[OpenBIOS] Hello World

[David Woodhouse]

cpa at hopper.unh.edu said:
>  What would it take just to write a Hello World program?

Ditch your fancy new SVGA cards, install an old MDA card, and 
	mov ax,b800h
	mov ds,ax
	mov ax,'eH'
	mov [0],ax
	mov ax,'ll'
	mov [2],ax
         ...

  OK, I'm a bit rusty, but you get the idea.

The MDA cards require absolutely no setup. They display text from the moment
the power goes on. I suspect older [CEV]GA cards will be similar.

> I think
> seeing this code would give people something of a starting place. Do
> we just load the Video BIOS up and use it to write a string to the
> screen and halt, or   can/should we do it without the Video BIOS?

Until we've set up enough to support the card's Video BIOS, we'd better do it 
on our own. Most new cards will probably require at least the PCI BIOS 
functions to have been implemented first.

> From there you can add support to initialize your chipsets functions.

> BTW, do we have anybody here with a SMP machine? Those do require more
> to initialize, and we will eventually want to make sure that works. 

Yep. I've got such a beast. I'm not playing until May, when my Finals are 
over, but after that I'll be working on it. You'd be surprised at just how 
little the SMP Tyan BIOS manages to do for itself - that's half the reason I 
wanted us to write our own in the first place.


----                              ----                              ----
David Woodhouse, Robinson College, CB3 9AN, England.   (+44) 0976 658355
    Dave at imladris.demon.co.uk        http://dwmw2.robinson.cam.ac.uk
	    finger pgp at dwmw2.robinson.cam.ac.uk for PGP key.



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