IBM 5150 Manual To Operations page 93

About Diskettes
Your IBM Personal Computer uses 5-1/4 inch (133 mm)
diskettes for storing information. (You may also have
heard the terms "floppy diskette," "mini-floppy," or
"disk"-we will use "diskette.")
These diskettes can hold about 160,000 characters
(would you believe 163,840!) of data and/or program
information. That's about 110 pages from a book.
Write Protect Notch
(Some diskettes do
not have this notch.)
Exposed Recording
Surface
(DO NOT TOUCH)
Protective
Head Slot
Jacket
....---Ir--Diskette
Envelope
The permanent protective jacket (which is black)
contains a flexible diskette that is coated with a
magnetic substance. When in use, the diskette spins
inside the jacket. The read/write head comes into
contact with the recording surface through the long
hole in the protective jacket, called the head slot.
Information is written to or read from the magnetic
surface of the diskette, similar to the wayan
ordinary tape recorder operates.
The information on a diskette can be read by the
computer as often as it needs, or the computer can
write new information on the diskette in an unused
space.
Or the computer may replace old information with new
information by writing over it. In this case, the old
information is erased and can no longer be read.
Similarly, if you record a Chicago Symphony program
on an Elvis Presley tape, you can no longer listen to
Elvis.
DOS 3-19