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Index > DOS > error: processor is not able to enter 32-bit real mode

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percy_vere_uk



Joined: 11 Apr 2011
Posts: 8
Location: Dorset Uk
percy_vere_uk
Hi folks

In trying to assemble hello.asm (as below) using dosbox in a linux operating system.
At the prompt typing fasm.exe hello.asm I get the following error:

flat assembler version 1.71.17
error: processor is not able to enter 32-bit real mode

I am new to fasm so any ideas what I am doing wrong.

percy

Code:
; hello.asm - single-segment, 16-bit dos "hello world" program
;
    org  0x100        ; .com files always start 256 bytes into the segment

    ; int 21h is going to want...

    mov  dx, msg      ; the address of or message in dx
    mov  ah, 9        ; ah=9 - "print string" sub-function
    int  0x21         ; call dos services

    mov  ah, 0x4c     ; "terminate program" sub-function
    int  0x21         ; call dos services

    msg  db 'Hello, World!', 0x0d, 0x0a, '$'   ; $-terminated message    
Post 25 Apr 2014, 13:35
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CandyMan



Joined: 04 Sep 2009
Posts: 305
Location: film "CandyMan" directed through Bernard Rose OR Candy Shop
CandyMan
You trying to assemble using fasm for dos on linux. In dos, fasm uses unreal mode that is not supported by emulators. Use version for the Linux systems or assemble in DPMI.
Post 25 Apr 2014, 17:16
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freecrac



Joined: 19 Oct 2011
Posts: 117
Location: Germany Hamburg
freecrac
Hello.
I never use the DOSBox on Linux, but with the DOSBox on Windows it is possible to switch into the protected mode and back to the bigrealmode/unrealmode.

http://en.wikipedia.org/wiki/Unreal_mode
Quote:
For those operating systems, an emulator such as DOSBox is the only way to run programs designed for unreal mode.

My DOSBox configuration:
xms=false
ems=false
umb=false

Dirk
Post 26 Apr 2014, 05:56
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percy_vere_uk



Joined: 11 Apr 2011
Posts: 8
Location: Dorset Uk
percy_vere_uk
Thanks for your replies on this freecrac & CandyMan

I will have a play around and see if I can get this to work now.

percy
Post 26 Apr 2014, 13:22
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Tomasz Grysztar
Assembly Artist


Joined: 16 Jun 2003
Posts: 7623
Location: Kraków, Poland
Tomasz Grysztar
There is a minor problem with terminology that may be causing some confusion here. The unREAL mode which is used by fasm (see the linked page for a full story) is something different than the "unreal mode" as defined in that Wikipedia article. I was used to the "flat real mode" name for the latter, and I still always call it FRM to avoid the confusion with my specific unREAL mode.

The mode that fasm's used is a fully 32-bit one (that is, it has the 32-bit instruction encodings, without the 66h/67h prefixes to use the 32-bit operands and addressing) and because this mode was so rarely used (though discovered a few times independently - in my link above I tell the story of my own discovery) it is also rarely supported by emulators. The DOSBox does not emulate the 32-bit real mode, hence the error message.

Nevertheless, it is still possible to run fasm in DOSBox. You may find the advice in the thread "How do I run FASM in DOSBox?".
Post 27 Apr 2014, 16:12
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percy_vere_uk



Joined: 11 Apr 2011
Posts: 8
Location: Dorset Uk
percy_vere_uk
Tomasz

I have followed the thread that you have supplied and am now able to assemble in dosbox. The only problem was the link to 'csdpmi5b.zip' was dead but I was

able to get a copy from 'ftp.invisible-island.net-0'.

Thank you very much for this information.

percy
Post 28 Apr 2014, 12:25
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