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Interface Information
7957A/7958A
BIT
POSITION
15
14
13
12
11
10
9
8
7
6
5
4
2-4
Table 2-3. Standard Status Response Bits
(l
of 2)
DESCRIPTION
Reserved. This bit is always zero.
Removable Media Not Present. The drive does not use removable media,
therefore this bit is always zero.
Write Protected, Removable Media. The drive does not use removable media,
therefore this bit is always zero.
Write Protected, Fixed Media. The drive does not include a write protect fea-
ture, therefore this bit is always zero.
Reserved. This bit is always zero.
Reserved. This bit is always zero.
Spindle Motor Stopped. This bit indicates the spindle motor is not up to speed.
If this bit is set, the controller should send a Control command specifying a
Start Spindle Motor operation. A change of state on this bit due to the suc-
cessful execution of a Start Spindle Motor or Stop Spindle Motor operation
does not cause ATTENTION to go active.
Power-On Reset Conditions Exist. This bit notifies the controller that the
drive operating parameters have been set to their default values. This bit is set
following a power-on sequence or when an internal drive fault condition oc-
curs that causes an internal power-on reset operation to occur (e.g., a momen-
tary loss of dc power). The controller may have to reconfigure drive operat-
ing conditions. The controller should also check the Spindle Motor Stopped
status bit (bit 9) and perform a motor-on sequence if necessary.
Command Data Parity Fault. This bit indicates that the drive detected a
parity error on the serial command data received from the controller. The
drive will not attempt execution of the command if a parity error is detected.
Interface Fault. This bit indicates that the drive has detected an interface
protocol timeout. An Interface Fault occurs when the controller fails to
respond to an edge of the TRANSFER REQ/TRANSFER ACK handshake
protocol within 13 milliseconds (see figure 2-5).
Invalid Or Unimplemented Command. This bit indicates that the drive has
received an invalid or reserved command, command modifier, or command
parameter. The drive will also set this bit if the controller sends a valid com-
mand that the drive is currently unable to execute (e.g., a Seek command while
the spindle motor is stopped).
Seek Fault. This bit indicates that a catastrophic seek failure occurred. This
bit will be set only after the drive has made every attempt to successfully
complete the seek. The controller may elect to retry the seek operation,
however such retries will most likely be unsuccessful.
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