; JED2EQN -- JEDEC file to Boolean Equations disassembler (Version V063)
; Copyright (c) National Semiconductor Corporation 1990-1993
; Disassembled from SPEC_Y.JED. Date: Date: 2025-09-17

chip SPEC_Y PAL14L4

; RAM_CE = 1	; ignored?
/KEYIO	= 2
A15	= 3
A14	= 4
A13	= 5
A12	= 6
A11	= 7
A10	= 8
A9	= 9
GND	= 10
A8	= 11
A7	= 12
A0	= 13
;
;
;
/RA0	= 14
/RA1	= 15
/RA2	= 16
/RA3	= 17

; NC18	= 18
; NC19	= 19
VCC	= 20


equations

RA3	= KEYIO
	+ A0 * /A7
;
; RA2 is low 
;
RA2	= KEYIO * A15 * A14 * A13 * A12 * /A11				; 0b11110xxx
	+ KEYIO * A15 * A14 * A13 * A12 *  A11 * /A10			; 0b111110xx
	+ KEYIO * A15 * A14 * A13 * A12 *  A11 *  A10 * /A9		; 0b1111110x
	+ KEYIO * A15 * A14 * A13 * A12 *  A11 *  A10 *  A9 * /A8	; 0b11111110

; The Spectrum keyboard keys in Spectrum I/O space look like this:

; AAAAAAAA	
; 111111	d d d d  d
; 54321098	4 3 2 1  0
;
; 01111111	B N M sh space
; 10111111	H J K L  enter
; 11011111	V C X Z  caps
; 11101111	Y U I O  P
; 11110111	6 7 8 9  0
; 11111011	G F D S  A
; 11111101	T R E W  Q
; 11111110	5 4 3 2  1

; It is read at port FE (A7-0)
; but IN A,(C) actually works like IN A,(BC) with register B driving A15-8.
;
; I'm puzzled because the logic looks like RA2 is active for only 4 out of 8 rows.
;


; unused

RA1	= vcc

RA0	= vcc