MIPS assembly program to read integer byte by byte

Question

I try to learn assembly by writing small programs. This MIPS program is supposed to read an integer from the terminal and print it byte by byte in hexadecimal. I think it works but I didn't check everything.

.data
prompt:     .asciiz "Enter an integer (positive or negative): "
s1:     .asciiz "B1: 
s2:     .asciiz " B2: 
s3:     .asciiz " B3: 
s4:     .asciiz " B4: 
MyNumber:       .word 0

.text
main:
    addi $v0, $zero, 4  #code 4 is to print string
    la $a0, prompt      #loads string into register
    syscall

    addi $v0, $zero, 5  #code 5 is to read an integer
    syscall

    sw $v0, MyNumber        #stores value from $v0 to input

    addi $v0, $zero, 4  #code 4 is to print string
    la $a0, s1      #loads string into register
    syscall

    la $t1, MyNumber
    lb $a0, 0($t1)
    lb $t0, MyNumber  
    addi $v0, $zero, 34
    syscall

    addi $v0, $zero, 4  #code 4 is to print string
    la $a0, s2      #loads string into register
    syscall

    lb $a0, 1($t1)  
    addi $v0, $zero, 34 #print in hexadecimal
    syscall

    addi $v0, $zero, 4  #code 4 is to print string
    la $a0, s3      #loads string into register
    syscall

    lb $a0, 2($t1) 
    addi $v0, $zero, 34
    syscall

    addi $v0, $zero, 4  #code 4 is to print string
    la $a0, s4      #loads string into register
    syscall


    lb $a0, 3($t1) 
    addi $v0, $zero, 34
    syscall 

Answer 1

Firstly, you're missing some closing quotes on the data declarations at the top of the file. And you should specify that you make use of MARS specific calls.

However, when you read an integer using the "read integer" call, you read an 8-bit integer, that is, ranging from 0 to 255.

In your program you attempt to print four bytes out of this single byte, and therefore your program will print out garbage to the console.

You should simply remove the code that prints B2, B3 and B4.