improved initialization and Kernal vector handling

c64/kernal/cint.s

@@ -43,6 +43,9 @@ cint:
 	;; Put non-zero value in enable_case_switch
 	stx enable_case_switch
 	
+	;; Set default I/O devices (see SCINIT description at http://sta.c64.org/cbm64krnfunc.html)
+	jsr clrchn_reset
+	
 	;; Fallthrough/jump to screen clear routine (Compute's Mapping the 64 p215)
 	jmp clear_screen
 

c64/kernal/clrchn.s

@@ -10,24 +10,24 @@
 
 clrchn:
 
-	;; Restore input device to default
+	;; Handle IEC input device
 	lda DFLTN
 	jsr iec_devnum_check
 	bcs +
 	;; Previous device was IEC one - send UNTALK first
 	jsr untlk
 *
-	;; Set input device number to keyboard
-	lda #$00
-	sta DFLTN
-
 	;; Restore output device to default
 	lda DFLTO
 	jsr iec_devnum_check
 	bcs +
-	;; Previous device was IEC one - send UNLISTEN first
+	;; Handle IEC output device
 	jsr unlsn
 *
+clrchn_reset:
+	;; Set input device number to keyboard
+	lda #$00
+	sta DFLTN
 	;; Set output device number to screen
 	lda #$03
 	sta DFLTO