Programming Vga video card 
Author Message
 Programming Vga video card

I will use a video card (VGA) for my microcontroler project, so I need
to initialize the video card to enter a text mode.
I have to program in low level, because I dont use Rombios to accomplish

this.
Maybe there is an procedure in the rombios the video card to enter a
text mode.
This project is an stand alone application, so I need a monitor to debug
my
programs in my own operating system and BIOS.

Thanx in advance

David Rodrguez



Mon, 05 Aug 2002 03:00:00 GMT  
 Programming Vga video card

Quote:
>I will use a video card (VGA) for my microcontroler project, so I need
>to initialize the video card to enter a text mode.
>I have to program in low level, because I dont use Rombios to accomplish
>this.

The VGA card has its own ROM BIOS, but needs to be initialised by
the main systems BIOS (using a call to <bios segment>:0000 or
something). It will default to a textmode, and will install an 'interface'
under INT 10h.

H



Mon, 05 Aug 2002 03:00:00 GMT  
 Programming Vga video card


Quote:
>>I will use a video card (VGA) for my microcontroler project, so I need
>>to initialize the video card to enter a text mode.
>>I have to program in low level, because I dont use Rombios to accomplish
>>this.
>The VGA card has its own ROM BIOS, but needs to be initialised by
>the main systems BIOS (using a call to <bios segment>:0000 or
>something). It will default to a textmode, and will install an 'interface'
>under INT 10h.

I'm guessing, but I suspect the original questioner cannot depend on
the BIOS code, either in a "normal" system or in ROMs on the VGA
board, since they/he is using a microcontroller, probably not an x86.

Chances are good, too, that it is NOT a PCI based board for similar
reasons, so even if there were PCI FORTH code on the board (which I
suspect few boards include even though the PCI spec tries to be "non
Intel specific" by recommending such code in ROM), that's probably not
an option either.

Sounds to me like a simple, "how do I write my own program to
initialize a VGA chipset?" kind of question.

If this were an SVGA, then it would depend on the chipset and the
board it is integrated into.  Thus needing information from the chip
maker and information from the board maker, my guess.  Doubly so if
PCI.

But since I'm guessing it is ISA and VGA, there is a reasonable chance
that it will respond as a VGA and that standard docs (such as those
found in Richard Ferraro's "programmer's guide to the ega, vga, and
super vga cards") might help some.  And there may be an available
source listing of BIOS VGA initialization for text mode handy on the
net.  Not sure, though.  I believe I have IBM's BIOS listings for
their CGA and EGA, but nothing for the VGA.

David:
If you get this working well, let us know your struggles and what
resources you used to solve them.  I'm assuming you have a simple
logic interface for the ISA connector and are trying to just operate
the board as a VGA but with your microcontroller's instructions and
I/O to the connector.  I'd certainly enjoy hearing more about what is
going on.  Maybe my guesses are simply wrong.  Also, you might post
this kind of question on comp.arch.embedded since folks there deal
with questions like this, often enough.

Jon



Mon, 05 Aug 2002 03:00:00 GMT  
 
 [ 3 post ] 

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