Re: ELKS 0.0.81 available from ftp.ecs.soton.ac.uk

[David Murn]

On Sun, 14 Nov 1999, Alistair Riddoch wrote:

> I am slightly confused about the int 19h issue however. If cassette BASIC
> uses this mechanism, but is not envoked until Floppy and HDD boot have
> failed, is this what we want?

INT 19 points to a code block which tries to search for the drives then
calls INT 18 if no drives are found.  INT 18 is the vector of ROM BASIC.
You can hook to INT 19 to be booted before disks are tried to boot from.

This is how SCSI cards, etc can boot, they simply hook INT 19, try to boot
from their own disks, and return to BIOS if unable to boot.  Etherboot
has a switch so you can either boot as soon as the chip is probed, or you
can wait until INT 19 is called by BIOS to begin the boot.

Davey