Information Transfer Phase Identification - Fujitsu MAN3184 SERIES Specifications

(2) BSY (BUSY)
The BSY signal indicates that the SCSI bus is in use. In the ARBITRATION phase, this signal is
used to request for the bus usage priority.
(3) SEL (SELECT)
The SEL signal is used by the INIT to select a TARG (in the SELECTION phase) or by the TARG
to reselect an INIT (in the RESELECTION phase).
(4) C/D (CONTROL/DATA)
This is a combination of I/O and MSG signals, and specifies a type of information transferred on
the data bus. The C/D signal is always driven by the TARG (see Table 1.1).
(5) I/O (INPUT/OUTPUT)
The I/O signal specifies the information transmission direction on the data bus. It is also used to
identify the SELECTION phase or RESELECTION phase. This signal is always driven by the
TARG (see Table 1.1).
(6) MSG (MESSAGE)
A signal sourced by a target to indicate the MESSAGE phase or a DT DATA phase depending on
whether C/D is true or false. Asserted indicates MESSAGE or DT DATA (see Table 1.1).
Table 1.1
Signal
C/D MSG I/O
0 0 0
0 0 1
0 1 0
0 1 1
1 0 0
1 0 1
1 1 0
1 1 1
1-6

INFORMATION TRANSFER phase identification

Phase
ST DATA OUT
ST DATA IN
DT DATA OUT
DT DATA IN
COMMAND
STATUS
MESSAGE OUT
MESSAGE IN
C141-E123-01EN
Direction
INIT -> TARG
ST Data phase
INIT <- TARG
INIT -> TARG
DT Data phase
INIT <- TARG
INIT -> TARG
INIT <- TARG
INIT -> TARG
MESSAGE
INIT <- TARG
Comment
Data phase