Re: [OpenBIOS] Hello World

[David Woodhouse]

[e-mail] 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.

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David Woodhouse, Robinson College, CB3 9AN, England.   ([phone]
    [e-mail]        http://dwmw2.robinson.cam.ac.uk
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Hello World

[Oliver Xymoron]

On Wed, 11 Mar 1998, David Woodhouse wrote:
> [e-mail] said:
> > What would it take just to write a Hello World program?
>
> Ditch your fancy new SVGA cards, install an old MDA card, and

...
> 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.

It would be nearly as easy to generate output on the serial port using
polled IO. Presumably all the developers have at least a serial port and a
second machine that they're not ready to kill their BIOS on. I've recently
written a small library of assembly functions to do this, include register
and memory dump routines and a printf-like varargs function for debugging 
the bootloader of an embedded operating system I'm writing. The routines
are currently written for MASM - if anyone would like them, I can make
them available.

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