DEC VAX 4000 300 Manual page 61

Your system can read information on the tape regardless of the position of
the write-protect switch or whether writing is software disabled. However,
the system cannot write data to the tape when the write-protect switch is
set to the write-protect position, or when writing is software disabled.
When you use a cartridge to install software, make sure the cartridge is
write protected. Two icons on the switch indicate the write-protect status,
as shown in Figure 3–5. An orange rectangle is visible when the switch is
in the write-protect position. If you do not see an orange rectangle, slide
the switch toward the label slot.
When you insert a write-protected cartridge into the drive, the orange write-
protect indicator lights. The system recognizes the tape as being write-
protected under any one of the following conditions:
• The write-protect switch on the cartridge is set to the write-protect
position.
• An operating system command has write-protected the tape.
• A tape recorded on a TK-series tape drive is inserted into the drive.
Removing write-protection depends on how the tape was recorded and how
it is write protected. You cannot write-enable a tape recorded on a TK50
/TK70 tape drive either by moving the write-protect switch on the cartridge
or by using software commands. The TF85 tape drive always recognizes a
tape recorded on a TK50/TK70 drive as write-protected. You can remove
write-protection on tapes recorded on a TF85 tape drive as follows:
• If the cartridge is write protected only by the write-protect switch on the
cartridge and not the operating system, moving the switch to the write-
enabled position causes the write-protect indicator light to go out.
3–10 VAX 4000 Model 300 Operation