13.3
MIDI
It's hard to imagine today - but before 1983, there was no consistent protocol that could
have been used to combine synthesizers from different manufacturers. Dave Smith
(Sequential Circuits), in collaboration with Ikutaro Kakehashi (Roland Corporation), created
a hardware interface and associated protocol that was technically appropriate, easy to
implement, and easy to control. I remember very well the magic of connecting a Roland
JX-3P and a Yamaha DX-9 with this somehow old-fashioned 5-pin cable. Playing the sound
engines from a DX-9 and the JX-3P from one keyboard at the same time was incredibly
exciting. Five-pin DIN cables had been finally banned from domestic living rooms a few
years earlier, and the RCA cable had long since lost its superiority in the hi-fi world, as this
strange plug was dug up again in modern synthesizers. That was one of the thoughts that
then turned into this MIDI interface. Not only was the MIDI interface new - for most users,
the MIDI interface was the very first digital data connection they had ever experienced. At
the time nobody had a computer and therefore had no experience with data processing of
any kind. But this MIDI interface revolutionized the technical possibilities enormously and
started a deserved triumph in the music world. A few months later, it was no longer possible
to market electronic musical instruments without this interface.
MIDI has two major advantages over the much faster and more universal USB interface - it
can actively send data, while a USB device must always wait until its data is polled by the
host computer. Galvanic isolation between the connected devices is accordingly MIDI
standard compulsory program. As a result, no hiccup loop can form across the MIDI
interface, and noise that may be inevitable on the bulk of a microprocessor supply may not
be able to propagate to the next device. Therefore, the MIDI interface still has something to
offer today, which many miss USB-based solutions. Only a few manufacturers provide a
galvanic isolation of the USB interface.
What does MIDI actually do? Basically it is a primitive language to exchange musical
commands as effectively as possible between multiple musical instruments. The most
common command, for example, is the note command. A note command usually contains
information about the pitch being played and the velocity used for that tone. So this MIDI
event is sent when you press a key. If you release the button, another command is sent.
This can be another note command with the velocity value 0, or a so-called Note Off
command.
Of course that's not all that MIDI can do. If you trigger the pressure dynamics (aftertouch),
this will be sent as well as the movement of the pitch bender or the regulation of the
modulation wheel. A common tempo base can also be created via MIDI. So-called MIDI
real-time messages transmit a 96th clock, start, stop and continue commands to run
several sequencers and drum machines at the same speed.
von
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Summary of Contents for DELTA CEP A
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