CX85 Keypad Interrrupt Handler#
original Atari source from the CX-85 Disk
;DEMONSTRATION OF CX-85 KEYPAD INTERRUPT HANDLER
;FLORA P. NG 3/08/82
;
;This keypad interrupt handler detects and handles all
;keys pressed on a CX-85 keypad plugged into port 2.
;This is assembled using Atari Macro Assembler.
;
TIMER EQU $30
TIMER1 EQU 6
START EQU $9 ;START MASK
SELECT EQU $A ;SELECT MASK
OPTION EQU $C ;OPTION MASK
BPOT EQU $08 ;BPOT BIT MASK
VVBLKD EQU $224 ;VERTICAL BLANK INTERRUPT
STRIG1 EQU $285 ;TRIGGER 1
ATTRACT EQU $4D ;ATTRACT MODE FLAG
CH EQU $2FC ;KEYBOARD CODE
ALLPOT EQU $D208 ;ALL POT STATUS
PORTA EQU $D300 ;PORTA
SETVBV EQU $E45C ;ROUTINE FOR SETTING VECTORS
DOSINI EQU $0C ;WARM START ADDR
CONSOL EQU $D01F ;CONSOL SWITCH PORT
BREAK EQU $11 ;BREAK KEY FLAG
;LOCATED IN PAGE 6 BUT MAY BE REASSEMBLED ELSEWHERE
;
;INITIAL ENTRY POINT TO ESTABLISH VBLANK ENTRY
;SYSTEM RESET KEY RESETS VBLANK VECTORS,
;HENCE CHAIN TO DOS INIT
;SAVE VALUE IN DOSINI
ORG $600
COLDST: LDA DOSINI
STA WRMEXT+1
LDA DOSINI+1
STA WRMEXT+2
;REPLACE DOSINI WITH WARMST
LDA #LOW WARMST
STA DOSINI
LDA #HIGH WARMST
STA DOSINI+1
;CHAIN KEYPAD INTO DEFERRED VBLANK PROCESSING
;SAVE VVBLKD FOR KEYPAD EXIT POINT
KPADVBI: LDA VVBLKD
STA EXIT+1
LDA VVBLKD+1
STA EXIT+2
;
;REPLACE VVBLKD WITH KEYPAD ENTRY POINT
LDY #LOW KPAD
LDX #HIGH KPAD
LDA #7 ;DEFERRED VBI
JSR SETVBV
RTS
;
;ENTERED WHEN USER HITS SYSTEM RESET
;REESTABLISH VBLANK VECTOR
WARMST: JSR KPADVBI
WRMEXT: JMP 0 ;CHAIN TO DOSINI
;
;
;KEYPAD TRANSLATION TABLE
;
KPADTAB: DB $0C,$0C ;FUNCTION 1
DB $14,$34 ;FUNCTION 2
DB $10,$07 ;FUNCTION 3
DB $18,$26 ;FUNCTION 4
DB $1C,$32 ;0
DB $19,$1F ;1
DB $1A,$1E ;2
DB $1B,$1A ;3
DB $11,$18 ;4
DB $12,$1D ;5
DB $13,$1B ;6
DB $15,$33 ;7
DB $16,$35 ;8
DB $17,$30 ;9
DB $1D,$22 ;.
DB $1F,$0E ;-
DB $1E,$06 ;+ENTER
DB 0 ;END OF TABLE
;ENTERED AT EACH VBLANK TO READ THE KEYPAD
KPAD: LDA STRIG1 ;KEY PRESSED?
BNE KPADDM ;EXIT FOR KEY NOT PRESSED
LDA #0 ;RESET ATTRACT
MODE
STA ATTRACT
;DETERMINE VALUE OF KEY PRESSED
LDA PORTA ;READ CABLE PIN OF PORT 2
LSR A
LSR A
LSR A
LSR A
STA TEMP
LDA ALLPOT ;READ ALLPOT FOR 5TH CABLE PIN STATUS
AND #BPOT ;MASK FOR 5TH PIN
EOR #BPOT ;COMPLEMENT BIT (O IS VALID)
ASL A
ORA TEMP ;A HAS KEY VALUE
LDY #0 ;INIT COUNTER
;
;SCAN TRANSLATION TABLE
KPADCK: CMP KPADTAB,Y ;MATCH KEYPAD TABLE ENTRY?
BEQ KPADMAT ;JUMP IF MATCH
INY ;INC TO NEXT ENTRY
INY
LDX KPADTAB,Y ;END OF TABLE?
BEQ EXIT ;EXIT FOR END OF TABLE
BNE KPADCK
;
;KEY VALUE MATCHES
;PUT NEW KEYCODE IN CH AND RESET AUTO-REPEAT
KPADMAT: TAX ;SAVE KEY VALUE
INY ;GET POKEY KEYCODE
LDA KPADTAB,Y ;A HAS KEYCODE
CMP #$FF ;VECTOR ROUTINE?
BEQ KPADFUN ;EXIT FOR VECTOR ROUTINE
CMP KPADCOD ;SAME AS PRIOR KEYCODE?
BEQ KPADSAM ;BRANCH IF SAME
STA KPADCOD ;ELSE STORE NEW KEYCODE
STA CH
LDA #TIMER ;RESET TIMER
STA KPADREP
BNE EXIT1
;
KPADDM: LDA #$C0 ;LOAD DUMMY VARIABLE
STA KPADCOD
EXIT1:
*************************************
LDA #1 ;RESET BRK PRESS FLAG
STA BRKPRS
*************************************
BNE EXIT
;SAME AS PRIOR KEY, CHECK AUTO-REPEAT
KPADSAM: LDX KPADREP ;AUTO-REPEAT EXPIRED?
DEX ;DEC TIMER
BNE KPADXX ;BRANCH IF NOT
STA CH ;STORE KEYCODE
LDA #TIMER1 ;RESET TIMER
STA KPADREP
BNE EXIT1
KPADXX: STX KPADREP
;
;EXIT THIS VBLANK INTERRUPT
EXIT: JMP 0 ;CHAIN TO DEFERRED VBLANK
TEMP: DB 0 ;TEMP VARIABLE
KPADCOD: DB 0 ;PRIOR KEYCODE
KPADREP: DB $30 ;AUTO-REPEAT TIMER
;
;IF NO $FF IN TRANSLATION TABLE, THE SeCTIONS
;ENCLOSED WITHIN *** MAY BE DELETED
*************************************
BRKPRS: DB 1 ;BREAK PRESS FLAG
;
;FUNCTION VECTOR TABLE
KPADFTB: DW KPADF1 ;F1 VECTOR
DW KPADF2 ;F2 VECTOR
DW KPADF3 ;F3 VECTOR
DW KPADF4 ;F4 VECTOR
;GET FUNCTION VECTOR
KPADFUN: DEY
LDA KPADFTB,Y
STA KPADFV+1
INY
LDA KPADFTB,Y
STA KPADFV+2
;CALL TO FUNCTION VECTOR
KPADFV: JSR 0 ;CALL TO FUNCTION
JMP EXIT
KPADF1: LDA BRKPRS
BEQ KPADFR
LDA #0 ;BREAK PRESSED
STA BREAK
STA BRKPRS
LDA #$C0 ;LOAD DUMMY KEYCODE
STA KPADCOD
KPADFR: RTS
KPADF2: LDA #OPTION
STA CONSOL
RTS
KPADF3: LDA #SELECT
STA CONSOL
RTS
KPADF4: LDA #START
STA CONSOL
RTS
**************************************
END COLDST
