First some background on SCSI adapters. SCSI is a rather useful Bus system, similar to IDE. It is used on all MacIntosh computers and Unix work stations, and in some PC computers.
SCSI adapters can handle up to 7 devices each. Typical devices include CD ROM drives, scanners, tape drives,disk drives, magneto-optical drives, CD ROM recorders, WORM drives, and tape and CD ROM changer devices.
Zip drives are available in two types, parallel port and SCSI. Your PC is capable of using both types (with appropriate adapters, in the case of the SCSI). The parallel port version is mainly limited to PC computers and it has rather poor performance compared to the SCSI version.
If you are planning to use the SCSI version, you should consider whether you have a SCSI interface or need to get one. SCSI adapters bridge a SCSI bus with the data bus of your computer. Information regarding data buses
PCI 32bit- It is the smallest in size but the fastest because it is the most recent. Your PC must be a very recent one to have this type (i.e. a Pentium or PowerMac).
PCMCIA or PC Card 32bit- Laptop/notebook computers have these. Credit card size components go into these.
VESA 32bit- Found in 486 computers, usually 2 or 3 of these and the video card is plugged into one of these. These are faster than ISA and are an extension to the ISA bus.
ISA 8/16bit- All PCs except notebooks have these, usually from 4 to 7.
If you plan on adding other SCSI devices to your computer in the future, I suggest using a 32bit-SCSI adapter(either VESA or PCI). If the Zip drive is the only SCSI device you expect to use on your computer, get an ISA-> SCSI adapter as they are cheaper and plenty fast for using a Zip drive. The Zip Zoom is in this last category (ISA to SCSI)>