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flat assembler > IDE Development > Please set the inital values of AX and BX registers to zero

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TomCat



Joined: 28 May 2017
Posts: 4
Location: Hungary
Please set the inital values of AX and BX registers to zero
FASMD is the ideal tool for a sizecoder. It's great, it's fast and easy to code with it.

The only pain for me, that I have to exit after every compile (CTRL+F9) and than run the compiled code from DOS prompt.

Because if I use compile and run (F9) the inital values of AX and BX registers are 65535 (instead of 0).

It would be a great help, if you could fix this in the next release.
Many 256 byte sizecoder from the demoscene would be happy with it.

Thank you for your effort in advance.

Best regards,
Tamas Kaproncai
Post 31 May 2017, 18:18
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Tomasz Grysztar
Assembly Artist


Joined: 16 Jun 2003
Posts: 6436
Location: Kraków, Poland
I'm not sure if I could have any control over what initial register values DOS passes to the program when I use function 4Bh of int 21h to execute one. This may also depend on a DOS version/variant.
Post 31 May 2017, 20:22
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TomCat



Joined: 28 May 2017
Posts: 4
Location: Hungary
I use FreeDOS btw. From a bootable USB drive made by Rufus (https://rufus.akeo.ie).
Post 04 Jun 2017, 09:37
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zhak



Joined: 12 Apr 2005
Posts: 473
Location: Belarus
Hmm I don't get how initial register values can affect your program. Do you depend on AX/BX = 0 on exec start? If yes, then it's not correct, I suppose. Anyway, Ralph Brown gives some info an registers usage, so it seems to work as expected http://www.ctyme.com/intr/rb-2939.htm. You probably could hook the vector and clear registers yourself before exiting, but not sure if this would be the correct approach
Post 04 Jun 2017, 10:11
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TomCat



Joined: 28 May 2017
Posts: 4
Location: Hungary
Tomasz,
Acording to RalfBrown you could control the inital value of AX register by the ES:BX parameter block. You should give a valid drive letter in first FCB and second FCB.
Then AX will be zero instead of 0FFFFh. And who knows... maybe BX allways has the same value as AX.
Post 23 Jul 2017, 21:13
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TomCat



Joined: 28 May 2017
Posts: 4
Location: Hungary
oh, and i'm compiling a .com file
Post 23 Jul 2017, 21:16
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