Emulex MD21/S2, Technical Manual

Page: 65 / 88

SCSI Bus Interface
Table 7-1. SCSI Bus Signals
Mnemonic
Name
Signal Description
DBO Data Bus Data Bus Bit 0
DB1 Data Bus Data Bus Bit 1
DB2
Data Bus Data Bus Bit 2
DB3 Data Bus Data Bus Bit 3
DB4 Data Bus Data Bus Bit 4
DB5 Data Bus Data Bus Bit 5
DB6
Data Bus
Data Bus Bit 6
DB7 Data Bus Data Bus Bit 7
DBP Data Bus Data Bus Parity
ACK Acknowledge
Indicates acknowledgment for a
REQ/ACK data transfer handshake
operation.
REQ Request
Indicates a request for a REQ/ACK
data transfer handshake
operation.
ATN Attention* Indicates ATTENTION condition
(i.e., the Initiator has a
message to send to the Target).
RST
Reset* Indicates RESET condition (i.e.r
clears the SCSI bus of all
activity).
SEL Select Used to select and/or reselect a
SCSI bus device.
BSY Busy
I
Indicates the SCSI bus is being
used.
C/D Control/Data Indicates command
,
status
information transfer# or data in
and/or data out transfer.
I/O Input/Output Indicates direction of data
movement on the data bus with
respect to an Initiator.
MSG
Message
Indicates the SCSI bus is in the
Message Phase.
*This condition is described in Section 5 of the Emulex SCSI Disk
Controller Programming Reference Manual (manual number MD2352501).
Interfaces 7-7