The better ones are digital but their cost is excessive for the personal user. The cost is reasonable, but recovering selected data can take a long time. In addition, I have experienced frequent difficulties reading the tape when I needed it most. Iomega Corporation makes an external drive, called the ZIP drive, which uses 100 Meg diskettes. It connects to the printer port.
Internal units are also available.
Iomega also makes a JAZ drive which is essentially a hard drive with removable cartridges. In most applications, it installs inside the computer, but is also available as an external unit. Speedwise the JAZ is about 7 times faster, stores 10 times more, but costs about 4 times as much. I recommend it for small businesses. I have both types of drives here and found them to be extremely reliable.