You've got a problem with your micro and you just can't sort
it out on your own? Then write to MIKE COOK. If he can't help
then probably no one can . .
Not making the most of my dual cassette system
I have found the dual cassette system described in the Body
Building Course in the August, 1983 issue of The Micro User very
useful and effective.
However, not being familiar with the use of assembly language
or opening and closing files, I cannot use the device as I would
like. Can you help please?
I have used some machine code programs, in particular Psion's
VuCalc, and this prevents use of the dual cassette system, presumably
because the patch is overwritten. Where could the patch be relocated
and how?
I would like to be able to read files, search for particular
sets of information, alter if necessary and then either print
out or save again using a database.
How can I alter the database program to do this?
My understanding is that tape based databases read ALL of the
data in, then allow editing before printing or saving ALL of the
data again. - EA. Terwaite, Gateshead.
• To move the machine code patch for the dual cassette board,
change line 80 to the required address.
Without knowing what memory locations are used by the commercial
software it is impossible to say what value to try.
However experiment with some values. You might like to try &C00,
&00, & 100 or &800.
Your understanding of conventional tape database programs is
correct, but with a dual tape system you can have two files open
at the same time, one for input and one for output.
This means you can read a section into the computer,
process it and write it again before getting the next section.
This is like transferring the water in two 60 gallon tanks with
a bucket. The computer is the bucket, only holding a portion of
the water at any time.
Bar code software
ARE you planning to publish all the major software printed in
The Micro User on Micronet?
If not, why not publish the programs in bar code format, with
another program so that those of us with light pens can convert
them to read bar codes. This would save much tedious keying in.
- P. Watkins-Field, Prestel Mailbox 919991169.
• You cannot convert the light pen into a bar code reader as
this would need a light source and an accurate means of alignment,
possibly involving fibre optics. It would be more economical to
start from scratch.
As to bar code listings, these would take up far more space
than a normal listing, thus reducing the number of programs printed
in each issue.
Also the page would be of little use to a reader who was not
seated by his computer. A full listing is often easier to study
than just looking at a small portion on the screen.
Anyway if you don't like typing them in then The Micro User
cassette is a cheap alternative.
We have thought about your proposal but have come to the conclusion
that attractive as it superficially sounds, it would not be worthwhile.
Nasty video colour
I AM making animated displays to be included in a video film
teaching aspects of mental handicap and need a reasonable means
of getting my computer output onto video tape with colour.
I was delighted when I read your reply in the August issue of
The Micro User entitled "Colour Clue", explaining how
to make the black and white video output colour.
However inserting the capacitor wasn't as easy as it sounded.
Is this something you've actually done yourself, or just looked
at on a wiring diagram?
The end of resistor R123 which one needs to solder to is buried
in the computer circuit board and the legs of capacitor Q9 are
very hard to reach.
On examining the circuit diagram issued with the Advanced User
Guide, connecting the exposed loop of R133 to the emitter of Q7
seems to be the same, and I was actually able to do this.
The capacitor used is a 56. Not Picofarad, it had something
like MSI% 56 written on it. The actual maker's mark got rubbed
off while putting it in, but it is definitely a 56. I did try
a 47 Picofarad as these were the options I had locally.
Now to my current problem. Although with this attention I can
now get colour on my video output it is weak, although the picture
is crisp.
If I turn the colour knob on my TV up the stripey effect on
the edge of the picture increases to an unacceptable level.
Have I made the connections correctly? Is my present capacitor
OK?
Thirdly, is there any way I can get good enough colour on the
video output to make use of on film? - John W. Drake-Law, Newton
Abbot, Devon.
• Try using a larger value capacitor, Acorn recommend a 400pF.
The value is not critical, but as you have discovered the PAL
encoded signal is not very good.
To incorporate the BBC Micro with video signals you will have
to lock the two sources of video together. This is tricky and
expensive.
However if you want further details of the units available to
do this contact Colin Malone at BBC Enterprises, Langham Place,
London.
Chip shops run dry
WHAT'S happening to Mr Chippy? Has there been a famine? Have
the chips dried up?
We are requesting help out of desperation. Having upgraded our
BBC Micro, we are unable to obtain the 88LS120, essential for
the RS423 interface.
We are currently sharing the only available chip with a friend
who has an older BBC Micro as the new models have the chip soldered
in.
There is every possibility of the legs weakening or even fracturing
— the chip that is, not our friend.
Any advice relating to the availability or alternative appreciated.
- Brian Hording, Prestel Mailbox 068952023.
• Yes, there is a worldwide shortage of chips. Even Acorn is
feeling the pinch and is bringing back the Model A to make its
supplies of memory devices go further.
We have also heard that the chip you are after is in very short
supply. All we can suggest is that you keep ringing up IC stockists
until you find one who has taken a delivery.
If it is any consolation, in the past a chip shortage has always
been followed by a price drop when they become available again.
However, according to our sources this is the worst chip shortage
ever. Sorry — just keep plugging away.
Stop your motor fast
REFERENCE Mike Cook's article about the Block? message when
reading a program from cassette in the September 1983 issue of
The Micro User, and the Micromail letter in the following issue.
Can you suggest any modification that can be done to my cassette
recorder, a Ferguson model 3T07 with remote motor control, to
stop the motor quicker? - R. Eastland, Portsmouth.
• The cassette recorder probably contains a smoothing capacitor
which is keeping the motor running after the remote control has
been switched off. You could try disconnecting this.
A better solution would be to arrange for the remote control
to not only turn off the power to the motor but also to short
out its windings.
In this way any inertial energy would be converted back into
electricity and be used to drive the motor in the opposite direction.
The net result of this is that it would act as a power assisted
brake. This is a similar system to that used in electric trains.
If you are not sure how to make the modifications it is best
to stick to the software patch.
Which wire goes where?
I received your Body Building Packs 1, 2 and 6 and would be
grateful if you could answer the following queries:
1. The diagram in the October issue of The Micro User shows
the red/black/screen connections at the D-plug and the locations
of pins 1, 2 and 3 on the light sensor, but gives no hints as
to which wire goes to which number pin. Any clues?
2. On assembling the user port bit and inserting it, the LED
does not light and the +5v pin is at +1v. Any thoughts? - FA.
Richey, Salisbury, Wiltshire.
• The pins on the light sensor number from top to bottom 1,2,3.
Your problem with the user port sounds like the cable being wrong.
Check this carefully.
Buzz off
I have bought every issue of your excellent magazine, and have
found the Micromail section particularly helpful, so perhaps you
can now help me.
I have an annoying buzz coming from my BBC Micro. How can I
stop it?
How can I get more than 32k on my micro, and what is the 1MHz
bus for? - C.D. Arthurs, Prestel Mailbox 494713773.
• If you have an issue two or three board, the buzz can be reduced
by fitting a 10k resistor from the analogue input pin on the 1MHz
port to earth. It can be soldered on the underside of the printed
circuit board if you take it out.
On issue four boards and later this should have already been
done, in which case you can turn down the volume by using the
preset volume control at the bottom left hand corner of the board.
To get more than 32k, buy an Aries board from Cambridge Consultants.
The 1MHz bus is to allow extra input/output devices and paged
memory to be attached to the computer.
Extra memory added in this way cannot be used for storing basic
programs but can be used for storing data, but you have to write
the routines to handle this.
Interlacing troubles
In the March and April 1983 issues of The Micro User there appeared
articles on monitors. The March article included a statement that
interlacing should be turned off when a monitor is used and referred
to the User Guide.
Page 435 of the User Guide includes OBSBYTE call with A = &90
and the note on this refers to interlaced displays. I cannot understand
how you turn off the interlacing.
As I now have a monitor would you please be good enough to explain
in simple terms how this should be done. - F.H. Molyneux, Cleethorpes.
• Interlacing cannot be turned off in Mode 7. If the phosphors
on the TV tube are of short persistance, interlacing can cause
an annoying flicker.
To turn it off, type *TV 0,1, then type Mode 0 (or any other
mode apart from Mode 7). However I doubt that you will notice
the difference.
Atom plus Model B?
I own a BBC Model B with View, disc drives and an FX-80 printer.
Like many BBC owners I still possess my Acorn Atom.
In my case it is fully expanded with word processor, etc, and
70k of RAM, being fitted with the DUO system of two paged 32k
RAM plus 6k video RAM.
Is it possible to link the Atom to the BBC Micro to supplement
the BBC's pathetic memory with the Atom's massive memory, as a
second 6502 processor?
Or is it possible to link them, via Econet say, to enable the
Atom to make use of the BBC's disc drive?
The Atom has never been provided with a disc drive interface.
All Acorn ever provided was an extremely extortionist complete
package of interface plus drive. It is gathering dust for lack
of discs.
I believe Econet was first produced for use with the Atom. There
must be many readers in my situation since the natural action
was to upgrade from the Atom to the BBC when the former became
obsolete. — D. Rogerson, Upminster, Essex.
• Unfortunately the Atom is not designed to be used as a second
processor. In theory it is possible to do this but you will end
up using the Atom's Basic via your BBC keyboard.
In practice the information required to use the Tube is not
being released by Acorn so you are faced with a voyage of discovery
trying to unravel its mysteries.
If you have the knowledge to do that we think your efforts would
be better suited elsewhere, like writing for The Micro User! You
will make a lot more money than you will save by linking these
two.
No Apple disc link
I have a BBC Model B fitted with disc drive interface and have
easy and extended access to an Apple disc drive (Disc II with
DOS 3.3).
I understand that the two cannot be directly connected, and
that some further interface will have to be obtained or constructed.
I would be grateful for any assistance you could give in this
matter. - Walter F.F. Curtis, Norwich.
• Sorry, but they are really not compatible. You could design
an interface if you had the time and the skill but it would end
up costing you more than buying two disc drives.
