What is MIDI?
All Apricot PCs supplied with audio capability also include a MIDI / Games Controller Port. MIDI is an acronym for Musical Instrument Digital Interface and is a communications protocol or common language which allows electronic musical instruments to communicate with each other and with computers.

MIDI files contain the equivalent of an electronic musical score. This digital sheet music contains performance information, without any actual samples or sounds. Your computer or electronic instrument contains the patches or sampled sounds that are played from the MIDI score. Computer software such as Audition, Cakewalk, Midisoft, etc. allows computer users to either compose music on screen, or record a performance from an electronic instrument connected to the computer's MIDI interface port.

MIDI computer files differ from other sound formats in that they contain no actual sound samples. Microsoft .WAV files, for example, contain digitised audio samples and as such tend to be much larger than an equivalent MIDI file. It should be remembered though that the same MIDI file played on two different music keyboards could produce different sounding results as reproduction is controlled by the musical instrument's sound generating capabilities.

For more information about the origins and uses of MIDI, try these WWW sites.

http://www.harmony-central.com
http://www.webthumper.com/midi

MIDI Interface (IN, OUT and THRU)
To connect your instrument to a computer or another instrument, it must have a MIDI interface. Externally this appears as up to three round 5-pin port sockets labeled IN,OUT and THRU. These ports control all of the information routing in the MIDI system.

The IN port accepts MIDI data coming "in" to the unit from external sources. This is the data that controls the sound generators of the synthesizer.

The OUT port sends MIDI data "out" to the rest of the MIDI setup. This data results from activities of the synthesizer, such as key presses, etc.

The THRU port also sends data out to the MIDI system, but not in the same manner as the OUT port. The data coming from the THRU port is an exact copy of the data received at the synthesizer's IN port.

How Do I Connect Electronic Musical Instruments?
Lets take a simple example of connecting a MIDI keyboard to a PC. There are two basic types of MIDI music keyboard, a dumb keyboard and a synthesizer. A dumb keyboard (there may be other industry terms to describe this type of keyboard, but we're using "dumb" to highlight the differences with synthesizers) has no internal sound generation circuitry and relies on external equipment (PCs or other keyboards) to produce its sounds. Dumb keyboards generally only have a MIDI OUT port. A synthesizer, on the other hand, is an instrument in its own right, capable of generating its own sounds and normally would have IN, OUT and THRU ports.

On the back of the PC, normally close to all the other audio connection ports, is the MIDI / Games controller port. This port connector is a 15-pin "D" type connector and looks totally different from the round 5-pin sockets found on instruments. To connect the computer to the keyboard, you will need an interface cable which converts the 15-pin "D" type to two 5-pin IN & OUT connectors (there is no need for a THRU connector) and also provides a separate games controller port (where required).

Interface cables are widely available from computer and music stores but there are many different specifications available. Some have games controller ports, some have opto-isolators, some have only MIDI IN ports, the variety can be very confusing. To add to the confusion, some sound card manufacturers have implemented their MIDI interface circuitry in subtly different ways which means that not all cables will work with every keyboard / computer combination. To help with the selection process, Apricot has tested a selection of cables with its computers and can recommend the following suppliers:

When you have a cable, connect the "D" type plug to the back of your PC and, if you have a games controller, connect it to the spare "D" type socket.

The 5-pin MIDI plugs will be marked IN and OUT if you have two, or may have no markings if you are using a dumb keyboard, single plug cable. The IN / OUT markings refer to the direction of data flow to and from the PC or instrument, so connect the IN plug to the OUT socket on the keyboard and the OUT plug to the IN socket on the keyboard.

Making Music With Your PC
Once all the cables have been connected, the instrument won't play through the computer's audio card until an application capable or reading data from the MIDI port has been loaded. In most cases, if you have a synthesizer type keyboard, you will probably want to use the audio reproduction qualities of the instrument rather than the computer. However, if you have a dumb keyboard, the only method of hearing your composition is through the computer's audio hardware, so the software application you are using will probably need to be configured to enable this.

On some PC models, Apricot supplies an application called Audition which will be used as the basis for the remaining text, however much of what follows will be equally applicable to any PC MIDI music package. Audition is a sixteen track notation based sequencer that allows you to record, replay and edit music and musical effects using your PC and a General MIDI, GS Sound Card or sound module.

At Audition's main screen, click on System, select Configuration... and check the Thru box. This option passes the incoming MIDI data out to the designated output device, which by default is the computer's sound card. At this point when the instrument is played, music it produces through the computer's audio circuit and speakers. From this point you can record music, a track at a time, to create your own compositions as required.

If you have a synthesizer type keyboard, you can play your own, or pre-recorded MIDI files from the computer out through your instrument. To do this you must tell the computer which output device to use by performing these steps. From the START button on the task bar, select SETTINGS and CONTROL PANEL. Choose MUTIMEDIA and select the MIDI tab.

Select the external option and click the OK button. When you play a MIDI file now, it will play out through your instrument using its audio reproduction circuitry.

Wave Table Extension
When MIDI files are played by your computer, the sound card hardware synthesizes the audio properties of the instrument, specified in the file, in order to produce music. It's possible to improve the fidelity of this reproduction by using a Wave Table card. Rather than synthesizing instruments, a Wave Table card reproduces instrument sounds from a table of stored samples. This means that a piano or a flute, for example, will sound even better when played by the computer's audio circuit.

Wave table cards are available as options for several audio expansion cards and typically they are designed for use with a specific manufacturer's card. If you have an Apricot MS540 PC, a Wave Table expansion card is available to complement the onboard audio circuit. The card occupies an expansion slot and connects to the onboard audio circuit using a short ribbon cable. No other manufacturer's Wave Table cards may be used.

Once installed, Windows 95 automatically detects the card and provides an additional output device in the MIDI options control panel.

This now gives you the option to select external output to your musical instrument, internal output via the computer's audio synthesizer, or internal output via the Wave Table expansion card. It should be noted that some difference in volume may be noticed when using the Wave Table option, but as this output is directed through the computer's audio amplifier and external speakers, if connected, then a small adjustment to the mixer desk will compensate for this.

Wave Table expansion cards are available through your Apricot supplier by requesting product code XB57690.

Frequently Asked Questions

Q. If I play MIDI files through my computer's audio card, why does it sound different than it does through my keyboard?

Q. I can play MIDI files out to my keyboard, but I can't record from my keyboard to the computer. What's wrong?

Q. What is General MIDI?

Q. What is Roland's GS Format?