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CPM OPERATING SYSTEMS/CPM 68K/1.0X SOURCES/v101/c/lib7/putchar.s

@@ -0,0 +1,22 @@
+* write one char to the crt
+*  call with:  ascii char to write in D0
+status1:	.equ		$3ff01	//really $3ff01
+port1:		.equ		$3ff03	//really $3ff03
+
+			.globl	_putchar
+			.text
+_putchar:
+			move.l	(sp)+,A1	//return address
+			move	(sp),R0		//char to send
+			move	#1,R1
+			move.l	#status1,A0
+loop1:		btst	R1,(A0)	//test transmitter empty
+			beq		loop1		//not empty
+			move.b	R0,2(A0)	//send char
+			cmp.b	#$0a,R0		//line feed?
+			bne		l0
+			move.b	#$0d,R0		//carriage return
+			bra		loop1
+l0:
+			jmp		(A1)	//return
+			.end