700</td><td>Yes</td><td>166MHz</td><td>2700MB/s</td></tr><tr bgcolor="#999999"><td>PC3000</td><td>No</td><td>187MHz</td><td>3000MB/s</td></tr><tr bgcolor="#999999"><td>PC3200</td><td>Yes</td><td>200MHz</td><td>3200MB/s</td></tr><tr bgcolor="#999999"><td>PC3500</td><td>No</td><td>219MHz</td><td>3500MB/s</td></tr><tr bgcolor="#999999"><td>PC3700</td><td>No</td><td>231MHz</td><td>3700MB/s</td></tr></table><p>The second naming scheme rates the modules in terms of the frontside bus (FSB) they run on multiplied by two. This being the case, here are the same memory types as above listed in the new scheme, and in the same order:</p><table width="28%" border="0" align="center"><tr bgcolor="#666666"> <td><div align="center"><strong>Memory Type</strong></div></td><td><div align="center"><strong>JEDEC Ratified?</strong></div></td><td><div align="center"><strong>Frontside Bus Speed</strong></div></td><td><strong>Bandwidth</strong></td></tr><tr bgcolor="#999999"><td>DDR200</td><td>Yes</td><td>100MHz</td><td>1600MB/s</td></tr><tr bgcolor="#999999"><td>DDR266</td><td>Yes</td><td>133MHz</td><td>2100MB/s</td></tr><tr bgcolor="#999999"> <td>DDR300</td><td>No</td><td>150MHz</td><td>2400MB/s</td></tr><tr bgcolor="#999999"><td>DDR333</td><td>Yes</td><td>166MHz</td><td>2700MB/s</td></tr><tr bgcolor="#999999"><td>DDR374</td><td>No</td><td>187MHz</td><td>3000MB/s</td></tr><tr bgcolor="#999999"><td>DDR400</td><td>Yes</td><td>200MHz</td><td>3200MB/s</td></tr><tr bgcolor="#999999"><td>DDR433</td><td>No</td><td>219MHz</td><td>3500MB/s</td></tr><tr bgcolor="#999999"><td>DDR466</td><td>No</td><td>231MHz</td><td>3700MB/s</td></tr></table>
<p> </p><p>To get the name of the official RAM type you take the clock cycles per second and multiply by 8 (The 8 stands for 8 bytes, or the width of the system bus currently employed on Intel/AMD systems 8 bytes is 64 bits). The processor is capable of addressing 64 bits, even though the processor is only 32 bits.</p><p>The equation example would be as follows:</p><p>FSB * 2 * 8 = x</p><p>To calculate PC2100:</p><p>133 * 2 * 8 = 2128 MB/s<br></p>

DRAM and You; A Guide to Memory Technologies
Version 2.0; Robert "Thrax" Hallock

Spinner

I imagine though that on a basic level it was also to distinguish DDR memory from basic SDRAM. As having two different types of memory (based on a modules core frequency) called PC100 and PC133 would get confusing. Not that some of you don't seem to be confused still.;)

profdlp

That's the kind of lay-it-all-out plain English answer I have been seeking for years. I have searched high and low, but haven't found anything nearly as informative.

Thanks A Bunch!:p


Prof

Clutch

I know what you mean profdlp, I hate it when you see an article trying to explain something, but in the end your still like "wtf?" I love simple, but very effective answers. Great info also Thrax

mmonnin

Where is version 2 of that memory thread of yours Thrax??

Thrax

MIA.