A typical hard disk is built right into your computer or is housed in a box nearby-and you never see the actual hard disk or take it out of its container. A cartridge hard disk, though, is removable. It works kind of like a giant floppy disk in that it slips into a slot in a special kind of removable hard drive case (actually, it's more like sliding a video tape into a VCR). A typical cartridge hard disk holds 44 megabytes (there are also 88s), costs as little as $40, and is about as big as a cheese sandwich with no lettuce. The drive (the case) that you put the cartridge into costs from $450 to $1000.But once you have the hard drive, buying a new cartridge is the cheapest way to increase the amount of hard disk space you have.
Some people feel cartridges are not as dependable for storing data, but others swear by them. I am one of those who swear. I have about 8 cartridges, each 44 megs. I can store backups of all my books on one cartridge and put it in a safety vault. I can keep System 6 on a cartridge so when necessary I can just switch back to 6. I keep all my teaching materials on a cartridge so when I trot off to the college I just bring the cartridge with me, pop it into the removable drive in the classroom, and use my own System and fonts and files. I do the same for the various presentations and workshops I speak at. Oh, I do think cartridges hard disks are a marvelous invention.