If Memory Serves

Is it time to upgrade your computer's memory?
Magazine Contributor
8 min read

This story appears in the April 1997 issue of Business Start-Ups magazine. Subscribe »

Just a few years ago, the conventional wisdom said that upgrading your existing PC system often made sense. You could easily add a few years of life to your system by upgrading your , CPU, memory or graphics adaptor. But with today's exceedingly fast-paced changes in computer technology and free-falling prices, that no longer holds true.

"You can get a system for $1,800 this year that cost $4,000 a year ago," says Jim McGregor, senior analyst for In-Stat, a market research and consulting company in Scottsdale, . "So now I'd say, `Get as much system as you can, use it as long as you can, and then move on to a new system."

McGregor cites just two exceptions to that rule: adding memory or a faster modem. Modems were spotlighted in last month's "Business Bytes"; this month, we focus on what adding memory, or RAM, can do.

RAM temporarily stores programs, data and processed information in memory cells as it moves to and from the processor, video card and other peripherals. If you don't have enough high-speed RAM, your computer will temporarily store your data or applications in virtual memory--meaning it uses your hard drive. Because hard drives use mechanical (rather than electronic) methods to store and retrieve information, using virtual memory significantly slows down your system. Conversely, adding RAM can vastly improve application speed.

The good news for potential buyers is that memory prices have been plummeting over the past year--you can currently get a RAM upgrade for about $6 or $7 per megabyte.

When To Upgrade

Memory is always on every techie's list of top upgrades. But that doesn't mean you should automatically add memory to a slow machine. "If your system is less than a 486, sell it," advises McGregor. "It's technologically incompatible with Windows 95."

Similarly, if you have a brand-new machine, you probably won't need to upgrade memory, either. Most computer manufacturers have begun loading new machines with 24MB or 32MB RAM, which is more than adequate for most requirements. It's certainly more than today's applications can use, and it will probably take a year or two before typical applications start requiring that much memory. Even then, probably only the traditionally memory-hungry applications such as games, multimedia or videoconferencing will require additional memory.

Where you may start needing more memory is if you habitually use several applications at one time in different windows. For the most part, memory is a good upgrade. If you have an older Pentium model, or if you have a 486 with 4MB to 8MB RAM, you can probably get another year out of it.

Do It Yourself?

Determining which type of RAM you need, however, isn't easy. With so many types, in many speeds, sizes and capacities, it's easy to buy the wrong kind.

The type of RAM you'll be upgrading is called DRAM (Dynamic RAM). If you own a brand-name PC, upgrades will be relatively straightforward. Call a reputable memory vendor, and tell them your PC's brand and model. The company should be able to find RAM modules that fit your system.

But if you have a no-name clone or want to buy your memory at a computer superstore, you'd better know what you're doing. Here are the factors you need to consider:

  • SIMMs and DIMMs: First, you need to know whether your computer uses SIMMs (single in-line memory modules) or DIMMs (dual in-line memory modules). A SIMM or DIMM is a plug-in board with a number of RAM chips that fits into a socket on the motherboard. SIMMs come in 30- or 72-pin varieties, while the newer DIMM design has 168 pins. If you have a 486 PC, you're probably using SIMMs with either 30 or 72 pins. Pentium PCs usually use 72-pin SIMMs or 168-pin DIMMs.

  • Pins: These are tiny vertical gold bars at the bottom of the memory module. The easiest way to find out how many you have is to remove the PC's cover and measure the size of the module. A 30-pin SIMM is just over 3 inches long, a 72-pin SIMM measures a bit over 4 inches long, and DIMMs are about 5 inches long.

  • Memory speed: Most of today's PCs use either 60- or 70-nanosecond (ns) RAM. To determine which speed your computer uses, consult your PC's manual or technical specifications, or ask your vendor. If your PC requires 70ns RAM, you can use the faster 60ns chips, although you won't get any speed advantage. Don't buy RAM that's slower than required because it won't work in your system.

  • Memory banks: When you add RAM modules to your PC, you'll need to fill an entire memory bank. On some PCs, one bank can hold four SIMM slots; on others, two SIMMs or one DIMM fill up a bank. If you can't tell by looking at the motherboard, check its documentation to determine what constitutes one memory bank in your PC. If your memory banks are full, you'll need to replace your existing RAM with higher-capacity SIMMs or DIMMs.

Remember, you can't mix memory of different capacities, such as 1MB and 4MB SIMMs, in the same bank. You can, however, mix them in terms of having, say, one bank full of 1MB SIMMs and another bank full of 4MB SIMMs.

The Future Of Memory

One of the major problems with all RAM used in today's systems is that it can't keep up with processor speeds. For example, you may have a CPU that can run at 200 MHz but memory that runs at only 100 MHz. That causes bottlenecks in your system, and you won't get the performance gains you'd expect from upgrading to a faster CPU.

To solve this problem, vendors are working on new ways to speed up DRAM technology. Again, you need to know what your system supports; you won't get any additional performance gains from high-speed RAM if your system can't support that particular type of RAM. Following is an overview of some of the best RAM technologies out there--and what's coming up next.

  • Fast Page Mode (FPM) DRAM was the type of RAM used in older Pentium systems. It's an improvement over older forms of DRAM because it accesses data in the same row faster. If data needed is in the same row as the previous data, the memory controller doesn't have to repeat the row location; it only needs to indicate the next column location. Typical FPM DRAM speeds are close to 30 MHz.

  • Extended Data Output (EDO) DRAM reduces the amount of time it takes to read data from memory by transferring data on both the uptick and the downtick of the clock cycle rather than on just one-half of the cycle. It runs at about 50 MHz. This type of fast memory has been added to most Pentium and Pentium Pro systems sold in the past 12 months.

  • Burst EDO (BEDO) DRAM is an innovation that allows a "burst," or series of data, to be transmitted from memory with a single request. It runs at about 66 MHz.

  • Synchronous RAM (SRAM) synchronizes memory speed with the speed of the internal processor. With current technology, SRAM runs at 100 MHz. While SRAM is starting to appear in some systems, production is not yet high enough to meet demand. As chip production increases, however, SRAM is likely to become the dominant RAM technology over the next six months to a year.

  • RDRAM or RAMBUS DRAM is a DRAM chip from Rambus Inc., a memory chip manufacturer. RDRAM will probably become the new standard in the next two years because it has the support of Intel Corp., the largest CPU manufacturer for PC systems. When this type of RAM becomes widely used, it should support high-speed transfer rates of 1.3GB, which will keep up with PC clock speeds. Currently, RDRAM is used only in some game machines and PC graphics applications.

If anything can improve your system's speed and life span, it's RAM. With these basics, you should know enough to upgrade your system.

In A Flash

Another type of memory you may see mentioned in the trade press these days is flash memory. Flash memory is a hybrid technology that works somewhat like RAM and somewhat like a . It stores data in memory cells like RAM; but unlike RAM, the data stays in memory after the power is turned off.

Because flash memory has a limited life span and storage space, and must be erased in blocks of data rather than single bytes like RAM, it will never replace RAM. But compared with hard drives, flash memory has several advantages. It has no moving parts, so it has a higher tolerance for shock, vibration, extreme temperatures and harsh environments. Flash memory cards are also smaller and faster than hard drives.

Thanks to these characteristics, flash memory cards are being used as portable hard drives in rugged situations. They're also used in digital cameras, cellular phones, audio recorders and scanners to store images and voice data; in networking devices to store microcodes and instructions for transferring data; and in printers and print servers to hold fonts or frequently used graphics.

Cheryl J. Goldberg is a former editor of PC Magazine and has reported on the computer industry for more than 14 years. Write to her in care of Entrepreneur, 2392 Morse Ave., Irvine, CA 92614. You can also reach her via CompuServe at 70641,3632.

Contact Sources

In-Stat, 7418 E. Helm Dr., Scottsdale, AZ 85260, (602) 483-4460;

Kingston Technology, (800) 337-8410, (http://www.kingston.com).


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