IBM 3270 Hardware User's Manual page 90

Writing on Diskettes
You cannot write onto diskettes that don't have
a notch in the side.
(j
•
Write-Protected
You can write onto diskettes that have a notch.
(j
I
Non-Write-Protected
You can protect a diskette with a notch by
placing a tab over the notch. Tabs are usually
included in boxes of diskettes.
Formatting Diskettes
New diskettes must be formatted before you can
write onto them. See the FORMAT command in
the
Disk Operating System manual, for
instructions on formatting blank diskettes.
Chapter 3. Operating Your 3270 Personal Computer 3-7