From:	"John M. Aldrich" <fighteer AT cs DOT com>
Newsgroups:	comp.os.msdos.djgpp
Subject:	Re: DJGPP help!
Date:	Fri, 27 Sep 1996 18:29:30 -0700
Organization:	Three pounds of chaos and a pinch of salt
Lines:	54
Message-ID:	<324C7F7A.7120@cs.com>
References:	<52fp71$p09 AT news DOT inconnect DOT com>
Reply-To:	fighteer AT cs DOT com
NNTP-Posting-Host:	ppp211.cs.com
Mime-Version:	1.0
To:	Stuart Thorpe <sthorpe AT inconnect DOT inconnect DOT com>
To:	djgpp AT delorie DOT com
DJ-Gateway:	from newsgroup comp.os.msdos.djgpp

Stuart Thorpe wrote:
> 
> 1) I am new to DJGPP but have used Watcom for some time. I was unable to
>    find a FAQ so part one is where is the FAQ?

ftp://ftp.simtel.net/pub/simtelnet/gnu/djgpp/v2/faq201b.zip

The FAQ comes in 3 versions:  text, HTML, and info.  The info version
is easiest to use and you can read it by using the DJGPP info viewer
found in the 'v2gnu/txi360b.zip' package.

You can also read the FAQ online on http://www.delorie.com/djgpp

> 2) I have a series of prograrms that I have made in DOS under Watcom and
>    a little Borland C. Some of my friends have expressed interest in me
>    converting them to linux. The best way to do that I see is by using
>    DJGPP (question number 2 is, is this a true conculsion?).

DJGPP uses GNU C, which _is_ compatible with linux gcc.  However,
using any hardware-dependent operations in your program may cause
serious complications when it is compiled on a Linux box.  As
long as you're just doing text-based apps, it should be no problem.

> 3) After installing and getting "started" getting code transfered over I
>    have found myself not able to access A000:0000 for my graphics stuff
>    I am just tring to do some simple 320x200x256 mode stuff and I am
>    at a loss. I found something about a SVGA lib? What is this lib? does
>    it come with DJGPP? How do I use it? If someone could give me a simple
>    code on getting into 320x200 mode and putting a simple white dot on the
>    screen I am sure I can figure the rest out (and I can't stress this next
>    part enough... PLEASE NO ASSEMBLY) Everything I do must be in true
>    C. If this works the program will be ported to as many OS's as I can.

Direct memory access is not possible under protected-mode operation
without the use of some special mechanisms.  That's the whole reason
why 'protected mode' exists.

The FAQ covers this (and many other graphics-related issues) in chapter
10 (specifically 10.2).  A related chapter is 18, which discusses many
hardware-interface issues that trap beginning DJGPP users.

Hope this helps!

-- 
John M. Aldrich <fighteer AT cs DOT com>                      

* Anything that happens, happens.
* Anything that, in happening, causes something else to happen,
  causes something else to happen.
* Anything that, in happening, causes itself to happen again, happens
  again.
* It doesn't necessarily do it in chronological order, though.
 
                                       --- Douglas Adams

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