Nasm“指令预期”问题是我的编译器还是我的代码

Question

I am fairly new to NASM and I already want to blow my brains out because I dont know why I keep getting this error "instruction expected" Line 14. Is it my compiler or my code. Please help me Ive been at this for hours and I don't know what to do at this point.

section .data
  CELC DB ?
FARH DB ?
MSG1 DB 'INPUT VALUE OF CENTIGRADE','$'
MSG DB 'EQUIVALENT FARHRENEHEIT IS','$'

section .text
    global _start
section .code

_start:
    ASSUME CS:CSEG, DS:DSEG
       MOV AX,DSEG
       MOV DS,AX ; INITIALIZE DATA SEGMENT
       LEA DX,MSG1
       MOV AH, 01H
      
       INT 21H ; DISPLAY "INPUT VALUE IN CELC"
       MOV AH, 01H
      
       INT 21H ; INPUT VALUE IN CELC
       MOV CELC,AL ; MOVE THE INPUT VALUE TO 'CELC'
       MOV AL,CELC
       MOV CL,09H
       MOV CH,00H
       MUL CL ; AX=9*CELC
       MOV CL,05H

       DIV CL ; AL=AX/CL=(9*CELC)/5
       ADD AL,20H ; ADD 20H=32 TO AL TO GET FAHR
       MOV FARH, AL ; FAHR=(9*CELC)/5+32
       MOV AH,4CH
       INT 21H

Answer 1

Errors discovered in your code are almost never compiler bugs. Line 14 says ASSUME CS:CSEG, DS:DSEG which is MASM way to tell assembler which segment registers it should use for addressing segments CSEG and DSEG . But instead of those segments (alias sections ) you declared .data , .text and .code . Beside that, NASM doesn't ASSUME . Comment out Line 14 and declare sections DATA and CODE , as is usual in DOS programs.

NASM requires references to the contents of memory variables be in square brackets. Instead of
MOV CELC,AL; MOVE THE INPUT VALUE TO 'CELC' MOV CELC,AL; MOVE THE INPUT VALUE TO 'CELC' you need MOV [CELC],AL etc. Or employ unused registers BX,SI,DI instead of memory variables. BTW its better to calculate temperatures as 16bit signed integers, otherwise you are restricted to the range 0..255 degrees.

Also revise DOS function and concentrate to the proper function identificator in AH before INT 21h . You'll need AH=09h to display the prompt. Don't forget that when the user enters 5 on the keyboard, DOS function AH=1 returns 35h in AL , which is not the value you should calculate with.

I recommend to start with some HelloWorld example, learn to use TLINK and TurboDebugger in DOSBox and only when all works, add more functionality, step by step.