Date   : Tue, 28 Jan 2014 08:57:35 +0000
From   : public@... (Daniel Beardsmore)
Subject: Torch_Graduate

>  From: J.G.Harston <jgh@...>
>  To: bbc-micro@...
>  Subject: Re: [BBC-Micro] Torch Graduate
>  Sent: 28 Jan '14 03:27
>  
>  There's a clever trick where a 1MHz peripheral can take control of the
>  Beeb without there being any code in the Beeb.
>  
>  On RESET, after doing most of the startup setup, before looking for any
>  ROMs, the MOS briefly enables interrupts. If an interupt was pending
>  because IRQ has been held low since RESET, then a call is made to
>  (&FDFE).

Ah ... that must be how this thing works:

http://telcontar.net/Misc/random/SRAM-drive.php

I'll need to read up on FRED and JIM again later when I'm back at home. 
I was going to read the Beeb wiki, but Google is stubbornly insisting that
no such thing exists, and that FRED and JIM don't really exist. I'll just
read the Advanced User Guide later instead.