hard disk (disk): a round magnetized plate, usually made of plastic or metal,
organized into concentric tracks and preshaped sectors for storing data.
(Usually faster than a diskette (floppy disk), holding 20 megabytes of data or
more, but also more expensive.)
floppy disk (diskette): a flexible platter covered with magnetic recording
material that permanently stores programs and data. Floppy disks come in
two basic sizes: 5 1/4-inch and 3 1/2-inch and hold 360K to 1.4 megabytes of
information. Most users need at least 1 to 2 floppy disks or a hard drive.
Figure 2-14. The magnetic disk is a metal platter coated on both sides with
magnetizable material. Data are stored on concentric tracks.
minicomputer: a mid-sized computer, with all the components of a full-sized
computer but a smaller capability. (This term is falling into disuse as the
distinction between large and 'super-mini' computers blurs.)
(c) Key-to-diskette systems. This increasingly popular configuration
makes use of a flexible (or floppy) diskette instead of the conventional (hard) disk. The
data is entered on a keyboard, displayed on a screen for the operator to check, and
recorded on the diskette. Systems that use disks or floppy disks have a disk drive.
Moving heads inside the disk drive can "read" the magnetically stored information on a
disk's surface and transfer the contents to the machine's internal memory. The heads
can also magnetically "write" information on the disk as required.