program to add integers from 1 to n (inclusive) - using loop and input device.txt

.program to add integers from 1 to n (inclusive)
.using loop and input device F3
.2345678901234567890123
SUM2     START   1000
         LDX     INITIAL
         LDA    #0
AGAIN    TD      INDEV
         JEQ     AGAIN
         RD      INDEV
         STA     N
         LDA    #0
LOOP     ADDR    X,A
         TIX     N
         JGT     OUT
         J       LOOP
OUT      STA     ANS
INITIAL  WORD    1
INDEV    BYTE    X'F3'
N        RESW    1
ANS      RESW    1
         END     SUM2