__asm {
        mov eax, a_character        // move address of a_character into eax register
        mov al, [eax]               // copy a_character into last 8 bits of eax register
        cmp al, '$'                 // compare '$' with the a_character stored in last 8 bits of eax
        je endLoop                  // if a_character is '$, jumps to the loop end
        cmp al, 'a'                 // compare 'a' with a_character
        jl numberCheck              // if a_character has value of less than 97, jump to end of numberCheck
        cmp al, 'z'                 // compare 'z' with a_character
        jle endLoop                 // if a_character is between value of 97 and 122, jump to end of loop
    numberCheck :                   // numberCheck label
        cmp al, '0'                 // compare '0' with a_character
            jl letterCheck          // if a_character has a value less than 48, jump to end of letterCheck
            cmp al, '9'             // compare '9' with a_character
            jle endLoop             // if a_character has value between 48 and 57, jump to end of loop
    letterCheck :                   // letterCheck labels
        cmp al, 'A'                 // compare 'A' with a _character
            jl retry                // if a_character has value less than 65, display loop message and enter loop again
            cmp al, 'Z'             // compare 'Z' with a_character
            jle endLoop             // if a_character is between the value of 65 and 90, jump to end of loop

            retry :                 //retry function
    }