;;
;; Official Kernal routine, described in:
;;
;; - [RG64] C64 Programmer's Reference Guide   - page 282
;; - [CM64] Compute's Mapping the Commodore 64 - page 230
;;
;; CPU registers that has to be preserved (see [RG64]): .Y
;;


clrchn:

	;; Handle IEC input device
	lda DFLTN
	jsr iec_devnum_check
	bcs +
	;; Previous device was IEC one - send UNTALK first
	jsr untlk
*
	;; Restore output device to default
	lda DFLTO
	jsr iec_devnum_check
	bcs +
	;; Handle IEC output device
	jsr unlsn
*
clrchn_reset: ;; entry needed by CHRIN
	;; Set input device number to keyboard
	lda #$00
	sta DFLTN
	;; Set output device number to screen
	lda #$03
	sta DFLTO

	rts