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 25 Apr 2014, 13:35

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

25 Apr 2014, 13:35

CandyMan

Joined: 04 Sep 2009
Posts: 413
Location: film "CandyMan" directed through Bernard Rose OR Candy Shop

CandyMan 25 Apr 2014, 17:16

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.

25 Apr 2014, 17:16

freecrac

Joined: 19 Oct 2011
Posts: 117
Location: Germany Hamburg

freecrac 26 Apr 2014, 05:56

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

26 Apr 2014, 05:56

percy_vere_uk

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

percy_vere_uk 26 Apr 2014, 13:22

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

26 Apr 2014, 13:22

Tomasz Grysztar

Joined: 16 Jun 2003
Posts: 8351
Location: Kraków, Poland

Tomasz Grysztar 27 Apr 2014, 16:12

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?".

27 Apr 2014, 16:12

percy_vere_uk

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

percy_vere_uk 28 Apr 2014, 12:25

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

28 Apr 2014, 12:25

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