Viper 60s Theory Of Operation And Maintenance Manual page 98

VI/PER SCSI 60,
125
& 150 THEORY OF OPERATION AND MAINTENANCE
5.16.7 Parameter List-Block Descriptor Field Descriptions Continued
NAME
I
BYTES
DESCRIPTION
Explicit Mode
Number of
Blocks
Block
Length
The Viper drive enters the explicit mode by:
1. Reading a tape
2. Writing a tape
3. With density code field set to non-zero in the Mode Select
command. If the drive is operating in the QIC-11, QIC-24,
QIC-120, or QIC-1S0 format, the drive is in the explicit
format mode.
READ In Read Operation, the drive only recognizes the selected
Explicit Mode. READ commands on all other formats are
terminated with a Check Condition and a Sense Key of Blank
Check.
WRITE In Write Operation, the drive only writes in the selected Explicit
Mode. If the installed cartridge does not support the selected
Explicit Mode, the Write command terminates with a Check
Condition and a Write Protect.
1 -3
5-7
If the Selected Density Mode is an 04h or OSh in a 12SS or
lS0S, the write operation terminates with OSh Illegal Request.
If Mode Select is issued to change the Density Code, the
change is not reported in Mode Sense until a write or read
operation is completed.
This field is set to all zeros indicating that all logical blocks
have the format specified in the Density Code field.
This field is set to OOh, 02h, OOh indicating a fixed-block length
of 512 bytes.
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