;
;	REAL DUMB TERMINAL ECHO CHARACTER PROGRAM
;
;	Version 1 (USE DIRECT ADDRESSING)
;
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
;
;	PROGRAM SEGMENT BEGIN
;
	ORG	0X0000	;PROGRAM START ADDRESS
;
;	CRIN - STORE KEYBOARD CHARACTER IN MEMORY AT CHAR
;
CHRIN:	IN	STATUS	;STATUS BYTE -> A
	ANI	INMASK	;MASK DATA AVAILABLE BIT D0
	JNZ	CHRIN	;IF D0 = 1 THEN JUMP CHRIN (WAIT FOR DATA AVAILABLE)
	IN	DATA	;KEYBOARD CHARACTER -> A
	STA	CHAR	;KEYBOARD CHARACTER -> CHAR
;
;	CHROUT - OUTPUT CHARACTER IN C TO RDT SCREEN
;
CHROUT:	IN 	STATUS	;STATUS BYTE -> A
	ANI	OUTMASK	;MASK TERMINAL BUSY BIT D7
	JNZ	CHROUT	;IF D7 = 1 THEN JUMP CHROUT (WAIT FOR NOT BUSY)
	LDA	CHAR	;KEYBOARD CHARACTER -> A
	OUT	DATA	;OUTPUT KEYBOARD CHARACTER TO RDT SCREEN
;
	JMP	CHRIN	;LOOP FOR NEXT CHARACTER
;
;	PROGRAM SEGMENT END
;
;	DATA SEGMENT BEGIN
;
CHAR:	DS	1
;
;	DATA SEGMENT END
;