5、试编写完整汇编语言程序，实现由键盘输入一字符串与预设的字符串进行比较，如相等则显示"Pass",若不相等则显示"Try again，

在汇编语言中，编写这样的程序通常需要考虑几个步骤，包括接收用户输入、存储数据、进行比较以及输出结果。这里是一个基于x86汇编语言的基本示例，使用NASM语法，并假设我们有一个预设的字符串在内存的某个位置。这个例子仅用于教学目的，实际应用可能需要更复杂的错误处理。

section .data
    input_prompt db 'Enter a string: ',0
    pre_set_str db 'Hello, world!',0
    result_msg db 'Pass',0
    retry_msg db 'Try again.',0
    buffer times 20 db 0 ; Enough space for user input
    pre_set_len equ $-pre_set_str

section .bss
    input_len resb 1 ; Buffer size to store length of the input

section .text
    global _start

_start:
    ; Display input prompt
    mov eax, 4       ; sys_write
    mov ebx, 1       ; stdout
    mov ecx, input_prompt
    mov edx, len(input_prompt)
    int 0x80          ; Call kernel

    ; Read user input
    mov eax, 3       ; sys_read
    mov ebx, 0       ; stdin
    mov ecx, buffer
    mov edx, 20      ; max input length
    int 0x80          ; Call kernel
    mov byte [input_len], al ; Store the length of the input in bytes

    ; Compare strings
    lea edi, [buffer + 1] ; Skip the null terminator
    cmp edi, buffer + input_len   ; Compare pointer to end of buffer
    jae strings_not_equal    ; If not equal yet, continue comparing

    ; Strings are equal
    mov eax, 4
    mov ebx, 1
    mov ecx, result_msg
    mov edx, len(result_msg)
    int 0x80
    jmp exit

strings_not_equal:
    ; Strings are not equal
    mov eax, 4
    mov ebx, 1
    mov ecx, retry_msg
    mov edx, len(retry_msg)
    int 0x80
    jmp start_over

start_over:
    ; Loop back to start for another try

exit:
    ; Exit program (not shown)

len:
    xor eax, eax
    repnz scasb
    inc eax
    ret

; Note that this is a very simple example and doesn't include error handling or padding for newline characters.