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EMS HSDRAM : Tomorrow's Memory Today?

If you are reading this article, you probably already know that SDRAM is the type of high speed memory used in almost all PCs shipping today. However, you might be wondering what the next big thing will be, or what the best is available today.

By now, you have probably figured out that HSDRAM is just a synonym for high-performance SDRAM. What justifies an H in the name? An HSDRAM chip must have low latency. That means that it basically has a low hesitation factor when asked to remember something, to put it into simple terms. Latency factor is determined by access time, measured in nanoseconds (a billionth of a second, and abbreviated as ns). With computer systems accessing memory at extremely high rates, a lower latency can give a performance edge.

Enhanced Memory Systems was kind enough to send me a PC133 HSDRAM for review. When I received the chip, I was really impressed with it physically. It looked almost too good to go into my computer, as it seemed like something meant for a workstation or a server. The physical size was impressive, but for some people, this might be a drawback if they have a cramped system or a large heatsink. The chip is also made of high-quality, 6-layer PCB, and more layers can increase stability of both memory chips and motherboards.

Specificaitons
  • Industry Standard PC133 SDRAM DIMM
  • Fast 4.6 ns Clock Access Time
  • Lower Latency Than Other PC-133 Modules (3:2:2) @ 133 MHz
    • CAS Latency = 3
    • RAS to CAS Delay = 2
    • Precharge delay = 2
  • High Quality 6-Layer PCB for System Stability
  • Uses 64Mbit Enhanced Memory Systems Chips for Consistent Performance
  • Overclock Existing PC Systems to 133 MHz
  • Ideal for High Performance 133 MHz Bus Speed Systems
  • On-board Serial Presence Detect (SPD

If you are looking for some performance details, I found it best to just provide their latency information. My running benchmarks against standard PC133 memory yielded inconclusive results, so it became obvious that I would be unable to point out any differences with my own numbers since my hardware is not capable of creating a performance difference.

The table below summarizes the results of several independent evaluations on various Intel BX system boards. Each frequency is associated with the programmed CAS latency and the number of modules installed to achieve successful operation.

A fast access time of 4.6 ns provides the timing margins required to achieve these operating frequency and system loading (number of DIMMs installed) statistics.

Operating
Frequency
CAS Latency
64MB DIMMs
Installed
128MB DIMMs
Installed
150
3
2
2
143
3
2
2
138
3
3
2
133
3
4
3
133
2
2
2
125
2
3
2
112
2
4
4
100
2
4
4

First of all, I should explain CAS. It stands for Column Access Strobe Latency, and a lower CAS number should mean a performance increase. From other reports I have read from various external sources, going from a 3 to a 2 yields about a 5% increase in performance on high-end applications.

More importantly, a lower CAS means better stability. If we look at a common combination here, 2 x 64 MB @ 133MHz, we get a latency of 2. This means that we have what is called a 2-2-2 combination, and is something that will give you an extra performance boost.

Keep in mind, you are only going to get this if you have two 64 MB or 128 MB EMS chips in your computer, and leave the other slots empty. However, if you are looking to totally upgrade your memory, getting two 128 MB HSDRAM chips from EMS would be a solid choice. It would definitely give you a more stabile, and more efficient system.

If you want to overclock your system using a motherboard frequency above 133 MHz, you will no longer be able to obtain the 2 CAS, but you will still be likely to have a solid system up to 150 MHz. I only wish I had a motherboard available to test the EMS memory above 150 MHz, but if I do in the future, I will be sure to update this article and let everyone know the results.

OK, we have determined that this is very good memory, now how much will it set you back? Currently, one 128 MB chip runs $150, a small premium to standard SDRAM chips from other manufacturers. So if $300 sounds reasonable for 256 MB of some of the best memory on the market, you should probably go for it.

HSDRAM will work in any system that can use standard SDRAM. However, you will see maximum benefit only in systems with a high motherboard frequency. So, if you currently (or will) have a motherboard running at 133 MHz or above, you should seriously consider HSDRAM.

So, is HSDRAM the memory of tomorrow? Well, some things called DDR and RDRAM are, but HSDRAM is clearly the best memory of today, and should be a viable, stable solution for a long time.

Eric Murphy
00/04/18





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