Date   : Mon, 29 Aug 2005 18:34:19 +0100
From   : "Ian Wolstenholme" <BBCMailingList@...>
Subject: Acorn OS 160K ??

I was having a root around inside DFS 2.26 following on from the
messages earlier and I found some text at the very end of the ROM
in the last 100 bytes or so as follows:

Acorn OS 64K 80K 112K 128K 144K 160K

and it got me thinking about whether there were, or intended to be,
versions of the BBC B+ with different amounts of RAM than the usual
64K or the rather rare 128K.

The text is used in the start-up message and you can trick it into printing
the start-up message using the following procedure:

1.  Attach 6502 second processor
2. Issue *FX 142, (ROM number of DFS 2.26)
3. Ignore "This is not a language" error
4. *GO BF01

When I do this I get "Acorn OS 160K" followed by the familiar VDU 7
bleep.  If I press BREAK and do *GO BF01 again I just get "Acorn OS"
as you would normally after pressing BREAK.

The DFS 2.26 ROM must have some way of detecting how much RAM or
sideways RAM is installed.

Has anybody tried this before or got a Beeb to come up with a memory
message other than 64K or 128K?

Best wishes,


Ian