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    <p>There are a few problems.</p> <p>First, you don't properly set the registers for function 0Ah. You have to set <code>bh</code> to the page number (0), and <code>cx</code> to the repeat count (1).</p> <p>Second, this BIOS function doesn't advance the cursor position and all characters get printed into the same location on the screen, overwriting each other, which should lead to only '!' visible since it's the last character.</p> <p>I advise to use function 0Eh instead.</p> <p>Third, you don't initialize the direction flag (<code>flags.df</code>) which <code>lodsb</code> relies upon. You should use <code>cld</code> to reset <code>df</code>.</p> <p>Fourth, I don't see all the code, but you should use the proper <code>org</code> directive to generate correct offsets for instructions and data.</p> <p>Also, <code>NMIs</code> and <code>SMIs</code> will cause <code>hlt</code> completion and the code that follows will execute (and what follows is your <code>Print</code>). You want to execute <code>hlt</code> in a loop.</p> <p>With these fixes we arrive at:</p> <pre><code>bits 16 org 1 jmp Start ;data fields msg db "Hello World!",0 Start: mov ax, cs mov ds, ax ; set data segment pointer cld mov si, msg ; load message to SI register call Print cli .halt: hlt ; halt the system jmp .halt Print: .PrintLoop: lodsb ; load byte from SI register or al, al ; check if 0 byte jz short .PrintDone ; if so - stop ; mov ah, 0Ah ; function - print text to cursor ; xor bh, bh ; mov cx, 1 mov ah, 0Eh ; function - print text tty int 0x10 ; BIOS interrupt jmp .PrintLoop ; continue with next char .PrintDone: ret </code></pre> <p>The binary which you get by compiling the above with <code>nasm blah.asm -f bin -o blah.bin</code> should then be loaded at <code>0x7e0:0001</code> and jumped to with <code>jmp 0x7e0:0001</code>.</p>
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    1. POData segment issue with x86 Assembler (nasm) for print function
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    1. COThanks for the post! But shouldn't it be 'org 0'? Since the program is loaded to the base address 0x7e0 with offset 0001 org 1 would furthermore cut of one byte right? The program may than print out 'ello World!'
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    2. CO`org n` sets the offset of the very first instruction or data item to `n`. If you `org 0`, load at 0, but jump to 0x7e0:1, you jump into the middle of `jmp Start` instead of the beginning. If you `org 0`, load at 0, and jump to 0x7e0:0, everything's OK. Likewise everything's OK if you `org 1`, load at 1, and jump to 0x7e0:1.
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    3. COAll clear - thanks :)
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