Write an assembly language program that will 1 read in 2 uns

 Write  an  assembly  language program that will    1)   read in 2 unsigned hex numbers, each consisting of 1 to 4 hex digits, on two lines,  2)   compute their sum,    3)   output the sum in hex on the next line,  4)   repeat step 1 until a <CR> is typed.  You may assume that only capital letters for A, B, C, D, E, and F   are used.  The numbers may have 1 to 4 hex digits.           An example of a program run is:  C/>PROG4 ?A45 ?4B 0A90 ?FFFF ?1 0000 ?  C/> 

Solution

A)

.MODEL SMALL
.STACK 100H

.DATA

PROMPT_1 DB 0DH,0AH,\'Enter the first Hex number ( 0000 - FFFF ) : $\'
PROMPT_2 DB 0DH,0AH,\'Enter the second Hex number ( 0000 - FFFF ) : $\'
PROMPT_3 DB 0DH,0AH,\'The SUM of given Hex numbers in Hex form is : $\'
ILLEGAL DB 0DH,0AH,\'Illegal character. Try again.$\'
COUNT DB ?
VALUE DW ?
.CODE
MAIN PROC
MOV AX, @DATA
MOV DS, AX
JMP @START_2   
@START_1:
LEA DX, ILLEGAL   
MOV AH, 9
INT 21H
@START_2:   
LEA DX, PROMPT_1   
MOV AH, 9
INT 21H
XOR BX, BX
MOV COUNT, 30H
@START_3:
MOV AH, 1
INT 21H
CMP AL, 0DH
JNE @SKIP_1   

CMP COUNT, 30H
JBE @START_1   
JMP @END_1   
@SKIP_1:   
CMP AL, \"A\"
JB @DECIMAL_1   
CMP AL, \"F\"
JA @START_1
ADD AL, 09H   
JMP @OK_1   
@DECIMAL_1:
CMP AL, 30H   
JB @START_1   
CMP AL, 39H
JA @START_1   
@OK_1:
INC COUNT
AND AL, 0FH   
MOV CL, 4   
SHL AL, CL   
MOV CX, 4   
@LOOP_1:
SHL AL, 1   
RCL BX, 1   
LOOP @LOOP_1   
CMP COUNT, 34H
JE @END_1   
JMP @START_3
@END_1:
MOV VALUE, BX   
LEA DX, PROMPT_2   
MOV AH, 9
INT 21H
XOR BX, BX   
MOV COUNT, 30H   
@START_4:
MOV AH, 1   
INT 21H
CMP AL, 0DH   
JNE @SKIP_2
CMP COUNT, 30H   
JBE @START_1
JMP @END_2
@SKIP_2:
CMP AL, \"A\"
JB @DECIMAL_2
CMP AL, \"F\"
JA @JUMP
ADD AL, 09H   
JMP @OK_2   
@DECIMAL_2:
CMP AL, 30H   
JB @JUMP   
CMP AL, 39H
JA @JUMP
JMP @OK_2   
@JUMP:   
JMP @START_1
@OK_2:   
INC COUNT   
AND AL, 0FH   
MOV CL, 4
SHL AL, CL
MOV CX, 4   
@LOOP_2:   
SHL AL, 1   
RCL BX, 1   
LOOP @LOOP_2   
CMP COUNT, 34H
JE @END_2   
JMP @START_4   
@END_2:
LEA DX, PROMPT_3   
MOV AH, 9
INT 21H
ADD BX, VALUE
JNC @SKIP
MOV AH, 2
MOV DL, 31H
INT 21H   
@SKIP:
MOV COUNT, 30H   
@LOOP_3:
XOR DL, DL   
MOV CX, 4
@LOOP_4:
SHL BX, 1
RCL DL, 1   
LOOP @LOOP_4   
MOV AH, 2
CMP DL, 9   
JBE @NUMERIC_DIGIT
SUB DL, 9   
OR DL, 40H   
JMP @DISPLAY
@NUMERIC_DIGIT:   
OR DL, 30H   
@DISPLAY:
INT 21H   
INC COUNT
CMP COUNT, 34H   
JNE @LOOP_3
@END:   
MOV AH, 4CH
INT 21H
MAIN ENDP
END MAIN