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DRAM, SRAM,SDRAM,RDRAm

M

mikeshn

Senior member
Which memory is faster and which is slower. In other words, can somenone list the moemory in order?
Thanks
 
Rdram = P4 use

DDR-sdram = AMD mostly with some P4 use

Sdram = pc66, pc100, and pc133 chips


I think the faster thing is a bit subjective...Therdram has it points but beside it rather large score in sythetic benchmarks it has yet seemed to have delivered in the same large real world performance...

Check out how the sis645 platform running ddr is running real real close to scores of the highly touted rdram...

Some others can get into more issue of latency and stuff and show that the rdram isn't all it has been built up to be....
 
John, isn't the on-die L2 cache on the P4, Athlon and such, also SRAM, making it the fastest(11.2GB/sec of bandwidth on the Athlon 1600+ for example)?
 
RDRAM
SDRAM
SRAM
DRAM

That's not really correct John. RDRAM, SDRAM, etc. are all types of DRAM.

SRAM is a type of RAM used for level 1, 2, and 3 caches on or around microprocessors. SRAM is a hell of a lot faster than DRAM. The disadvantage is that SRAM is very very expensive, which is why it is perfect to use in cache architecture. Level 1, 2, and 3 cache architectures usually use no more than 1MB of cache (SRAM), whereas RDRAM and SDRAM can be found in sizes of 1GB or more (DRAM). DRAM is much cheaper than SRAM, which is why it is used for RDRAM and SDRAM modules.

This is the correct order:

SRAM
DRAM (which includes RDRAM and SDRAM).
 
As said, SRAM is vastly superior to DRAM in pure bandwidth and latency. A GodSpeed has the right idea regarding SRAM.

SDRAM is the slowest DRAM type mentioned. And DDR SDRAM/RDRAM will vary in performance placement depending upon the speed grade in use, the platform, and the individual needs of the application being run.
Both have their advantages and disadvantages relative to the competition.
 
I think only DRAM needs refreshing, as the charge in the capacitors in DRAM is lost. SRAM doesn't have caps, therefore no refreshing

SRAM also have low latency, I remember modern CPU can get data from their cache in 1 CPU cycle, which the clock is of the order of GHz. To get data from DIMMs, u need something like 40 cycles, which the clock is still in MHz range, after the initial request before data is arrived in the CPU, but I am not sure if this is a problem of DIMM+NB or just DRAM

And everything as AGodspeed said

Correct me if I am wrong..
 
also, I recently learned that the reason SRAM is more 'expensive' is simply because it takesalot of space on the die to achieve the same amount of memory as DRAM. I think it takes like 12 transistors to do the same as 1 transistor and capacitor when comparing SRAM and SDRAM.

which is why the 1T SDRAM on the Gamecube is interesting, becuase AFAIK, it has the speed capabilities of SRAM (low latency), without all the transistors.. I can't remember exactly on this part, but basically that's why we don't use SRAM chips 🙂
 
I wonder if 1T SRAM will ever make it to us as consumers. I'd love to get me a 256mb stick of that running at processor speed in my computer 😀
 
More types of (now obsolete) ram to toss in for fun:

those SIMM sticks: EDO, and fast page mode. Are these also types of DRAM? Or are they some other type of stuff?
 


<< those SIMM sticks: EDO, and fast page mode. Are these also types of DRAM? Or are they some other type of stuff? >>



Not knowing all the detail, I am sure those are all DRAM

The differences between EDO, FPM, SDRAM(s), RDRAM are their bus widths, operating frequencies......, and most importantly the protocol used by the memory controller in the NB talk to these modules
 
Don't forget, while RDram scores higher in terms of pure bandwidth, remember it's got a higher latency than DDR or SDRAM types...
 
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