;
;	REAL DUMB TERMINAL ECHO CHARACTER PROGRAM
;
STATUS	EQU	1	;RDT STATUS PORT
DATA	EQU	2	;RDT DATA PORT
INMASK	EQU	0x80	;STATUS PORT BIT D0 = 7 WHEN KEYBOARD CHARACTER DATA AVAILABLE
OUTMASK	EQU	0x40	;STATUS PORT BIT D7 = 6 WHEN TERMINAL BUSY PROCESSING CHARACTER DATA
;
	ORG	0X0000	;PROGRAM START ADDRESS
;
;	CRIN - GET KEYBOARD CHARACTER INTO REGISTER C
;
CHRIN:	IN	STATUS	;STATUS BYTE -> A
	ANI	INMASK	;MASK CHARACTER DATA AVAILABLE BIT D0
	JNZ	CHRIN	;WAIT IF D0 = 1 - NO CHARACTER AVAILABLE
	IN	DATA	;KEYBOARD CHARACTER -> A
	MOV	C,A	;A->C
;
;	CHROUT - OUTPUT CHARACTER IN C TO RDT SCREEN
;
CHROUT:	IN 	STATUS	;STATUS BYTE -> A
	ANI	OUTMASK	;MASK TERMINAL BUSY BIT D7
	JNZ	CHROUT	;WAIT IF D7 = 1 - TERMINAL BUSY
	MOV	A,C	;C -> A
	OUT	DATA	;SEND CHARACTER TO TEMINAL SCREEN
;
	JMP	CHRIN	;LOOP FOR NEXT CHARACTER
;
;	PROGRAM END
;