User's Guide

SCSI Interface Description Page 23
SCSI Status Code Descriptions and Definitions
The status code format is shown in the following table. A status byte is sent from the
DAT drive to the Initiator during the Status phase at the termination of each
command unless the command is cleared by an Abort message, by a Bus Device
Reset message, or by a Reset condition.
BITS 7 6 5 4 3 2 1
Content 0 0 0 Status Code 0
The DAT drive uses the 4-bit status codes shown in the following table.
Bits
4 3 2 1 0 Definition
0 0 0 0 X Good Status
0 0 0 1 X Check Condition
0 1 0 0 X Busy
1 0 0 0 X Intermediate Status
1 1 0 0 X Reservation Conflict
Descriptions of the five supported SCSI status codes are given in the following table.
Message
Status
Code
Byte 0
Status
Phase
Definition
Busy 4h 08h This status (DAT drive busy) is returned when the drive is
unable to accept a command from the Initiator. (For example, it
is returned during an intermediate disconnect or after an
immediate command has completed and the request function is
not done.) The normal Initiator recovery action is to issue the
command at a later time.
Check
Condition
1h 02h Any error, exception, or abnormal condition that causes the
sense data to be set, causes a Check Condition status. A
REQUEST SENSE command should be issued following a
Check Condition status, to determine the nature of the condition.
Good
Status
0h 10h This status indicates that the DAT drive successfully completed
the command.
Intermedi
ate Status
8h 10h This status is returned for every command in a series of linked
commands except the last command unless an error, exception,
or abnormal condition causes either Check Condition or
Reservation Conflict status to be set. If this status is not
returned, the chain of linked commands is broken, and no
further commands in the series are executed.
Reser-
vation
Conflict
Ch 18h This status is returned when a device attempts to access a DAT
drive when it is reserved for access to another device.