unREAL mode

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Ninho

Joined: 07 May 2010
Posts: 16

Ninho 24 Jan 2011, 15:47

Tomasz Grysztar wrote:

bitRAKE wrote:

http://wikipedia.org/wiki/Unreal_mode wrote:
"Huge" real mode is attained by, in addition, loading the code selector (CS) from a descriptor allowing access to the whole memory and having the 32-bit attribute ("D" bit) set to one.

Who invents this nomenclature? It doesn't make any sense to me. Also, it is earlier mentioned just as a synonym to FRM (and it makes much more sense). Do you know any place where the "huge real mode" was used in the meaning of 32-bit unreal? Well, the article does not cite any sources - perhaps these days it works like "whoever gets to edit the wikipedia first, gets to invent the names".

Oh, Tomasz ! I just stumbled upon this old part of a discussion; I am the one to be blamed or praised for redacting large parts of the Wikipedia article and in particular introducing "huge real mode", but I did not invent the term, that would be contrary to WP policies - HRM was used in Ralf Brown's famous interrupt list along with his description of Helix RM386 API. That is some "source". I don't know if Ralf coined the expression by himself or Helix named it so - I suspect rather the latter. I remain guilty of not quoting my source in that article, (it's been a long time... should go back there and add a reference).

Several people I'm sure have independently come upon RM32/HRM over the years. Commercially it's been promoted by Helix and bundled without fanfare in TSR programs such as Logitech mouse drivers.

Regards !

--
Ninho

24 Jan 2011, 15:47

CandyMan

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

CandyMan 26 Oct 2014, 18:18

In 16-bit unreal mode this instruction is valid.

Code:

mov [cs:1234h],ax

In 32-bit unreal mode this instruction is valid.

Code:

mov [cs:12345678h],eax

Writting with cs override is invalid in protected mode, so it is indeed real mode.

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26 Oct 2014, 18:18

neville

Joined: 13 Jul 2008
Posts: 507
Location: New Zealand

neville 27 Oct 2014, 04:40

CandyMan wrote:

In 32-bit unreal mode this instruction is valid.
Code:
mov [cs:12345678h],eax
    

and it is also valid in 16-bit unreal mode. Wink

Edit: oops, I should've put my glasses on before shooting my mouth off Very Happy

Well, it would be valid in 16-bit unreal mode if it was an es: override, but not for the cs: override.

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27 Oct 2014, 04:40

freecrac

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

freecrac 27 Oct 2014, 14:24

neville wrote:

CandyMan wrote:
In 32-bit unreal mode this instruction is valid.
Code:
mov [cs:12345678h],eax
    
and it is also valid in 16-bit unreal mode.

Edit: oops, I should've put my glasses on before shooting my mouth off
Well, it would be valid in 16-bit unreal mode if it was an es: override, but not for the cs: override.

In 16-bit unreal mode i like to use instructions without a segment override prefix using the default segment register of DS.

Code:

xor ebx, ebx
mov bx, ds
shl ebx, 4
mov edi, 12345678h
sub edi, ebx
mov [edi],eax

27 Oct 2014, 14:24

CandyMan

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

CandyMan 27 Oct 2014, 16:08

I only wrote that in the protected mode writing with cs prefix is generating the exception.
In the real mode and unreal mode this instruction is correct. It is distinguishing the real mode than protected.
In unreal 32-bit mode this instruction is valid, but is invalid in unreal 16-bit mode.

Code:

mov [cs:12345678h],eax

He is happening this way because 64kb limit was crossed.
I am recommend to use the debugger from http://board.flatassembler.net/topic.php?p=104631#104631

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27 Oct 2014, 16:08

CandyMan

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

CandyMan 25 Nov 2015, 18:39

whether is possible to use the big stack (>64 KB) in the 32-bit flat real mode?
Results from my tests that yes. The big stack is needed for me e.g. for the recursive sorting of many elements.
Soon I am going to make the program available to tests which is using the big stack under flat mode. I don't know whether the big stack is possible on all processors Intel (works on my AMD).

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25 Nov 2015, 18:39

CandyMan

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

CandyMan 26 Nov 2015, 16:14

here big stack test program, start and write whether is working

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Last edited by CandyMan on 11 Aug 2018, 16:48; edited 1 time in total

26 Nov 2015, 16:14

Shahada

Joined: 25 Jul 2008
Posts: 77

Shahada 27 Nov 2015, 15:11

Is working.

-------------------------------------------------------------------------------------

None saw it;
Neither did Aminadab appear.

Ya Allah Ya Allah Ya Allah

27 Nov 2015, 15:11

CandyMan

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

CandyMan 05 Aug 2018, 18:50

http://www.os2museum.com/wp/a-brief-history-of-unreal-mode/

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05 Aug 2018, 18:50

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