An article on computer terminology in yesterday's Fast Forward section should have said the realistic minimum for a hard drive's memory capacity is six to eight gigabytes. (Published 11/20/99)

Processor: The "clock speed" of a computer's microprocessor is one of the most frequently cited figures in advertising--and also one of the least relevant when it comes to your actual experience. If you're not seriously into computer games, don't live in graphics programs such as Adobe Photoshop, and don't drive a spreadsheet or database program all day long, any current machine's processor will be fast enough. It's the other parts of the system that can make your computing experience more or less miserable, such as the . . .

L2 cache: This small area of high-speed memory rides shotgun with the processor and stores recently accessed data and instructions. Within a given processor line--Pentium III, Celeron, Athlon, G3 and so on--more is better, but comparisons aren't so straightforward between different processor designs, as each wires the cache to the processor in a different way. L2 (short for "Level 2") cache is often much less important than the amount of . . .

Memory: You need at least 64 megabytes of random access memory (RAM). Period. Getting more preinstalled is better, because plugging in additional memory chips is often expensive and difficult. Those fond of computer games should pay extra attention to another sort of memory . . .

Video memory/graphics accelerator: The computer's graphics circuitry uses an extra stash of memory to store video data. Eight megabytes is the effective minimum if you want to play any computer games, ever. Most computers also include a graphics accelerator of one kind or another, which is also a requirement for most current games, which year by year grow increasingly intolerant of hardware below their specifications. Like, say, the . . .

Hard drive: The realistic minimum here goes up year by year, but 6 to 8 megabytes will suffice for lots of people. For others--those who want to collect MP3 sound files, install lots of games or edit pictures and video--it's not even close enough. Math warning: Computer manufacturers usually pad their hard-drive sizes by redefining a gigabyte as 1 billion bytes, instead of the correct figure, 1,073,741,824 bytes. Divide 10 billion bytes by one billion, and the drive suddenly gains an additional 700 megabytes of data. This is a particularly lame form of hucksterism, as both Win 98 and the Mac OS use the real figure in their own displays; we use corrected numbers in our reviews. Fortunately, no such trickery prevails in the marketing of the . . .

CD/DVD-ROM drive: This is essential for installing any software on a computer and for playing audio CDs; fortunately, both activities don't require a particularly fast drive (a 24x or 32x model, meaning 24 or 32 times as fast as the first-generation models of seven or eight years ago is perfectly adequate). A DVD-ROM drive is much less essential, given that (a) very little software is available in that format, and (b) watching DVD movies on a 15-inch monitor, sans surround-sound, is an exercise in frustration. Some manufacturers also include a CD-RW drive ("CD burner" in the vernacular), which can record computer data or music onto CDs. That's a worthwhile option if you plan to spend a lot of time downloading songs with a . . .

Modem: 56-kbps "v.90" modems (so named after the International Telecommunications Union standard governing their operation) are standard equipment on computers; they actually max out at 53 kbps when downloading data, and only 33.6 kbps when uploading data. If you're interested in high-speed Internet access, the more important component is . . .

Ethernet: An Ethernet port, running at either 10 megabits per second (mbps) or 100 mbps, is how most cable-modem and DSL (digital subscriber line) Internet connections are connected to a computer. You can also add an Ethernet port later on if you have a free . . .

Expansion slot: Most desktop computers include two or more of these slots, which accomodate various expansion cards. You'll see two kinds of these slots: PCI (peripheral component interconnect) and ISA (industry standard architecture, found only on PCs). The former are the ones that count; the slow, obsolete ISA slot mostly wastes space and Windows system resources. An open expansion slot lets you add such new capabilities as faster 3-D graphics or additional . . .

Expansion ports: You'll use these to plug in peripherals such as a printer, scanner, digital camera or a Palm handheld's cradle. Apple has standardized on USB (universal serial bus) ports, which handle most current peripherals, and FireWire (also known as i.Link or "IEEE 1394"), which is essential for connecting digital camcorders and will be handy for linking such high-speed devices as CD burners. PC manufacturers, however, include a more diverse, more confusing mix of ports, usually one or more serial (used for modems and some digital cameras), one parallel (printers and scanners), two USB, one joystick and a pair of "PS/2" ports for the keyboard and mouse. On the plus side, you can connect a device made in 1989 to your 1999-model computer; on the minus side, all this complexity makes it more likely that a perplexed home user will need to resort to the company's tech . . .

Support: Often the least satisfying part of the entire home-computer experience, as many computer manufacturers use their tech-support lines to blame somebody else for what's wrong with your computer. Note time limits on free phone support, and the per-incident costs thereafter; this means you had better have gotten the hang of the manufacturer's Web-based support--or have befriended or bribed some computer-savvy types--by the time those 90 days are up.