Subject: Re: Protected Mode
Date: Fri, 24 Jul 1998 15:35:48 -0400
From: "Bean"
Newsgroups: comp.lang.pascal.borland
>I do not know much about protected mode and I never used it before. What
must I
>do to use it and what is the main-difference? I heard you can access all
memory
>of the computer with it very simply...
>
If you have BP7.0 then you only have to change target from real to
protected.
Protected mode has the following properties:
Creates DPMI applications
Can use all memory (64Meg max I think) for the Heap only
Still has 64K segments, so you can't just create huge arrays
Does not support overlays (all units load at startup).
Code segments are write protected (this means no self-modifying code)
Data segments are range restricted.
If you go outside of an array range with range checking off you get
a page-fault error.
There are very few other things you have to change. However if you must use
the heap to take advantage of the extra memory. The data segment is still
only 64K max.
I believe that programs actually run slightly slower in protected mode
because of the way segments are handled, and because the processor must
change from protected mode to real mode to do all bios code. (Someone
please correct me if I as wrong about this).
Most of my programs that I compiled in protected mode needed very little
modifications if any.
Hope this helps,
Bean, thitt@igateway.com
------------------------------------------------------------------------------
Subject: Q: Swap-file via RTM.EXE (DPMI)
Date: Tue, 04 Aug 1998 08:37:33 +0100
From: Bernd Heutling
Organization: RRZN - Newsserver
Newsgroups: comp.lang.pascal.borland
Hi all,
again I got stuck and I'd be grateful if you could help me.
In protected mode you've got lots of memory but sometimes it is still
not
enough. After some time I found a source (sorry, it's German: "Zauber-
künstler DPMI" by Sen Letzel, DOS Toolbox 4/93, pp34-37) which showed me
how to initialize a swapfile on the harddisk of up to 2 GByte. That uses
undocumented functions in RTM.EXE ... I know, I know .... :-(
Anyway, after initializing the Init-function returns
rtmOk = successfully finished
rtmNoMemory = not enough space on the disk
rtmFileIOError = unspecified I/O-error
I've used this successfully for a long time (see date of literature) but
now I'm more and more encountering problems.
And this is the problem: since there is no interface of the RTM.EXE
(understandably) I do not know what values are equal to the constants
and
so I do not know what error I bumped into.
Does anybody know which constant has which value? (By the way, the data
format of the function-return is integer.)
Thank you very much in advance.
Bernd Heutling
--------------------------------------------------------------------------------
Subject: Re: Q: Swap-file via RTM.EXE (DPMI)
Date: Tue, 4 Aug 1998 09:39:29 +0100
From: Pedt Scragg
Organization: Working in Chaos
Newsgroups: comp.lang.pascal.borland
In article <35C6BA3D.4B16@mbox.ikph.uni-hannover.de>, Bernd Heutling
writes
>Anyway, after initializing the Init-function returns
> rtmOk = successfully finished
> rtmNoMemory = not enough space on the disk
> rtmFileIOError = unspecified I/O-error
>Does anybody know which constant has which value? (By the way, the data
>format of the function-return is integer.)
>
For Open:
rtmOK = 0
rtmNoMemory = 1
rtmFileIOError = $22
--
Pedt Scragg
Never curse the Crocodile's mother before crossing the river
(
geocities.com/SiliconValley/2926) (
geocities.com/SiliconValley)