Date   : Mon, 26 May 2003 19:30:52 +0100
From   : "Martin Rigby" <martin@...>
Subject: Re: B+ shadow RAM query

According to David Atherton's Master OS Guide, the OSBYTE command you are
referring to appears to be &71 (113) :-

" Select screen for video display"

The blurb states that "calling OSBYTE &71 can flick instantly between the
two" (referring to main and shadow RAM)

Called with X=1 selects main memory (immediately)
X=2 selects shadow memory (immediately)

Does this help?

Martin

-----Original Message-----
From: Majordomo List Manager [mailto:majordomo@...]On Behalf Of
Mike Tomlinson
Sent: 26 May 2003 18:58
To: bbc-micro@...
Subject: Re: [BBC-Micro] B+ shadow RAM query


In article <Pine.LNX.4.44.0305261636520.2528-100000@...
org>, jim <24601@...> writes

>It would change, though the OS clears the screen if you go via *SHADOW.
>I'm sure I tried it back in the day (I tried most things).

There's a *FX command that changes the paged in RAM without clearing the
screen, but I can't remember what it is.  It's used on the Master
Compact demo disks to produce smooth animation by flipping between main
and shadow memory.

>Sounds good. Never encountered a shadow board for a model B, though.

My B has a Watford shadow RAM board which works well, and I think it
implements all the * and *FX commands on the B+.