Emerson MVME147 User Manual
A
COMMON COMMAND SET
AND DISK OPERATION
The first high level command required to interface with a Winchester disk is
an ATTACH. An ATTACH initializes the SCSI firmware pointers and internal
flags. A RAM work area is used to build the SCSI command descriptor block,
messages sent in the message-out phase, and a place to put incoming
messages, and status. This area also contains a copy of the ATTACH packet
parameters, and two work areas to for mode sense current values and
changeable values.
an ATTACH. An ATTACH initializes the SCSI firmware pointers and internal
flags. A RAM work area is used to build the SCSI command descriptor block,
messages sent in the message-out phase, and a place to put incoming
messages, and status. This area also contains a copy of the ATTACH packet
parameters, and two work areas to for mode sense current values and
changeable values.
The ATTACH command performs the following to a Winchester disk:
If bit 5 of attribute word is "1" (byte offset $10), The firmware sends a Reserve
Device SCSI Command ($16) to the SCSI device.
Device SCSI Command ($16) to the SCSI device.
Reserve Command CDB
NOTE:
Third party reservation not supported.
If the controller code (byte offset $12) is $17 (synchronous CCS), and if this is
the first ATTACH for this device, the firmware sends an identify message
followed by a synchronous data transfer request message and a test unit ready
command.
the first ATTACH for this device, the firmware sends an identify message
followed by a synchronous data transfer request message and a test unit ready
command.
Synchronous Data Transfer Request Message
BYTE OFFSET
VALUE
COMMENTS
0
16
Command code
1
00 (Note)
LUN is inserted into bits 7-5
2
00
Reserved
3
00
Reserved
4
00
Reserved
5
00
Control byte: no link, no flag
BYTE
VALUE
COMMENTS
0
C0
Identify with reselection
message
message