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    <p>I think the problem is likely to be related to the origin specified.</p> <pre><code>[ORG 0x7C00] ;Origin, tell the assembler that where the code will </code></pre> <p>Based on the conversation we've been having it appears that the address isn't as predicted in some way. It might simply that DS the data segment register is not what you expect. You might actually be able to get the original listing from the web page to work by adding a push and pop of ds before the call to display the string like this,</p> <pre><code> push cs pop ds </code></pre> <p>If not the following code works. </p> <pre><code> [ORG 0x000] ; switched to 0 since we are going to try to correct it ourself call nextinstruction nextinstruction: ; get the return address of the call into dx pop dx ; which is essentially the start of the code + 3 (3 bytes for the call instruction) MOV SI, HelloString ;Store string pointer to SI add si, dx ; add IP from start of program sub si, 3 ; subtract the 3 the call instruction probably took push cs pop ds ; make ds the same as cs. CALL PrintString ;Call print string procedure JMP $ ;Infinite loop, hang it here. </code></pre> <p>This code figures out the offset at runtime of the code being run and also makes sure DS is point to the same segment. Unless otherwise noted instructions involving SI generally also use DS as their code segment to reference the memory.</p> <p>DS is a segment register and you might want to read something like the <a href="http://homepage.mac.com/randyhyde/webster.cs.ucr.edu/www.artofasm.com/index.html" rel="nofollow noreferrer">Art of Assembly</a> to learn more.</p> <p>Earlz is also doing the same sort of thing, just making sure the registers are correct so that the memory address is referenced correctly. It's just he knows more about the boot sector specifics than me.</p>
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    1. POHello World bootloader not working
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    1. USColin Newell
    1. USColin Newell
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      1. VTUpMod
    1. COLike I said, tutorial 2 works fine, proving that the BIOS is set up correctly for booting from a floppy. It's only when it's told to do NOTHING BUT HANG (tutorial 1) that the BIOS ignores it. I have to be honest I'm new to this whole bootloading thing - this tutorial is all that I've done. I assumed I *was* loading via the boot sector - what makes you think I'm not? Also, as the tutorial expains, the program is compiled using NASM into a raw binary file (not a COM file). But I'll give your suggestion a try anyway.
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      1. USDarkOwl
    2. COTrue, I misinterpretted what you said. In that case I suspect the origin is still the cause of the problem, but figuring out the actual cause is likely to require printing out the register IP to figure out the actual origin. I'll see if I can come up with something to help.
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      1. USColin Newell
    3. COOK, I've tried your sugestion. I still don't get "Hello World", but I don't get that unusual face character anymore either. I simply get a blinking cursor towards the top-left (as opposed to the bottom corner, where the unusual character has previously been).
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      1. USDarkOwl
 

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