Your Commodore - Commodore Is Awesome

U
page n at the sight of an acronym or
unless l you've been holidaying on Mars
for the last three years, you must have
heard
e
of MIDI. If you have bravely
tackled s articles about MIDI and are
still s feeling left out in the cold you may
be y forgiven for thinking that a
conspiracy o is afoot to keep MIDI and
its
u
secrets out of the hands of the
computer-owning
a
public.
The fact is, there has really been no
down-to-earth u
source of information
about t MID! and rather than spend (or
waste?) o a couple of pages explaining
what m it is, most magazines have
plunged a straight in with MIDI
equipment
t
reviews leaving many
readers stranded at the start. Let's try
to
i
put that right. Explanations Initl;
the c reviews will follow in Part Two.
a
What l is MIDI?
l
MIDI y is an acronym for Musical
Instrument
t
Digital Interface. It was
designed and developed by major
musical u instrument manufacturers
such r as Sequential. Roland and
Yamaha n to overcome the problem of
linking t together instruments produced
by h different companies. Each
manufacturer
e
has its own individual
instrument design and prior to MIDI
the chances of mix-and-matching
without expensive interface equipment
were remote. MIDI laid down rules by
which musical information could be
standardised in digital form and
transmitted and received thorugh DIN
sockets. Instruments have at least two
such sockets: MIDI IN and MIDI
OUT. Many also have a MIDI THRU
socket which passes on information
received via MIDI IN. This enables
you to daisy chain together several
pieces of equipment.
MUSIC
Midi Music
and You
Ian Waugh brings you MIDI without tears and explains
how Commodore owners are the luckiest people in the
musical world.
In its simplest form MIDI works
like this: if you connect the MIDI OUT
of keyboard one to the MIDI IN of
keyboard two, the first keyboard will
transmit musical data down the cable
and you will be able to splay' the
second keyboard from the first.
The first keyboard is known as the
Master and you could connect other
keyboards to the system by using
MIDI THRU sockets. MIDI really
comes into its own, though. when
under computer control. As the signals
are digital, what better way to control
them than with a computer.
Signals
The nature of MIDI signals sometimes
causes confusion. It is important to
realise that they are not audio signals
but digitals signals, the zeros and ones
of computer language. They control
the pitch and alter the instrument's
performance controls such as pitchbend,
modulation (for vibrato),
sustain, volume, velocity, sensitivity
(the hard:r you hit a key, the louder
the note) after touch (pressing a key
down further after playing it to
produce wow or delayed vibrato, etc.)
and patch changes.
Not all MIDI instruments have all
these facilities and it's important to
realise that you can't produce after
touch for example on a keyboard
which does not have it built-in. Many
drum machines and effects units such
as echo and reverb now have MID! so
you can put these under computer
control, too.
It wouldn't be terribly useful if you
coud only control one instrument at a
time - a sequencer could do that - so
the MIDI specification permits up to
16 different messages to be sent at
once. Each message, carrying its own
YOUR COMMODORE november 1986:81
pitch and modulation information
etc., is sent on a different channel, and
the receiving instruments can be 'tuned
in' to the channel you want them to
respond to. Actually. MIDI data is
transmitted serially so although
information on all channels is not
technically sent together it's fast
enough to seem like it.
When information is transmitted, a
code is sent to identify which channel
the message is meant for. Most
instruments allow you to set the
channel they will broadcast and
receive on and they will ignore data
intended for other channels. Under
computer control you will normally
allocate a different channel to each
musical part e.g. channel one for the
bass, channel two for strings, channel
three for lead synth. etc. The software
will then send the parts to the right
instruments.
In Use
It is not essential to know how MIDI
works in order to use it and although
the principles are quite simple the
implementation can appear quite
daunting. For example, it is necessary
to literally spell out every single
operation you want an instrument to
perform - much as you must spell out
everthing to a computer. There's a
MIDI code for turning a note on and
one for turning it off, Some operations
such as after touch require large
amounts of information which can
quickly use up the computer's
memory. Some software gives you the
option of ignoring such memoryhungry
features.
Normally the software will take
care of all these functions,for you but
some programs, especially editing
packages, let you get right down to