Illegal Memory Reference

Question

I'm a beginner in the Assembly Language
trying to Implement STRCPY
My Assembler "TASM" returns an " Illegal Memory Reference" Error.. and tried to read about the error but couldn't find anything.

Here's ma Code.

include inout.asm
.Model Small,c
.486
.STACK 200h
.DATA
    Arr1 DB "ABCD$"
    Arr2 DB "EFGHIJ$"
.CODE
StART: MOV AX, @DATA
       MOV DS, AX

      LEA Si,Arr1
      LEA Di,Arr2

again:  cmp Byte PTR [Si], "$"
        JNE Ite ; Iterate
        JMP Done
         Ite: MOV Byte PTR[ Di ],[Si] ; Error Here
         Inc Si ; One Byte though
         Inc Di ; One Byte though
         JMP again
Done: MOV Byte PTR [Di], "$"
      call puts, offset Arr2
      Call puts, offset Arr1
 MOV AH,04CH
 MOV AL,0
 INT 21h
 END START

and here's what the Assembler says..

C:\TASM\BIN>tasm /zi /z third
Turbo Assembler  Version 3.1  Copyright (c) 1988, 1992 Borland International

Assembling file:   third.ASM
                 Ite: MOV Byte PTR[ Di ],[Si] ; Error Here
**Error** third.ASM(18) Illegal memory reference
Error messages:    1
Warning messages:  None
Passes:            1
Remaining memory:  415k

btw I tried

MOV Byte PTR[DI],BYTE PT[SI] but didn't work

Answer 1

Such operation isn't allowed in asm x86. You can't move data directly from one memory cell to another. In order to do that you need to go through a register, e.g.:

mov al, byte ptr[di]
mov byte ptr[si], al

Answer 2

As icepack points out, what you have there is not a valid instruction.

Check out the movs instruction, though, which will move the byte from [si] to [di] and also increment both index counters.