IBM System/370 Operator's Reference Manual page 184

IBM 3340 Disk Drive
Source: GA26-7619 IBM 3340 Reference Manual
READ ONLY FUNCTION
The means
to
protect previously written data modules is provided by the Read Only
function. The following procedures show how to enable or disabJe the Read Only
function for either 3348 model.
Enable Read Only Function
1. With data module removed from the drive, press down on IBM logo inset of
the handle
(A).
2.
Turn inset 100
0
and snap into place (B).
3.
The data module may
now
be loaded in the desired drive.
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