Sony SMO-F551 Technical Manual page 40

The following are the descriptions on the signals:
Busy (BSY)
An "OR-tied" signal that indicates whether the bus is being used.
Select (SEL)
A signal used either by the initiator to select the target or by the target to reselect an
initiator.
Control/Data (C/D)
A signal driven by the target to indicate whether CONTROL or DATA information is on
the DATA BUS. True indicates CONTROL.
Input/Output (I/O)
A signal driven by the target to control the direction of data flow on the DATA BUS with
respect to the initiator.
distinguishes phases between SELECTION and RESELECTION.
Message (MSG)
A signal driven by the target during the MESSAGE phase.
Request (REQ)
A signal driven by the target to indicate a request for REQ/ACK data transfer
handshake.
Acknowledge (ACK)
A signal driven by the initiator to indicate an acknowledgment for an REQ/ACK data
transfer handshake.
Attention (ATN)
A signal driven by the initiator to indicate the ATTENTION condition.
Reset (RST)
An "OR-tied" signal that indicates the RESET condition.
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SMO-F551 Technical Guide and Specifications
Sony Corporation 1998
True indicates input to the initiator. This signal also