10       .OPT OBJ
20       *=  $4000
30 EOL   =   $9B
40 ; SETUP IOCB
50 OPEN  =   $03
60 WRITE =   $08
70 PUTREC =  $09
80 PUTCHR =  $0B
90 CLOSE =   $0C
0100 IOCB =  $0340   ;START OF IOCB
0110 ICCOM = $0342   ;COMMAND BYTE
0120 ICBAL = $0344   ;BUF ADDR LOW
0130 ICBAH = $0345   ;BUF ADDR HIGH
0140 ICBLL = $0348   ;BUF LENGTH LOW
0150 ICBLH = $0349   ;BUF LENGTH HIGH
0160 ICAX1 = $034A   ;READ OR WRITE
0170 ICAX2 = $034B
0180 CIOV =  $E456
0190 DEVNAM .BYTE "E:",EOL
0200 MYTEXT .BYTE "HELLO WORLD!",EOL
0210 ;
0220 OPENSCR ;       OPEN SCREEN
0230     LDX #$20    ;SECOND IOCB
0240     LDA #OPEN
0250     STA ICCOM,X
0260 ;
0270     LDA #DEVNAM&255
0280     STA ICBAL,X ;LOW BYTE SCREEN
0290     LDA #DEVNAM/256
0300     STA ICBAH,X ;HIGH BYTE SCR
0310 ;
0320 ; SET SCREEN FOR WRITE OPERATION
0330     LDA #WRITE
0340     STA ICAX1,X
0350     LDA #$00
0360     STA ICAX2,X
0370     JSR CIOV
0380 ;
0390 ; SET PUT RECORD
0400     LDA #PUTREC
0410     STA ICCOM,X
0420 ;
0430 ; SET TEXT BUFFER
0440     LDA #MYTEXT&255
0450     STA ICBAL,X
0460     LDA #MYTEXT/256
0470     STA ICBAH,X
0480 ;
0490 ; PRINT MESSAGE TO SCREEN
0500     LDA #$00
0510     STA ICBLL,X
0520     LDA #$FF
0530     STA ICBLH,X
0540 ;
0550     LDA #$FF
0560     STA $02FC
0570 LOOP JSR CIOV
0580     LDA $02FC
0590     CMP #$FF
0600     BNE QUIT
0610     JMP LOOP
0620 ;
0630 ERROR BRK 
0640 QUIT BRK 
0650     .END