ser.atn

.PAGE 'SER.ATN'
;
;
;
ATNIRQ	LDA PA1         ; CLEAR IRQ (CA1)
	LDA #1
	STA ATNPND
	RTS
;
ATNSRV	SEI
;
	LDA #0          ; CLEAR PENDING FLAG
	STA ATNPND
	STA LSNACT      ; CLEAR ADDRESS FLAGS
	STA TLKACT
;
	LDX #TOPWRT     ; RESET STACK
	TXS
;
	LDA #$80        ; SET ATN MODE FLAG FOR ACPT ROUTINE
	STA EOIFLG      ;RESET EOI FLAG TO NON-EOI STATE
	STA ATNMOD
;
	JSR CLKHI
	JSR DATLOW      ; SET DATA LINE LOW AS RESPONSE
;
	LDA PB          ; SET ATN ACK TO GET HARDWARE CONTROLL OF DATA LINE
	ORA #ATNA
	STA PB
;
ATNS15	LDA PB          ; TEST ATN STILL HERE
	BPL ATNS20      ; GONE !
	AND #CLKIN      ; CLOCK STILL LOW
	BNE ATNS15
;
;
ATN30	JSR ACPTR       ; GET A COMMAND BYTE
;
	CMP #UNLSN
	BNE ATN35
;
	LDA #0          ; GENERAL UNLISTEN COMMAND
	STA LSNACT
	BEQ ATN122      ; JMP
;
ATN35	CMP #UNTLK
	BNE ATN40
;
	LDA #0
	STA TLKACT      ; UNTALK NOW
	BEQ ATN122      ; JMP
;
ATN40	CMP TLKADR      ; OUR TALK ADDRESS?
	BNE ATN45       ; NOPE
;
	LDA #1          ; YES
	STA TLKACT      ; SET ACTIVE TALKER FLAG
	LDA #0
	STA LSNACT      ; UNLISTEN
	BEQ ATN95       ;JUMP
;
ATN45	CMP LSNADR      ; OUT LISTEN ADDRESS?
	BNE ATN50       ; NOPE
;
	LDA #1          ; YES
	STA LSNACT
	LDA #0
	STA TLKACT
	BEQ ATN95       ;JUMP
;
ATN50	TAX             ; TEST IF SA
	AND #$60
	CMP #$60        ; SA = $60 + N
	BNE ATN120      ;DID NOT GET A VALID COMMAND
;
;
	TXA             ; A SA FOR ME
	STA ORGSA
	AND #$0F        ; STRIP JUNK
	STA SA
;
	LDA ORGSA       ; TEST IF CLOSE
	AND #$F0
	CMP #$E0
	BNE ATN122      ; NO
;
	CLI
	JSR CLOSE       ; CLOSE THE FILE
	SEI
;
; WARNING:::CLOSE DOESN'T RETURN IN TIME FOR ATN122:::
;
ATN95	BIT PB          ; TEST ATN STILL HERE
	BMI ATN30
;
;
; ATN GONE , DO WHAT WE WHERE TOLD TO DO
;
;
ATNS20	LDA #0          ; CLEAR ATN MODE
	STA ATNMOD
;
	LDA PB          ; ATN GONE , RELEASE ATN ACK
	AND #$FF-ATNA
	STA PB
;
	LDA LSNACT      ; LISTEN ?
	BEQ ATN100
;
	JSR LISTEN
	JMP IDLE
;
ATN100	LDA TLKACT      ; TALK?
	BEQ ATN110
;
	JSR DATHI       ; RELEASE DATA LINE
	JSR CLKLOW      ; PULL CLOCK LOW
;
	JSR TALK
ATN110	JMP ILERR       ; RELEASE ALL LINES AND GO TO IDLE
;
; FIX SO (DEVICE NOT PRESENT) ERRORS REPORTED
;
ATN120	LDA #$10        ;KILL ALL BUT ATNAK
	STA PB
ATN122	BIT PB
	BPL ATNS20      ;EXIT OUT SAME WAY AFTER ATN DONE
	BMI ATN122      ;JMP
;
.END
; RSR 12/8/80 FIX INVERTED LOGIC
; RSR 12/16/80 FIX BAD LOGIC
; RSR 12/31/80 FIX EOIFLG AND LOGIC