🚀 go-pugleaf

black_phantom@my-dejanews.com wrote:
> 
>   "TK - TBD" <PISS_OFF_SPAMMERS_Thomas_Kjoernes@phoenix.com> wrote:
> > tunney <bigmacmeal@hotmail.com> wrote in article
> > <7c6u0d$cue$1@winter.news.rcn.net>...
> > > I know that this is a thick question, but could someone explain to me
> > > how to clear the screen in text and video mode, can't for the life of me
> > > figure out how. Please help me I have an exam in this soon.
> > > Also could someone explain int 21h service 0Ah
> > >
> > > Thanks a million.
> >
> > Clearing the screen (TEXTMODE) is easy:
> >
> > mov ax, 3     ; set mode 3, voilà screen is cleared.
> > int 10h               ;
> >
> > For less flickering... you could clear it by filling video mem
> > directly, like this:
> >
> > push 0B800h
> > pop es
> > xor ax, ax
> > xor di, di
> > mov cx, 16384
> > rep stosw
> >
> > For video mode, ask someone else.
> 
> I think it should be "graphics" mode, not "video" mode. It's not a lot harder.
> For CGA graphics modes the above will also work. For chained modes (MCGA 13h)
> you clear 64k starting at 0A0000h:
> 
> clear_a0000:
> mov ax, 0A000h
> mov es, ax
> sub ax, ax
> sub di, di
> mov cx, 32768
> cld
> rep stosw
> 
> For non-chained modes the above clears only bit plane selected in sequencer.
> To clear screen you need to allow write to all 4 bit planes:
> 
> mov dx, 3c4h
> mov ax, 0F02h
> out dx, ax
> 
> Of course, it's a good idea to save previous bit plane write bitmask and later

> That's all for standard VGA BIOS modes. I hope that you don't need to deal
> with non-standard modes ('X' or how is it called now?) - it's no harder just
> more dirty work.
> 
What do you mean nonstandard - the 32K 64K and true color where each
pixel is described by 2 or 3 consecutive bytes? 
I was exited about planar video memory on Amigas when they first came
out, and all I had was 4 color Commodore 64 but soon after I realized
that it is very awkward to handle.
Personaly I thing the new modes are much more elegant way of handling
the display. There is no need to access 4 different locations while
switching banks. Most high res VGAs have vesa BIOS or it is available as
a TSR.
Piece of cake.