Apple Logic (1.1) - Manual (Page 97)

Chapter B Audio and MIDI in Mac OS X 97
Core MIDI
MIDI data is handled by the Core MIDI system of Mac OS X. Compatible MIDI interfaces
for connecting a keyboard, MIDI fader unit or external sound generators are recognized
and activated automatically.
The MIDI Page of AMS
The AMS application offers a MIDI page that allows you to see all installed MIDI
interfaces, and make connections between them, if necessary.
Please note, however, that you don’t need to change any settings in this page if you
want to use the MIDI interface(s) with Logic. All MIDI parameters and connection
options can be accessed directly in Logic’s Environment.
A Brief Guide to Connecting MIDI Hardware
If you use a simple master keyboard—without an integrated sound generator or fancy
master keyboard functions—you’ll only need one cable to connect the master
keyboard’s MIDI Out with the MIDI In of the MIDI interface.
If the keyboard can generate its own sounds, connect the computer’s MIDI Out to the
keyboard’s MIDI In. If your computer (or the MIDI device) offers more than one MIDI
output, connect any other tone generators to these.
If the computer only has one MIDI output, you need to connect the second tone
generator’s MIDI In to the keyboard’s MIDI Thru port. A third device can be connected
to the second’s MIDI Thru, and so on. The MIDI Thru port always delivers a copy of the
signals coming into the device’s MIDI In. It is preferable, however, to use a direct
connection from a computer’s MIDI Out to a device, rather than chaining too many
devices, one after the other. This is because timing problems may occur in the chain, if
numerous MIDI commands are sent in a short time period. This is due to the slight
delays introduced by each MIDI In to MIDI Thru transaction.
If your computer offers several MIDI inputs, you can connect the MIDI outputs of other
MIDI expanders to it.
MIDI Local Off
If your keyboard has an internal sound source, it is important that you stop the
keyboard from generating sounds directly from its own keyboard. If you buy a new
keyboard that is to be used without a sequencer, and connect it to an amplifier, you
would expect the device to make a sound when you press its keys—in other words, the
keyboard is directly connected to the sound generator.