From: K3H (ALBERT SCHOFIELD.)
Subject: TAPE TO DISC ON THE BBC 'B'
Some cassette based games can only be
made to work on disc by loading part
of the game via Sideways Ram. COMBAT
LYNX is one such game.
This game is in three parts, COMBAT,
LYNX and LYNX1. Part one is a basic
program and *RUNs the second part. The
second part is the loader for the
third part. It is locked but works
just as well when unlocked. The third
part is also locked but will not work
when unlocked. It is also a very long
file (&7C00). The load address is
&400. It therefore needs downloading
but because of its length, I have found
this impossible to do. Therefore it
has to be loaded from Sideways Ram and
locked in the Rom Filing system.
COMBAT LYNX can of course be
transferred to disc using SNAPSHOT. But
this causes corruption at the bottom
of the screen and also the flashing
cursor is present. So for a perfect
load SWR loading must be used for the
last part.
So load in the first part. Delete
line 20 and add the following lines:-
20 *KEY10 CLS|M*LOAD LYNX|M*ROM|M
*OPT1,2|MCALL&2C00|M
30 ?&FF30=0:*LOAD LYNX3R 8000
40 ?&FF31=0:*LOAD LYNX2R 8000
50 ?&FF32=0:*LOAD LYNX1R 8000
60 CALL!-4
Save this to disc as COMBAT.
This file works with the Watford
Rom/Ram board. Otherwise you may have
to alter lines 30, 40 and 50 to suit
your SWR.
Load the second part from cassette
with an unlocking utility using
*LOAD""2C00 and save it to disc using
*SAVE LYNX 2C00+2C00.
The third part, due to its long
length, will have to be transferred to
disc using the one block at a time. The
method which I described in an earlier
article. Also because the file is
locked, the file that does the
transferring will have to be combined
with an unlocking utility.
The file can now be saved into three
ROM images and also locked.
To do this I use the excellent ROM
Image Generator by Mark Lock from the
november 1987 issue of BEEBUG
magazine. This allows you to lock the
files and also continue from one rom
image to another with long files.
Save the rom images as LYNX1R, LYNX2R
and LYNX3R and it is essential that
the long file itself is saved as
LYNX1. It is also essential that the
rom images are loaded in the correct
sequence. The first file (COMBAT) does
this.
Chaining COMBAT will now load the rom
images and *RUN the game. LYNX1 will
now load from the RFS in about twenty
seconds and give a perfect display.
From: 15A (Steven Flintham)
Subject: Custom Master MOS's
I was interested to see Jeremy
Stanton's message about this in the
last issue as I'd been thinking about
something along these lines myself.
Given a socketed MOS and an EPROM
blower capable of blowing a
sufficiently large EPROM (assuming
they exist) it should be possible but
I don't actually know. I've assumed
it's possible for the rest of this
message.
Replacing a complete ROM with another
one would probably be relatively easy
although I think replacing the
Terminal and View ROMs would be
difficult. The Master Reference Manual
Part One, page F.2-2 refers to ROM 15
as the MOS, 'incorporating... the
Terminal emulation software' and
(although I can't find a more
definitive reference) I seem to
remember an old Micro User claiming
that the MOS's flood fill code is
located somewhere in the View ROM.
Anything more involved might be
difficult, especially modifications to
the MOS itself, but I suppose someone
with sufficient talent and patience
could do it. One possibility might be
to modify the MOS so that the RTC
supports dates in the next century
correctly. I don't really know but I
suspect that if it was acceptable to
no longer support years in this
century it would be possible to just
patch the code rather than rewrite it.
This is probably not feasible or
worth the effort, since the date isn't
used very much by either the MOS or
any other software.
From D6G
Sprow
1Mbit ROM
=========
Carving the waste out of the Master's
MOS was the subject of J Stanton's
letter last issue.I did think of doing
this some time back as I have some
blank 1Mbit (128Kbyte) roms and a
suitable programmer.
The reason why I didn't was for the
following reason:
The BBC OS1.20 is 16k and,compared with
the Master is very simplisitic,it has
none of the advanced graphics (eg.
L/R/U/D window scrolling no ellipse
fills no parallelograms etc...) nor
all of the text for *STATUS and the
extar text for the new *HELP MOS nor
all of the new commands.I don't think
even Acorn could squash all these new
features into just 16k.
So how did they manage? - given that
16k MOS core
16k VIEW
16k DFS
16k ADFS
16k EDIT
16k BASIC
16k TERMINAL
16k SHEET
====
128k (1Mbit)
To get around this space problem Acorn
put all the infrequently used stuff in
the other ROMs.For example TERMINAL is
fairly simple and doesn't occupy the
full 16k,so the spare space is used
to hold the default character set (to
prove this CHAIN my simple program on
this disk: SCRNROM which dumps to
screen the TERMINAL image.You'll see
the character set at the end.
Similarly,the *SRLOAD/SAVE commands
appear at the very end of the DFS rom.
Hence,removing one rom would cause the
MOS to fail.Obvious exceptions to this
are (for example) BASIC IV which we
know takes the entire 16k.It would be
'safe' to remove this,perhaps VIEW too.
Contact me at the usual address (see
separate note)
8BS mail me on D6G
Robert Sprowson.
From D6G
Sprow
Mike Mallet (D6K) wanted to know if
there was a relevant link in the Master
to make it colour composite video.
No such luck.The relevant bit of info
is as follows,and can be found along
with over 200 other hints on BBC147
from the PD library.Send Chris 50p
and a disk with stamp.
The reason why Acorn didn't make all
composite video colour is because
they expected most people to use the
RGB with a Cub monitor.Making the
colour modification degrades the RGB
output - looks like you can't have the
best of both worlds!
The article reads:
170. Composite video colour for Master
÷÷÷÷÷÷÷÷÷÷÷÷÷÷÷÷÷÷÷÷÷÷÷÷÷÷÷÷÷÷÷÷÷÷÷÷÷÷
To get a colour signal from the CV
output socket, I hear that you can
solder a 470pF ceramic capacitor
between the emitter (right leg) of
transistor Q12 and the base (centre
leg) of Q13. These are located between
the CV and RGB sockets, and although it
is a slightly delicate soldering job,
it is nowhere near as tricky as the
equivalent modification on an early
BBC B.
Contact me at the usual address (see
separate note)
8BS mail me on D6G
Robert Sprowson.
From: D8J (John Robson)
Subject: Sticky Keys (again)
I have had the same trouble with
keys on the keyboard sticking or
not working from the Electron to
the BBC Master 128.
Like other users I also use WD 40
but with a slight difference:-
squirt a little WD 40 around the
top of the key spindle (take the
key pad off first), work this well
into the actual key by pressing it
up and down and from side to side.
After this it has two choices - it
works or it not works! Get some
surgical spirit and a child's school
paint brush, dip it in and brush it
around the top of the spindle so it
runs to the inside of the switch.
This thins the WD 40 down a little.
In the morning turn the machine up-
side down, key pad still off, and let
the fluid run out by pressing the key
about once every hour a few times
throughout the day. After about 6
hours switch on and it should be
working again 100%.
If not then it will have to be
unsoldered using a 25 watt soldering
iron and a solder sucker, and a new
switch put in. This is not hard to do,
if you have a spare machine for
spares.
--------------------