.MCALL .READW,.WRITW FUNCTION .READ ; ; R1 IS CHANNEL ; R2 IS BUFFER ; R3 IS BYTE COUNT ; R4 IS BLOCK NUMBER ; LET R3 := R3 R.SHIFT 1 .READW #AREA,R1,R2,R3,R4 IF RESULT IS CS RETURN #-1 END LET R3 := R3 L.SHIFT 1 ;MULT BY 2 RETURN R3 FUNCTION .WRITE LET R3 := R3 R.SHIFT 1 .WRITW #AREA,R1,R2,R3,R4 IF RESULT IS CS RETURN #-1 END LET R3 := R3 L.SHIFT 1 RETURN R3 AREA: .BLKW 10 .END