i d9c777369436c038 by Unknown

Author:Unknown
Language: eng
Format: mobi
Published: 2009-03-25T04:54:49+00:00

Part 3 ➤ Third Quarter: Taking Everything Apart wants to do is further evolve existing DIMM technology by adding a separate clock timed at 200MHz, synchronizing that clock with the system bus clock, then utilizing the double-data rate trick. The Consortium also wants

to try Rambus’ idea of mixing and matching compo-

nents (perhaps not with the zero memory module

thing, though), so you can have a 128MB DIMM and

a 64MB DIMM sitting side by side.

Note

Buying the Right Kind of

This book will be in print for a

RAM

little while. During that time, SL-

Determining what specific module packaging your

DRAM components, and chipsets

motherboard requires is more difficult by a long shot

that support them, will likely be

than actually installing the modules themselves. You’ll

made available on the open

need to do some math, so get out your calculator.

market. There will be one more

(You remember calculators, don’t you? Those things

type of DIMM to contend with.

you find in your Windows Start menu under

Accessories? )

At the time of this writing, the market price for ordinary DRAM was averaging 22.6¢

per megabyte, based on the price of the “benchmark” 128MB unbuffered SDRAM.

There was a time when I used to say RAM prices varied like the price of stocks, and you should wait for the right time to jump in and buy, then buy big. I don’t say that anymore. Whatever forces could possibly converge to drive the price of RAM up, don’t appear to be converging anytime between now and 2003. If you’re thinking about waiting for the right time … don’t.

Depth, Width, and Speed

Before I go back to talking about Rambus, let me return for a moment to the way things generally work in the world of memory. The Pentium series is a 64-bit processor, which means the width of its data bus is 64 bits. Keep that in mind for a moment. Now, the contents of a DIMM (or SIMM) memory module are arranged in rows and columns, but not exactly the same way as the chipset perceives it (the “perfect square” analogy). Instead, all the chips that make up a DIMM put together have a set number of rows of bits. The number of bits in each row may or may not be 8, even though the old rule still applies that there are 8 bits in 1 byte. A DIMM module is registered by three numbers:

➤ Depth refers to the total number of megabits that comprise one column of storage within the module. A megabit is 1,048,576 bits.

➤ Width refers to the number of bits that comprise one row of storage within the module. Multiply depth by width and divide the product by 8, and the result will be the module’s memory capacity in megabytes.

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