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is there any program written for dos that can completly clear a 320x200 screen, after a specific keypress? something like snarf but instead of saving it, it clear the screen

i have a game with a 2D engine inside it and id like to see how the screen is redraw after complete clearing...
maybe it is possible directly from dosbox ?

I checked if there is any plugin / special port of dosbox that show specific information (like the screen buffer, palette and so) but found nothing ... :(

I'm not sure. But what do you mean exactly? Like clearning the screen back in command prompt?

tl;dr
cls.exe

I belive he means a TSR. Write one yourself. Very easy with TP for example.

clr

what i mean is clearing the screen buffer when in vga mode and the game is running (by filling zeroes at 0xA000)

yep writting a TSR is one of the solutions but i dont want to spend 2 days learning dos programming and debugging a dos app

ermm... what *exactly* are you trying to do?

clear the screen buffer when the game is running, since its a 2D game and the screen is not fully refreshing every frame (not like in doom), you can actually watch how each element is redraw

i just dig into dosbox source but dont know where to start...

a single

if (GetAsyncKeyState(special_key))
{
memset(&memory[0xA000], 0);
}

should be enough

What game? Is it a game you have the source code to? Or are you trying to nuke the screen while the game is running?

You're running it in dosbox?

Could you maybe run the game under a debugger? Break into it, clear the mem, continue?

You've got the source to DOSBox - couldn't you mod it to log all writes to VGA memory? (or rather the access pattern if that's what you're interested in)

As dr_evil wrote, a TSR would be a fine solution to your problems.

Most ms-dos programs used an offscreen buffer anyway, since writing randomly to (and specially reading from) 0xA000 was so slow

(thus clearing the vidmem to see how it's redrawn would be quite pointless, since the redrawing would not happen directly on video memory)