The last step before buying a scanner is to try to gauge how difficult it will be to install the models under consideration. If you're an experienced user confident in your ability to install add-in cards, configure system software, and set up drivers, then ease-of-installation probably won't count for much. If you're a beginner, though, here are some important points to consider:

Not every computer can run every scanner. Before buying a scanner, check to make sure that your system meets all of the requirements listed by the scanner manufacturer. Generally, a modern scanner requires a Windows PC with at least a 486/33 processor, or a Macintosh with a 68030 processor. The amount of RAM installed is also important, because scanning and editing graphics is memory-intensive. Plan on having at least 12Mb installed, and double that for true ease-of-use.

One physical limitation imposed by most scanners is the length of the cable between the scanner and the computer. Although longer cables can be substituted in some situations, scanners that rely on SCSI connections (see below) typically must be positioned within twelve feet of the computer. If that's a problem, consider re-orienting your system or look around for a different type of scanner.

Every scanner needs to be connected to a computer, so at the very least every scanner should come with a cable for accomplishing that task. Beyond that, if the scanner requires a connection that's not common to most computers, it should come with an add-in card or other device for establishing that connection.

Many handheld and sheetfed scanners don't require an add-in card because they connect to the parallel port that's found on the back of most computers. Among flatbed, slide, and some sheetfed scanners, however, it's common to use a special type of connection called SCSI.

All Macintosh systems come with built-in SCSI support, but only a few Windows PCs include that feature. In most cases, these PCs require an add-in SCSI board that fits in one of the computer's expansion slots and provides a SCSI port for the scanner to plug in to. These add-in cards are available from Adaptec and other manufacturers, and are available for a variety of PCs. With a SCSI card installed, most PCs can be connected to several SCSI devices as long as they are all linked together in a chain.

For convenience, many manufacturers supply their scanners with a low-end SCSI card that will support only their scanner. While not as powerful as general-purpose SCSI cards, these models usually get the job done. One thing to look out for is how recent the card is; an older, 8-bit card can't process data as quickly as a newer, 16-bit card. Older cards may also have small switches that need to be set before the card can be installed, and they may conflict with existing devices already installed in your computer. For the greatest ease of installation, look for a scanner with a switchless, 16-bit card, preferably from a well-known manufacturer.

Though they may seem a bit mundane, the instructions that come with a scanner can be tremendously important to the correct installation and use of that model. Before buying a scanner, check to make sure that all of the instructions are clear and easy to follow. Because most scanners are manufactured overseas, this isn't always the case.

Also, be on the lookout for accessories that ease the installation process. Some manufacturers include a videotape explaining the installation process, while others bundle in books that explain color scanning in greater detail. These items not only make using a scanner less taxing, but also signal that the manufacturer in question cares about its customers.