;; This program encrypts 10 characters typed from the keyboard. Encrypted characters
;; will be stored in memory and displayed on the screen.
;;
;; Encryption Algorithm: Add 10 to the 1st character, 9 to the 2nd character,...1 to 
;; the 10th character. 
;;
        .ORIG   x3000
        LEA     R1, BUFFER    ; R1 will be pointer to buffer
        LD      R2, TEN       ; R2 will contain k, the encryption character
NEXTIN  BRnz    OUTPUT
        TRAP    x23           ; get a character to encrypt
        ADD     R0, R0, R2    ; encrypt
        STR     R0, R1, #0
        ADD     R1, R1, #1    ; increment pointer
        ADD     R2, R2, #-1   ; decrement k
        BRnzp   NEXTIN
OUTPUT  LEA     R1, BUFFER
        LD      R2, TEN
NEXTOUT BRnz    DONE
        LDR     R0, R1, #0
        TRAP    x21           ; display character
        ADD     R1, R1, #1
        ADD     R2, R2, #-1
        BRnzp   NEXTOUT
DONE    TRAP    x25
BUFFER  .BLKW   #10
TEN     .FILL   #10
        .END