Date   : Wed, 09 Feb 2000 01:23:26 +0000
From   : Mike Tomlinson <mike@...>
Subject: Re: More tiny problems...

In article <E12HZXz-0005sc-00.2000-02-06-21-48-47@...>,
Barrie Ellis <dobre@...> writes

>Hoping someone can help...I've just been given a BBC Master which switches
>on in *TAPE mode, meaning I have to type *DISK to get the disk filing system
>going. Is there a simple fix to get it immediately in disk mode?

*configure file 9

>Will the battery dying stop the machine running normally in the future?

yes.  It'll make the machine a pain to use as you will need to
reconfigure it each time you turn it on. Get a new battery pack or make
your own.

Very early Masters had a design fault in the battery charging circuit,
so when the battery went flat the machine attempted to charge it.  The
design was changed by Acorn when a couple of Masters caught fire.

>Also - weren't BBC Master's supposed to have 128K? So why, when I type PRINT
>HIMEM-TOP, do I get the same value of memory space as a 32K BBC B?

Someone else has already given the answer, but try typing *SHADOW and
then change mode (or add 128 to the mode number) - this moves the screen
into shadow memory so you get the full amount of memory from PAGE
(&1900) to HIMEM (&7FFF) available to BASIC programs, unlike the model
B.

32k base memory
32k shadow memory
64k arranged as 4 off 16k sideways RAM banks

The below is a list of the ROMs in the Master, to the best of my
recollection.  I can't remember which slots are taken by the sideways
RAM banks.  Anyone fill in the gaps?

F Terminal
E BASIC
D ADFS?
C View
B ?
A ?
9 DFS
8 Empty ROM socket (middle of the 3 available)
7 ? (SW RAM?)
6 ? (SW RAM?)
5 ? (SW RAM?)
4 ? (SW RAM?)
3 ? 
2 ?
1 ?
0 ?

Note that there are 3 free ROM sockets available on the Master's circuit
board.  The middle of the 3 is slot 8.  Using the other two disables
sideways RAM.

IIRC again, you need a ROM board to use slots 0-3.

>Lastly - why is the colour TV signal so bad from BBC Micro's?

it always has been.  I used to find it amusing that my old Spectrum
produced a much better picture on a TV than my Beeb, even though both
use the same Astec modulator.

>(or does anyone know where there is a
>cheap supply of colour monitors)?

The Microvitec Cub 14" colour monitors were going for about 7 quid at
the annual Norbreck Castle radio rally in Blackpool last year.   That
was seen working.  Even the higher resolution models were the same
price, and those give a very good picture when used with a Beeb.

The rally is usually held sometime around the end of March.

-- 
Mike Tomlinson
mike@...