Date   : Sun, 07 Nov 1999 16:39:27 +0000 (GMT)
From   : Brian Widdas <brian@...>
Subject: Re: How do you autorun a program from ROM?

On Sun, 7 Nov 1999, Chris Richardson wrote:

> Hi all
> 
> Someone has asked me this:
> 
> > Another tech question: is it possible to have a program on EPROM that
> > runs as soon as you start the BBC (ie, just switch it on without
> > having to enter any keyboard command)?
> 
> I assume he means a BASIC program.

I can see two ways of doing this. You could have the code in ROM pick up
on one of the ROM service codes which informs it that the machine has been
reset, and cause this to execute some code (which copies a BASIC program
to &E00 and runs it, if you want to do BASIC). Or you could start the
machine in the Cassette Filing System (easy on the Master, on the B I
think you'd have to remove DFS/ADFS), and set the machine to autoboot
(again, easy on the Master, on the B you have to set one of the keyboard
links). This causes it to look in Rom Filing System (it's like CFS, to the
extent of having blocks, headers and CRCs, only the data is in ROM instead
of on tape) ROMS for a !BOOT file, which you can then use to CHAIN a BASIC
program from RFS.

I can probably dig out more info on most, if not all, of the above. I
might even still have an RFS ROM image creator I wrote lying around
somewhere.

Brian
-- 
Save a life - give blood. 0345 711 711
http://www.blooddonor.org.uk/