DOS - Character positioning and screen buffering.

DJGPP for DOS

and

Visual Studio.NET
   But I am not interested in the CONSOLE API.
   Or it's lack of support for conio.h


I am not interested in hearing about how DOS is DEAD as a solution to this question.  I paid good money for my copy of dos and DJGPP is designed for it! :)

Shoot, all I was going to say is I used to do that sort of stuff with Borland Turbo C/C++ and they had windows you could create and manage.  This allowed one to print anywhere on the screen and if they did it right, text would not scroll.  Later, I found out that Visual C++ offers the same thing on their console applications; which I've never used.  The other alternative, which really isn't too painful is to program all this in an SDI and manage the OnPaint() call yourself.  Using a TextOut() you can print the 25 lines yourself.  It really is fairly easy to do it that way.  I know because I have a much more complex program at home I am writing that takes advantage of this, however, instead of straight text on a black background I am tiling a bitmap across the background and drawing a few other bitmpas to the screen and printing text in various different colors.  Then I have to manage all keyboard input.  I don't know what DJGPP is.  Until recently, I've done a lot of programming in DOS.

warning: initialization makes pointer from integer without a cast

or

'screen' is undeclared identifier.

what's screen?

The interrupt way is much slower, but it does basically the same thing. An advantage is that it might work better if you run in a window...

It's true that I make a pointer of an integer without a cast, so let's declare screen like:

   scr *screen = (scr *)0xB8000000;

After that 'screen' is a pointer to the actual DOS text mode video memory. Setting (*screen)[24][79].ch to 'X' will simply put an X in the lower right corner of the 80x25 screen. Setting attr to 0x07 will give the X a gray color on black background.

// temp.c

int main(void){
     typedef struct {
          char ch;
          char attr;
     } scr[25][80];

     //scr * screen = 0xB8000000;
     scr * screen = (scr *)0xB8000000;

     (*screen)[24][79].ch = 'X';
     (*screen)[24][79].attr = 0x07;

     return 0;
}

Exiting due to signal SIGSEGV
General Protection Fault at eip=000015ff
eax=b8000f9e ebx=000001c5 ecx=00000000 edx=0000033f esi=00000054 edi=0000d760
ebp=0008d740 esp=0008d730 program=F:\DJGPP\TEMP\TEMP.EXE
cs: sel=01a7  base=01c50000  limit=0009ffff
ds: sel=01af  base=01c50000  limit=0009ffff
es: sel=01af  base=01c50000  limit=0009ffff
fs: sel=017f  base=000070e0  limit=0000ffff
gs: sel=01bf  base=00000000  limit=0010ffff
ss: sel=01af  base=01c50000  limit=0009ffff
App stack: [0008d760..0000d760]  Exceptn stack: [0000d6c0..0000b780]

Call frame traceback EIPs:
  0x000015ff
  0x00002e68

Ehh... Does your program run in protected mode? That could explain a few things. In that case I would try the "interrupt" way, but I suspect the entire interrupt support is not implemented...

Another solution might be to try and change the scope of ds to include video RAM at 0x000B8000 (up to 0x000B81FF or something like that). I have absolutely no idea how you would accomplish that, though. Do you have some kind of special environment where you run your program, or is everything compiled in?

If you manage to change scope of ds to physical address 0 to 0x000B81FF, you'd have to change the initialization of screen to 0x000B8000. I'm very curious however you'll get this to work...

Aaarrgghhh.... Before someone else points out that I'm a lousy matamatician, your upper limit needs to be 0x000B8FFF.