NETBOOT boot code problem

["Holger Stegemann" <hs@cool.de>]

Hi,

 

I was not able to boot with NETBOOT without a graphics

card installed. I had the same problems now with some

very old VGA card (ET3000 based) installed, and I think

I figured out where the problem is.

 

With the VGA card installed, I received an error message

"Loader error: data", so I checked the boot code. It seems

to be generated when a RAM space checking is done.

The address space used seems to be the problem.

 

In the bootimage code in file ldram.inc, the address space for

interrupt vectors $E0 to $EF is used to store 'passing values'.

This address spaced is normaly only used by operating

systems and IBM ROM Basic. Unfortunately, the old VGA

BIOS seems to use this vector adress space, too. Maybe

(this is only an idea) without a graphics card installed, the

main BIOS tries to boot some BASIC code from this

address or something else.

 

Anyway, it seems to be a problem to use this address

space to store values - it simply isn't a safe address.

 

Gero, could you please check whether you could

use some other address space to store the values?

I think it would be possible to boot a VGA-less client then.

 

Holger