How to fix “error:cannot generate COM file, stack segment present”?

Question

I've been trying to fix my code for a while, but I can't seem to get it to work.It always tells me error:cannot generate COM file, stack segment present. Any ideas how I can fix this?

Here's my code:

.model small
.386
.stack 100h
.data
     inpM db "Input string: $"
     input db 19              ; max allowed 20
              db ?                ; # char entered
              db 19 dup(0)   ; chars entered
     output db 19 dup("$")
.code
start:    mov ax, @data
            mov ds, ax

            mov ah, 9              ; print inpM
            lea dx, inpM
            int 21h

            mov ah, 0Ah         ; get input
            lea si, input
            mov dx, si
            int 21h

            mov cl, [si+1]        ; reverse
            mov ch, 0
            add si, cx
            inc si
            lea di, output

rev:      mov al, [si]
            mov [di], al
            dec si
            inc di
            loop rev

again:  mov ah, 6         ; clrscr
            mov al, 0
            mov cl, 0
            mov ch, 0
            mov dl, 4Fh
            mov dh, 18h
           mov bh, 0Fh
           int 10h

          mov ah, 0
          mov bh, 0
          mov dl, 27h            ; column
          mov dh, 0               ; row

          mov ah, 9               ; print output
          lea dx, output
          int 21h

          mov bx, 20000       ; delay
l1:       mov cx, 0Fh

l2:      dec bx
          loop l2
          jnz l1

          add dh, 1                ; adds 1 to row

          loop again

          mov ah, 4Ch
          int 21h
end start

Additional info: My code reverses a string input then displays it in rows with a delay. Hoping to find out what's the cause of the error and how I'll be able to fix it.

Answer 1

I'm assuming from the error you are using TASM and TLINK to build this as a .COM program and not an EXE. Things you need to be aware of:

• COM programs should use the tiny model, not small .
• COM programs need to start with an ORG of 100h after you start the .code segment.
• The stack in a COM program starts from the top of the segment the code runs in so setting the stack size needs to be removed.
• You no longer need to set up DS as you would with building an EXE file since CS=DS=ES=SS with a COM program.

With those things in mind, you can modify the top of your code to appear like this:

.model tiny
.386
.data
     inpM db "Input string: $"
     input db 19              ; max allowed 20
              db ?                ; # char entered
              db 19 dup(0)   ; chars entered
     output db 19 dup("$")
.code
org 100h
start:
        mov ah, 9              ; print inpM
        lea dx, inpM
        int 21h

        ...

You can then build it with:

tasm myprg.asm
tlink /t myprg.obj