Date   : Sat, 20 Jun 2009 02:25:24 +0100
From   : jumbos.bazzar@... (Mark Haysman)
Subject: One ROM disabling all others on Bootup

>>Is there any magic way of doing this reliably, so that I can keep this one
>>ROM, and Basic as the only active ROMs in the System, without any filing
>>systems claiming their workspace?
>
> Place a JMP <your ROM byte whacking code>@&287.
> It gets called after the ROM bytes are determined,
> and before the first service call goes round (which
> is &FF if the Tube is present, else &01).
>
> Otherwise, service call &01 is your first hookpoint,
> but of course there's no guarantee that no ROM has
> claimed any absolute workspace once you're up.

Thanks John.

I went for Plan B, and after a bit of recoding (as I was initialising things 
in service call &03, now I'm doing it in &01), and forcing the Y register to 
exit with &0E with the trapping active to reclaim any workspace, it's 
working for filing systems above and below the ROM.

Mark.