Fujitsu 600C manual 2Bus signals

4.2.2Bus signals

Table 4-2Bus signals

Signal name

Type of signal

Initiator

⇐

⇒

Target

Data	DB0	Eight data-bit signals, plus a parity-bit signal that forms a DATA
	DB1	BUS. DB(7) is the most significant bit and has the highest
	DB2	priority during the ARBITRATION phase. Bit number,
	DB3	significance and priority decease downward to DB(O). A data bit
		is defined as one when the signal value is true. A data bit is
	DB4
		defined as zero when the signal value is false. Data parity DB(P)
	DB5
		shall be odd. Parity is undefined during the ARBITRATION
	DB6	phase.	⇐
	DB7		⇒
	(Data Bus n)
	DBP
	(Data Bus Parity)
Control Signals	BSY (Busy)	An "ORtied" signal that indicates that the bus is being used	⇐
			⇒
	SEL (Select)	An "ORtied" signal used either by an initiator to select a target or	⇐
		by a target to reselect an initiator	⇒
	RST (reset)	An "ORtied" signal that indicates the RESET condition	⇐
			⇒
	C/D (Control/Data)	The C/D, I/O, and MSG signals are used to distinguish between	⇐
	I/O (Input/Output)	the different information transfer phases.
	MSG Message
	REQ (request)	A signal driven by an initiator to indicate a request for a	⇐
		REQ/ACK data transfer handshake
	ACK (acknowledge)	A signal driven by an initiator in indicate and acknowledgment	⇒
		for REQ/ACK data transfer handshake.
	ATN (Attention)	A signal driven by an initiator to indicate the ATTENTION	⇒
		condition

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