This article is from the Apple II Csa2 FAQ, by Jeff Hurlburt with numerous contributions by others.
The main Zip installation step is plugging it in. The drive uses DB-25 connectors and, so, most likely, the cable will plug directly into your interface card with no need for an adaptor. In case you need an adaptor for an older 50-pin plug, these can be obtained from Alltech. If you already have other SCSI devices, the one currently plugged into the interface can plug into the Zip. Or, the Zip can be plugged into a hard disk, CD-ROM, etc. at any point in the chain of SCSI devices. Set SCSI ID Number- Every hard disk, CD-ROM drive, etc. on your SCSI chain needs its own ID number (0-7). While most devices are flexible and will allow you to choose any available ID, Zip gives you a choice of two: 5 or 6. If you are using an Apple Hi-Speed card and you already have a hard disk, you'll have to set the Zip to 5 in order to continue to boot off of your hard disk (which needs to be 6). The RamFAST is somewhat more flexible in that it doesn't take ID 7 for itself and will allow you to boot f rom any SCSI device. Set Termination- Another consideration is termination. If all you have connected to your SCSI card is the Zip Drive, then you should set the switch on the back to turn ON the termination. If you have other devices that come after the Zip, then you should set it to OFF. (Actually, the Zip presents a light termination load and can be left with termination ON whether or not it is the last device.) The last device in the chain (the one farthest from the interface) should always have termination set ON. Hardware-wise, that's it. In all likelihood, your setup will work fine. If not, you can get help from experts at Alltech, post a question on comp.sys.apple2, or, even, read the documentation that came with your SCSI card (when all else fails ...). ----------------------------