Writing a string to a file gives output with weird characters in assembly

I am trying to save my string to a file in assembly but it gives me this weird output with "ver 2.40 (all kinds of special characters)"

This is what I do:

mov ah,09
mov dx,200
int 21
int 20

e 200 "Test$"
n test.com
r cx
:0009
w
q

It saves it succesfully and it also runs fine when I don't exit the program and use "g" but when I "q" and try to run test.com it gives me the output I mentioned.

Solution

I presume you're using DEBUG.EXE.

After e 200 "Test$" do a d 200. You see the memory dump beginning at offset 200. This looks like:

16C7:0200  54 65 73 74 24 00 00 00-00 00 00 00 00 00 00 00   Test$...........
16C7:0210  00 00 00 00 00 00 00 00-00 00 00 00 00 00 00 00   ................
16C7:0220  00 00 00 00 00 00 00 00-00 00 00 00 00 00 00 00   ................
16C7:0230  00 00 00 00 00 00 00 00-00 00 00 00 00 00 00 00   ................
16C7:0240  00 00 00 00 00 00 00 00-00 00 00 00 00 00 00 00   ................
16C7:0250  00 00 00 00 00 00 00 00-00 00 00 00 00 00 00 00   ................
16C7:0260  00 00 00 00 00 00 00 00-00 00 00 00 00 00 00 00   ................
16C7:0270  00 00 00 00 00 00 00 00-00 00 00 00 00 00 00 00   ................

Now count the offset up until you reach the 24: 200, 201, 202, 203, 204 - You want to store the memory from offset 100h until 204h, this are 105h bytes (204h-100h+1).

This value is to be stored in CX:

r cx
:0105

With w you write CX bytes.