[syslinux] Comboot files

[Michael K Ter Louw]

Hi,

There’s not much to say about making a .cbt file. Here’s some things
that come to mind, though:

	- start your program with an org of 0x100 (use [org 0x100] in
nasm)
	- make all jumps/accesses NEAR and _relative_
	- the program shouldn't use a total of more than 64kb of memory
	- use standard BIOS calls when possible (to make sure your
program
	  will run on the most hardware)
	- quit back to syslinux by invoking int 0x20

If you would like an example of a comboot program, see the one I've
created at www.bootscriptor.org.  The source code is available so you
can see how it does certain things like process command-line input from
Isolinux, etc.  HPA has worked to make the comboot programs operate just
like .com programs in DOS, so when in doubt...do as you would in DOS
(lots of stuff on the web for that).  Just make sure you don't call any
DOS API functions (i.e. int 0x21) as it will cause Syslinux to terminate
your program.

If you have any specific questions, post to this list and we'll try to
clear it up for you.

Mike



-----Original Message-----
From: syslinux-admin at zytor.com [mailto:syslinux-admin at zytor.com] On
Behalf Of René Castberg
Sent: Wednesday, June 05, 2002 11:53 AM
To: syslinux at zytor.com
Subject: [syslinux] Comboot files

First of all Great software,
Do you know how I can get the syslinux to display a help screen and then
return to the menu, or where I can find information on making .cbt
files..

Thanks.
Your help would be much appreciated

Rene