Specifications

Parallel-port scanners have some significant disadvantages, though. First, juggling any combination of
devices beyond a scanner and a printer can be difficult. With Zip, LS-120, CD-R/CD-RW, tape backup,
and other types of removable-media drives often fighting for the parallel port, the order in which
devices are connected to the computer can be critical. Should the Zip drive or the scanner be con-
nected first? The printer must be the last item in the daisy-chain because printers lack the pass-
through ports used by the other devices. You’ll need to experiment or add a second LPT port to
separate your scanner and printer from other devices.
A second disadvantage is scanning speed. Even if your scanner can use the fastest ECP or ECP/EPP
port modes, the parallel port can’t lay a glove on the faster SCSI, USB, or IEEE-1394 ports.
A third disadvantage is operating-system compatibility. Most parallel-port scanners won’t work with
Windows NT4.0, for example, and cannot be used with most Macs or so-called legacy-free PCs (which
use USB ports in place of serial, parallel, keyboard, and mouse ports). Use parallel-port scanners for
light-duty operation with consumer versions of Windows (9x/Me) or when other types of expansion
aren’t feasible.
SCSI Interfacing
As you saw in Chapter 8, “The SCSI Interface,” SCSI interfacing is extremely flexible, providing for
daisy-chains of up to seven SCSI devices of varying types and even more with advanced SCSI interface
cards. The SCSI Interface is covered in more detail in Chapter 8.
In tests, a typical scanner equipped with both SCSI and USB ports scanned an 8”×10” color image in
about half the time using the SCSI port as compared to when the USB port was used. SCSI is the best
choice for users who need speed and flexibility and who already have a SCSI interface or don’t mind
the extra cost of the card (some scanners come with an appropriate interface card).
Note that some vendors are now switching to USB ports in place of SCSI for some models because
both offer daisy-chaining, but SCSI remains the better choice for high performance.
If your SCSI-based scanner comes with a host adapter card, can you use it for other devices?
Frequently, the answer is “Probably not.” Such low-cost cards are often optimized just for scanner sup-
port. I have used some cheap SCSI cards of this type to attach to a scanner and SCSI Zip drive, but
more elaborate daisy-chains aren’t recommended and often don’t work.
USB Interfacing
The Universal Serial Bus is the latest widely available port and is beginning to replace serial and paral-
lel ports. For users needing to mix the “no-brainer” installation typical of parallel-port devices with
the flexibility of SCSI device handling, USB is the way to go for hobbyist use on systems featuring
with Windows 98, Windows Me, or Windows 2000. USB is covered in more detail in Chapter 17,
“Serial, Parallel, and Other I/O Devices.”
Note
Not every USB device is supported by Windows 2000. Before you buy a USB scanner for use with Windows 2000,
verify that you have Windows 2000 drivers available for it.
IEEE-1394 (i.Link/FireWire) Interfacing
Recent developments in scanner technology have made the development of 1,000dpi and above opti-
cal scanners at reasonable prices possible. Scanners with this level of performance can be used to cre-
ate incredibly sharp and detailed scans, but only by delivering an enormous amount of data to the