; JED2EQN -- JEDEC file to Boolean Equations disassembler (Version V063)
; Copyright (c) National Semiconductor Corporation 1990-1993
; Disassembled from J070-U10.jed. Date: 2022-05-28
;$GALMODE REGISTERED

;
; Initial analysis: not tested yet!
;

chip J070-U10 GAL16V8
;
; microprocessor clock stretcher and synchroniser
;

CLK	=	1
/PTM	=	2	; Programmable Timer Module
/STE	=	3	; STEbus
AVM	=	4	; Advanced VMA signal
T1	=	5
RESP	=	6	; from U13 pin 4. == DATACK or TRFERR
BA	=	7	; from MPU
BS	=	8	; from MPU
/RST	=	9 	; Reset
GND	=	10
/OE	=	11	; permanently grounded!
/ENDR	=	12	; Enable Drive of STEbus buffers
E	=	13	; Constant frequency E to I/O devices for timing.
Q	=	14	; Constant frequency Q, I am guessing
EM	=	15	; E to MPU
QM	=	16	; Q to MPU
CS	=	17	; Active High. For UART and PTM
RESP_LATCHED	=	18	
/VMA	=	19	; actual VMA signal
VCC	=	20 



@ues 0000000000000000
@ptd unused

equations

VMA	=	AVM	*	/EM	*	/QM
	+	VMA	*	EM
	+	VMA	*	QM	*	/BA


/RESP_LATCHED	:=	/RESP


/CS	:=	/RST	*	PTM	*	/Q	*	/E	*	/QM	*	EM
	+	/RST	*	/CS	*	Q	*	/E
	+	/RST	*	/CS	*	Q	*	E
;
; I think the two lines above above could be reduced to 
;
;	+	/RST	*	/CS	*	Q

;
; E is a constant frequency to drive the UART and PTM chips.
; E becomes Q 
; Q becomes not E
;

/E	:=	/Q	*	E
	+	/Q	*	/E

/Q	:=	 Q	*	E
	+	/Q	*	E
;
; I think the two equations above could be reduced to 
;
;	/E	:=	/Q
;	/Q	:=	E
;
;
; QM and EM are the stretched clocks for the microprocessor.
;
;
/QM	:=	 QM	*	EM
	+	/QM	*	EM
;
; I think the equation above could be reduced to 
;
;	/QM	:=	 EM
;
; Things get tricky for clock stretching.
;
; EM becomes QM if no stretching, or stretching complete.
; It ends stretching when:
;	- not a valid memory cycle
;	- not STEbus and not PTM
;	- has STEbus timout
;	- the STEbus has responded (with DATACK or TRFERR)
;	- synchronising with the constant-frequency E and Q for I/O chip
;

/EM	:=	/QM	*	EM	*	/VMA
	+	/QM	*	EM	*	/STE	*	/PTM
	+	/QM	*	EM	*	T1
	+	/QM	*	EM	*	STE	*	/RESP_LATCHED
	+	/QM	*	/EM
	+	/QM	*	EM	*	PTM	*	/CS	*	/Q	*	E
;
; Enable STEbus buffers:
;
ENDR	=	/QM	*	EM	*	STE	*	/RST	*	VMA	*	/BA
	+	/QM	*	EM	*	STE	*	/RST	*	VMA	*	/BS

;
; All outputs are enabled, either by default or by OE tied active.
;
/VMA.oe	=	vcc
RESP_LATCHED.oe	=	OE
CS.oe	=	OE
QM.oe	=	OE
EM.oe	=	OE
Q.oe	=	OE
E.oe	=	OE
/ENDR.oe	=	vcc