Intel mcs-48 manual Mode 3 PIN Description

8293

Symbol	I/O	Pin No.	Function
	I/O	3	End or Identify;	processor
			GPIB bus control line; used by
			a talker to indicate the end of
			a multiple byte transfer se·
			quence. This pin is TTL com·
			patible.
EOI'	I/O	15	End or Identify; IEEE GPIB bus
			control line; used by a talker
			to indicate the end of a multi·
			pie byte transfer sequence or,
			by a controller in conjunction
			with ATN, to execute a polling
			sequence. Whel1	an output,

this pin can sink 48 mA cur· rent. When an input, it is a TTL compatible Schmitt·trigger.

MOoE3

OPTA

OPTB

MODE 3 PIN DESCRIPTION

Symbol	I/O Pin No.			Function
T/R1		Transmit		receive	1; controls
		the direction for DAV and the
		010 lines. If T/R1 is high, then
		all these lines are sending
		information to the IEEE GPIB
		lines. This input is TTL com·
		patible.
EOI	3	End	of Sequence and			Atten·
ATN	4	tion;	processor GPIB			control
		lines. These two control lines
		are ANDed together to deter·
		mine whether all the tran·
		sceivers in the 8293 are push·
		pull	or open·collector. When
		both signals are low (true),
		then the controller is perform-
		ing a paiallei poli and the
		transceivers are all open-
		collector.		These	inputs are
		TTL compatible.

23Attention Out; processor GPIB control line; used by the 8292 during "take control syn- chronously" operations. This pin is TTL compatible.

oAV I -- Y> - 4 - + - I

T/l!1 1--i>O-+-{>O~...J

DID, 1 -----	+ - 1
010,1 -----	+ - 1
010, 1 -----	+ - 1
010, 1 -----	+ - 1
010,1 -----	+1
010 . 1 -----	+ - 1
010,1 -----	+1

2

I/O 24

DAV' I/O 21

I/O 25,23, 10,9, 8,7,

6, 5

Interface Clean Latched; used to make DAV received after the system controller asserts IFC. This input is TTL compatible.

Data Valid; processor GPIB handshake control line; used to indicate the condition (availability and validity) of in- formation on the 010 signals. This pin is TTL compatible.

Data Valid; IEEE GPIB hand- shake control line. When an input, this pin is a TTL com- patible Schmitt-trigger. When DAV'is an output, it can sink 48 mA.

Data Input/Output; processor GPIB bus data lines; used to carry message and data bytes in a bit-parallel byte-serial form controlled by the three handshake signals. These lines are TTL compatible.

ATN

Figure 6. Talker/Listener/Controller Data Configuration

0101'- I/O 22,19, Data Input/Output; IEEE GPIB

0108' 18,17, bus data lines. They are TTL 16,15, compatible Schmitt-triggers 13,12 when used for input and can sink 48 mA when used for out-

put.

9-114