Select (SEL)
With the tape unit in Ready Status and Online Status, asserting the Select input command line allows all control and motion command input lines to be effective for the tape unit. All motion status output lines are valid only when Select is asserted.
Select may be asserted before or after the assertion of a motion command line but tape unit operation will begin upon the assertion of the later command.
Select must remain asserted for the duration of a Set Forward Motion or Set Backward Motion command. If Select is reset before Set Forward Motion or Set Backward Motion, the operation will terminate. In this mode of operation Select acts as a start/stop line.
Select must remain asserted for a Set Rewind or Set Rewind/Unload command only until the command has been accepted, which is signaled when the tape unit resets the Ready Status output line.
Set Forward Motion (FWD)
When the Set Forward Motion input command line is asserted, it commands the tape unit to move tape forward at nominal speed. This line must remain asserted for the duration of the desired command operation length. The line is effective only if Select, Online Status, and Ready Status are asserted, and is ineffective if any other command operation (Set Backward Motion, Set Rewind, Set Rewind / Unload) is in progress.
Set Backward Motion (BWD)
When the Set Backward Motion input command line is asserted, it commands the tape unit to move tape backward at nominal speed. This line must remain asserted for the duration of the desired command operation length. The line is effective only if Select, Online Status, and Ready Status are asserted, and is ineffective if any other command operation (Set Forward Motion, Set Rewind, Set Rewind / Unload) is in progress.
A backward motion command operation automatically resets Write Status and Erase Status in the tape unit. The Set Write Status input control line is ineffective during a backward motion command operation.
Set Rewind (RWD)
When the Set Rewind input command line is asserted, it commands the tape unit to reset Ready Status and to rewind tape. When BOT is detected, the tape stops and Ready Status is set again. The line is effective only if Select, Online Status, and Ready Status are asserted and if tape is not already positioned at BOT. The line is ineffective if any other command operation (Set Forward Motion, Set Backward Motion, Set Rewind / Unload) is in progress.
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9360
Set Rewind should remain asserted until the command has been accepted by the tape unit, which is signaled when the tape unit resets Ready Status.
Alternately, a pulse duration of 10 microseconds of Set Rewind and Select simultaneously is sufficient to ensure setting a rewind command.
A rewind command operation automatically resets Write Status and Erase Status and sets Backward Status in the tape unit.
Set Rewind/Unload (RWU)
When the Set Rewind I Unload input command line is asserted, it commands the tape unit to reset Ready Status, rewind tape to BOT, stop tape motion momentarily at BOT, and then unload all tape onto the file reel. The line is effective only if Select, Online Status, and Ready Status are asserted, and is ineffective if any other command operation (Set Forward Motion, Set Backward Motion, Set Rewind) is in progress.
Set Rewind I Unload should remain asserted until the command has been accepted by the tape unit, which is signaled when the tape unit resets Ready Status. Alternately, a pulse duration of 10 microseconds of Set Rewind/Unload and Select simultaneously is sufficient to ensure setting a rewind / unload command.
A rewind I unload command operation automatically resets Write Status and Erase Status and sets Backward Status in the tape unit.
The function of this line can be changed to Set Offline by a movable jumper. In this mode, the drive is placed offline but tape is not unloaded.
Set High Density (HDN)
To set the tape unit to PE mode for a Virite operation, the Set High Density input control line must be asserted when the Set Forward Motion input command is issued at BOT. Set High Density should remain valid during command initiation until the tape unit responds with the corresponding state of High Density Status.
Alternately, a pulse duration of 10 microseconds following the assertion of Set Forward Motion is sufficient to ensure setting High Density Status. If this line is unasserted when the Set Forward command is issued at BOT, the tape unit will be set to NRZI mode.
To set the tape unit to PE for a read operation, the Set High Density line is asserted when either a Set Forward Motion or Set Backward Motion command is reset following an operation. For this to occur, Select must remain asserted past the reset of the motion command. If Set High Density is unasserted under these conditions, the tape unit will be set to NRZI mode.
EC 44329 3-21
KIT PN 98362-7
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Set Write Status (WRT)
To set the tape unit to Write Enable, the Set Write Status input control line must be asserted when the Set Forward Motion command is issued. Write Enable is reset by issuing Set Forward Motion with Set Write Status unasserted (Set Read Forward mode) or by issuing Set Backward Motion (Set Read Backward mode).
This line is effective only if the tape unit File Protect Status output line is not
asserted.
-Set Write Status should remain asserted during command initiation until the tape unit responds with the corresponding state of Write Status. Alternately, a pulse duration of 10 microseconds of Set Write Status (with Set Forward Motion and Select asserted) is sufficient to ensure setting Write Enable.
The Write Status output line must be unasserted when a read-only command is to be initiated.
LRC Strobe (LRC)
The LRC Strobe input line is used with NRZI format write data to reset the internal tape unit data registers following the last character in the data block. It resets the polarity on tape to the IBG erase direction for all nine tracks.
Low Threshold (L TH)
The Low Threshold input line controls the threshold of detection when converting analog read data signal to a digital signal. Low Threshold is asserted during a read operation to recover drop out signal levels.
Write Data Strobe (WOS)
The Write Data Strobe input line is used to gate write data into the tape unit. The Write Data Strobe must have a duration of 1.0 microsecond minimum.
Write Data (WOP-W07)
The nine Write Data input lines carry the data from the controller to the tape unit. When writing PE characters the tape unit must be in high density mode;
when writing NRZI characters the tape unit must be in low density mode. PE mode Write Data must be valid a minimum of 0.5 microseconds before the assertion of the Write Data Strobe; NRZI mode Write Data must be valid a minimum of 1.5 microseconds before the assertion of the Write Data Strobe.