4-P2 Modify the following Example to accept a string and display the binary equi

Question

4-P2 Modify the following Example to accept a string and display the binary equivalent of the input string. As in the example, the user should be queried about program termination:

Needs to be in ASSEMBLY.

;Binary equivalent of characters BINCHAR.ASM
;
; Objective: To print the binary equivalent of
; ASCII character code.
; Input: Requests a character from keyboard.
; Output: Prints the ASCII code of the
; input character in binary.
%include "io.mac"
.STACK 100H  
.DATA
char_prompt db "Please input a character: ",0
out_msg1 db "The ASCII code of '",0
out_msg2 db "' in binary is ",0
query_msg db "Do you want to quit (Y/N): ",0

.CODE
.STARTUP
read_char:
PutStr char_prompt ; request a char. input
GetCh AL ; read input character
nwln
PutStr out_msg1
PutCh AL
PutStr out_msg2
mov AH,80H ; mask byte = 80H
mov ECX,8 ; loop count to print 8 bits
print_bit:
test AL,AH ; test does not modify AL
jz print_0 ; if tested bit is 0, print it
PutCh '1' ; otherwise, print 1
jmp skip1
print_0:
PutCh '0' ; print 0
skip1:
shr AH,1 ; right-shift mask bit to test
; next bit of the ASCII code
loop print_bit
nwln
PutStr query_msg ; query user whether to terminate
GetCh AL ; read response
nwln
cmp AL,'Y' ; if response is not 'Y'
jne read_char ; read another character
done: ; otherwise, terminate program
.EXIT

Explanation / Answer

STACK 100H  
.DATA
char_prompt    db "Please input a character: ",0
out_msg1       db "The ASCII code of '",0
out_msg2       db "' in binary is ",0
query_msg      db "Do you want to quit (Y/N): ",0

.CODE
        .STARTUP
read_char:
        PutStr char_prompt ; request a char. input
        GetCh   AL           ; read input character
        nwln
        PutStr out_msg1
        PutCh   AL
        PutStr out_msg2
        mov     AH,80H       ; mask byte = 80H
        mov     ECX,8        ; loop count to print 8 bits
        lea dx,msg
        mov ah,9
       int 21h
       lea dx,strb
        mov ah,0ah
        int 21h
        mov ah,4ch ;
        int 21h;

print_bit:
        test    AL,AH        ; test does not modify AL
        jz      print_0      ; if tested bit is 0, print it
        PutCh   '1'          ; otherwise, print 1
        jmp     skip1
print_0:
        PutCh   '0'          ; print 0
skip1:
        shr     AH,1         ; right-shift mask bit to test
                             ; next bit of the ASCII code
        loop    print_bit  
        nwln
        PutStr query_msg    ; query user whether to terminate
        GetCh   AL           ; read response
        nwln
        cmp     AL,'Y'       ; if response is not 'Y'
        jne     read_char    ; read another character
done:                        ; otherwise, terminate program
        .EXIT

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