阅读下面的程序，说明程序的功能。 DSEG SEGMENT FNAME DB 'B: / ASM/ PRNSTR.ASM'.0 BUFF DB 4000H DUP(0) ERR DB ‘PRINTER ERROR!＄‘ DSEG ENDS CSEG SEGMENT ASSUME CS:CSEG.DS:DSEG START: MOV AX. DSEG MOV DS,AX MOV DX,OFFSET FNAMT. MOV AX,3D00H INT 21H MOV BX.AX MOV CX,SIZE BUFF LEA DX,BUFF MOV AH,3EH INT 21H MOV CX,AX MOV AH,3EH JNT 21H LEA S1, BUFF CLD GETC: LODSH MOV DL. AL MOV AH,02 INT 21H MOV AL ,DL XOR DX.DX XOR. AH AH INT 17H TEST AH 09H JNZ DSPERR LOOP GETC RETDOS: MOV AX,4C00H INT 21H DSFERR: LEA DX,ERR MOV AIL 9 INT 21H JMP RETDOS CSEG ENDS END START