Intel mcs-48 manual Modified State Diagrams, Figure A.1 State Diagrams next

8291

Appendix A

MODIFIED STATE DIAGRAMS

Figure A.1 presents the interface function state diagrams. It is derived from IEEE Std. state diagrams, with the following changes:

A. The 8291 supports the complete set of IEEE-488 interface functions except for the controller. These include: SH1, AH1, T5, TE5, L3, LE3, SR1, RL 1, PP1, OC1, OT1, and co.

B. Addressing modes included in T,L state diagrams.

Note that in Mode 3, MSA, OSA are generated only after secondary address validity check by the microprocessor (APT interrupt).

C.In these modified state diagrams, the IEEE-488 con· vention of low true logic is followed. Thus, OAV is log·

ically true at <O.8V and is equivalent to pin 36 on the 8291.

O. All remote multiline messages decoded are condi· tioned by ACOS. The multiplication by ACOS is not drawn to simplify the diagrams.

E. The symbol x--8

indicates:

1.When event X occurs, the function will return to state S.

2.X overrides any other transition condition in the function.

Statement 2 simplifies the diagram, avoiding the explicit use of Xto condition all transitions from S to other states.

r ---- l

I	I
I SH	I
I	I

L ____ ..J

pon

ATN+ i=1

(WITHIN t2) DAV

F1 '"TACS + SPAS

r ------ ,

I	I
I AH	I
I	I
L ___ _ J

		*THIS TRANSITION WILL NEVER
		OCCUR UNDER NORMAL OPERATION.
pon----	l~	tTOELAY IS ABOUT 300 NS
		FOR DEBOUNCING DAV.

F3~ATN+rdy	F3 + T3'·ATN	. DAV
T3''"T3 • CPT· APT

BI

NRFD

Figure A.1. 8291 State Diagrams (Continued next page)

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