          MIDI for the Computerphile                             Page 1


                        A MIDI Primer for Computerphiles

               In the course of pursuing my dual interests in music and

          computers, I've noticed one thing:  though "crossover" in these

          two fields is certainly evident in hardware and software, most

          computer folk seem to know little about what those weird musician

          types are doing with their digital machines, and musicians, well,

          many musicians still think a byte is something you go out for

          after playing a set.  Hopefully, this report will be of some use

          to computer people who would like to know something about the

          computer revolution which has swept the music industry, but don't

          know where to start.  Obviously, this is a very large topic, and

          I can only present the broadest outlines here.  If there is

          sufficient interest, more detailed reports will follow.

                     A Basic Definition and a Little History

               MIDI (Musical Instrument Digital Interface) is a

          communications protocol developed jointly by American and

          Japanese manufacturers of electronic musical instruments.  It is

          a defined standard administered by an independent association,

          the International Midi Association, and, at least theoretically,

          assures compatibility among equipment produced by different

          manufacturers.  In practice, the ideal of total compatibility is

          not always achieved, but at least "MIDI standard" has a little

          more meaning than "RS232 standard interface".

               Now for a little history. MIDI is a fairly recent

          innovation; the standard was first proposed in 1981, when,

          fortunately, it was realized that unless someone did something,

          chaos would prevail in the musical instrument industry (with, of

          course, the resultant loss of sales.  Never forget that MIDI was

          spawned by manufacturers, not by users.  More on this later.)

               Over the past 15 or 20 years, many electronic instruments

          have been introduced.  Keyboard synthesizers are examples that

          are probably familiar to most people.  These machines were analog

          devices -- the pitch of the sound they produced was determined by

          a linear-scaled control voltage generated by the keyboard.  With

          the advent of microprocessors, it became feasible to produce

          digitally controlled instruments, eliminating the inherent

          instability and inaccuracy of the analog control approach.

          Please note, that the terms digital and analog are used here only

          to describe the method of control; they have a totally different

          meaning when applied to the technique used to generate the sound.

          That will be discussed in the section on Hardware.  Anyway, what

          is important is that instead of keyboards that produced varying

          voltages, you now have keyboards that produce discrete codes,

          just like a computer keyboard.

               Now I must digress for a moment, and present a short

          discussion on the elements of tonal music.  Tonal music (as

          distinguished from atonal music, i.e. noise) can be described as

          constituting three determinant parameters:

                    1 - Notes (comprised of pitch and harmonic data)

                    2 - Volume (how loud or soft the sounded note is)

                    3 - Duration (how long the note is sounded)

               A digitally-encoded keyboard is capable of generating, as a

          discrete quantity, only one of the 3 parameters.  Notes are

          determined by which key is pressed.  However, duration can be

          determined by measuring how long the key is pressed against a

          known time base.  Volume is a little tougher; you can measure the

          pressure with which the key is hit, but that will necessarily

          require analog measurement.  However, if you measure the time

          between the moment the key begins to be depressed and the moment

          it is fully depressed, you will know how fast the key is

          travelling, which gives a good indication of how hard it was

          struck.  This measurement, (beginning of key travel - end of key

          travel/time) is called "velocity" and provides the third

          parameter.  (Some MIDI instruments use analog pressure

          measurements to generate velocity data).

               If these three parameters were recorded in real-time, and

          then transmitted to an instrument, it would be possible to

          reproduce the original performance exactly as the musician played

          it.  This technique offers a major advantage over analog

          recording technology:  there is none of the degradation of sound

          which is inherent in any analog recording process.  The first

          devices which attempted to store and reproduce these parameters

          are familiar to everyone:  the old-fashioned player piano

          captured key presses in real-time and stored them on paper piano

          rolls for later retrieval.  The evolution of electronic

          instruments resulted in various schemes to electronically store

          these parameters.  However, the early attempts at "sequencing"

          (the process of coding, storing and retrieving note, volume and

          duration data) were individually developed by each manufacturer

          -- compatibility between different brands of instruments was rare

          (nonexistent).


               The MIDI standard was originally proposed to provide a

          single standard to be used by all instrument manufacturers, so

          that varied and different instruments could function together.

          However, as will be shown later, MIDI has evolved considerably

          beyond a basic note definition "language".

                             A Little Technical Data

               I won't reproduce the full standard here because it is

          readily available from a variety of sources and is not necessary

          for understanding the basic principles and applications of MIDI.

          MIDI is a synchronous digital protocol.  Data is sent in 8-bit

          words at 31.2K baud using a current loop.  Why yet another

          format, when good ole' RS232 is sitting there on just about every

          computer in existence?  The official Party Line is:  RS232, with

          its top speed of 19.2K is too slow to handle all the note data.

          Current loop is necessary to suppress interference that would

          result from the long cable runs.  Could it be an excuse to sell

          more hardware? Hmmmmmm.  Anyway, back to facts.  MIDI protocol

          consists of control and data words which may be from 1 to 3 bytes

          long, or, in certain situations, longer.  MIDI defines the three

          parameters from the previous section as follows:

                    NOTES:  128 notes are defined, from 0 to 127.  Notes

                    follow the standard even-tempered chromatic scale.

                    Notes are NOT defined as specific frequencies,

                    permitting performers to tune their instruments as

                    required.

                    VOLUME:  The primary means of specifying volume is

                    velocity (see previous discussion).  Velocity is

                    quantized per note in discrete steps from 0 (softest)

                    to 127 (loudest).  There are also other parameters

                    which control relative volume of the entire instrument.

                    DURATION:  MIDI handles duration of notes with two

                    parameters:  NOTE ON and NOTE OFF.  NOTE ON is

                    generated when the key is pressed, NOTE OFF is

                    generated when the key is released.  These two commands

                    are sent independently of each other; if a NOTE ON is

                    issued and a corresponding NOTE OFF is not sent

                    (because of data errors, mechanical failures, or poor

                    programming) the note will sound forever (or until the

                    instrument is turned off).  This presents occasional

                    problems, particularly in live performance, because, as

                    in any communications protocol, data errors do

                    sometimes happen.  MIDI does provide an "All Notes Off"

                    command.

               As stated before, duration must be measured against a known

          time standard.  MIDI provides a MIDI clock signal, which is sent

          as a specifically designated data byte.  MIDI divides each

          musical beat into 128 MIDI clocks.  MIDI also defines the

          following parameters:

                    PROGRAM CHANGE:  This parameter selects different

                    "patches" or sounds in the musical instrument.  The

                    programs are numbered 0-127.  Note that the patches

                    themselves are not defined by the MIDI standard.

                    Program #32 might be a violin on one synthesizer and

                    barking dogs on another.

                    CHANNEL:  MIDI provides for 16 different channels.

                    Most MIDI commands and data can be specific to a single

                    channel, i.e. instrument, or can be global.

                    PITCH BEND:  As the name implies, the pitch of the note

                    can be "bent" up or down in real time (remember Jimi

                    Hendrix?).

                    MODULATION:  This is a control parameter that usually

                    effects the vibrato sound of the note, though some

                    instruments can be programmed to use modulation data to

                    control other parameters.  Modulation and Pitch Bend

                    are usually controlled from the instrument with wheels

                    or levers that the performer can rock back and forth.

                    SUSTAIN:  The same as the sustain pedal on a piano, it

                    will cause the note to sound until the pedal (or other

                    control device) is released.

               The MIDI spec allows for 127 different control parameters,

          although only a small number are currently identified and

          standardized.  In addition, MIDI provides a "system exclusive"

          message.  Each manufacturer is assigned their own unique "sys ex"

          code which allows them to implement custom features without

          interfering with other manufacturers customizations.  Ah ha! you

          say, doesn't that defeat the purpose of a "standard"?  Yes, to an

          extent it does, but remember it was the manufacturers of the

          equipment who pushed for a standard, and allows for innovation

          and differentiation between brands.  And, as stated earlier, you

          must admit that this standard is considerably more consistent

          than a "standard" RS232 interface.

               The preceding constitutes only the broadest description of

          the MIDI protocol, and there are quite a few more features which

          I haven't covered here.  However, you should have a general idea

          of the kinds of data MIDI can handle.  Now I'll tell you some of

          the ways MIDI is used.

                             What is MIDI Used For?

               Ok, we've established that MIDI is both a communications

          protocol and note definition language.  What can it do?

          1.  Control of Instruments

               Any musical instrument can be thought of as having two

          distinct components: the sound producing component and the

          control component.  As an example, the keyboard of a piano, the

          frets on a guitar and the buttons on a clarinet can all be

          thought of as control components.  The piano's strings and

          hammers, the guitar's strings and acoustic body (or magnetic

          pickups if it is electric) and the clarinet's reeds and hollow

          body are all sound producers.  The first application for MIDI

          permits the separation of control and sound production

          components.  The most common (though not the only) MIDI

          controller is the keyboard.  The keyboard generates the NOTE ON

          and NOTE OFF data as well as various other control data (see

          previous section) and passes it on to the sound producing

          section.  The sound producing section could be a synthesizer,

          digital sampler, drum machine, or any other MIDI equipped sound

          producing device.  Most synthesizers combine the sound producing

          device and the keyboard controller in a single physical package.

          However, MIDI permits them two be addressed as two distinct and

          separate sections.

               A single musician at a single keyboard can play many

          different instruments simultaneously.  There are two ways of

          doing this.  The first places several different sound producers

          on the same channel, all responding to the same MIDI data at the

          same time.  This is a process called "layering" and can be used

          to produce full, rich, harmonically complex sounds.  The effect

          is of several different instruments all playing in unison.

               The second technique is called "splitting" the keyboard --

          arbitrarily assigning specific channels to specific notes on the

          keyboard.  This permits different instruments to play different

          music, all under the control of one musician at one keyboard.  As

          an example, the musician might assign the bottom two octaves of

          the keyboard to channel 1 and the rest of the keyboard to channel

          2.  If a digital sampler set to reproduce the sound of a bass is

          assigned to channel 1, and a synthesizer producing a piano sound

          is assigned to channel 2, the musician will be able to play the

          bass line accompaniment with his left hand while playing the

          piano lead with his right.

               Note that when instruments are layered, an unlimited number

          of instruments may be played.  However, when the keyboard is

          split, the maximum number of instruments that may be controlled

          is limited to the maximum number of MIDI channels -- 16.

          2. Sequencers

               Another obvious application for MIDI is the storing of the

          MIDI data stream for later playback -- a process known as

          sequencing.  This task may be performed either by a dedicated

          piece of hardware (called, of course, a "sequencer") or by

          general purpose computers equipped with the appropriate software

          and interfacing.

               Most sequencers allow editing of the MIDI data -- wrong

          notes can be corrected, new material can be entered one note at a

          time, and sections can be rearranged, moved or copied (much like

          a word processor).  Almost all sequencers allow for transposition

          (changing key) and tempo changes.  Some will "auto-correct" so

          that all notes are played exactly on the beat, eliminating any

          sloppiness in playing.

               Since MIDI provides 16 unique channels, 16 different

          instruments can be controlled simultaneously, allowing the

          sequencer to function like a multi-track tape recorder.  Each

          instrument is "played" into the sequencer individually on a

          different channel.  When all the parts have been entered, the

          sequencer can play them back all at the same time, in effect

          creating a one-man band (or one-man philharmonic orchestra).

               Finally, since MIDI was developed as a professional and

          semiprofessional musical tool, several features required for

          recording are supported.  Most sequencers allow for some form of

          tape sync.  In the most basic form of tape sync, the sequencer

          provides a synchronization signal which can be laid down on one

          track of a multi-track tape recorder.  When new tracks are laid

          down, the sequencer can synchronize to the previously recorded

          material.  This makes multi-track recording, over-dubbing, and

          similar recording tricks much easier.  The MIDI spec also defines

          a MIDI SONG POINTER, which can be thought of as "mile markers" in

          the music.  A sequencer that supports MIDI SONG POINTERS is

          capable of automated punch-in and punch-out -- the process of

          inserting new material into a previously recorded track.

          3.  Librarian Software

               One of the uses manufacturers of MIDI instruments make of

          the SYSTEM EXCLUSIVE command is for data dumps; literally

          "dumping" all the parameter data needed to define sounds and

          setups out the MIDI line on command.  Software that stores this

          data for later recall is called Librarian software.  Most

          librarians are not limited to merely storing and retrieving the

          dumped data, but are also capable of editing specific patch

          parameters -- a task which is more easily performed on a computer

          with a full keyboard and video display than on the more limited

          displays and entry devices available on the synthesizers

          themselves.

               A special form of librarian, generally called a Sound

          Modeling Program, use the SYSTEM EXCLUSIVE dump command to obtain

          wave sample data from digital samplers (see the section on

          Hardware).  The wave sample can then be displayed, manipulated,

          stored and retrieved by the librarian.  "Serious" sampling with

          digital samplers virtually mandates the use of some form of Sound

          Modeling Program.

          4.  Notation Software

               Notation software takes the MIDI note data and translates it

          into conventional music notation which can be displayed on the

          screen or printed on a dot matrix or laser printer.  It allows a

          musician to play music in on the controller keyboard in real time

          and get finished musical scores out.  Alternatively, music can be

          entered in notational form on the computer keyboard using

          wordprocessor-like commands, and the finished result can be heard

          played on a MIDI equipped synthesizer.

             Copyright 1987 by Paul Tauger.  This article may be freely

          exchanged, copied and/or distributed provided it is done without

                                       charge.
          5.  Other Applications

               Lately, MIDI has also found application in non-musical

          functions, e.g. controlling mixing boards, stage lighting and

          sound processing equipment (reverbs, digital delays, etc.).

                               Problems with MIDI

               As powerful a tool as MIDI is, it is not totally without

          problems.  What follows are a few cautionary notes:

          1.  As already mentioned, MIDI defines note duration with two

          separate data commands: NOTE ON and NOTE OFF.  The possibility of

          a NOTE ON being transmitted without a corresponding NOTE OFF

          following is an always present danger.  Data can get garbled

          during transmission, lines become unplugged (the MIDI standard

          utilizes 5-pin DIN connectors which have a nasty habit of

          loosening in their sockets), channels accidentally get switched,

          etc.  Without a NOTE OFF command, the note will continue to sound

          for ever.  This can be a major annoyance in a recording session

          (more than annoying if it occurs during that once-in-a-lifetime

          hot set) and in live performance, well, you get the idea.

          Various manufacturers have come up with different solutions to

          the problem, the most common being a button which, when pressed,

          produces an ALL NOTES OFF command.  This will, of course, silence

          the offending note, but silences all the other notes in the

          process.  Because the two note NOTE ON/NOTE OFF structure is

          intrinsic to the MIDI spec, we will just have to live with the

          occasional stuck note.

          2.  MIDI transmits at 31.2k baud.  A little math shows that MIDI

          is capable of sending approximately 1000 notes per second.  This

          is obviously more than any musician can ever play.  However, when

          you divide this capacity among 16 channels, add in the data

          stream produced by controllers such as pitch benders and

          modulation wheels, then throw in a few program changes for good

          measure, you have the possibility of overrunning the data.  To be

          honest, I've never heard of this happening, but the possibility

          is still there.

          3.  Most MIDI instruments contain a MIDI-in jack for receiving

          data, a MIDI-out jack for transmitting data, and a MIDI-thru jack

          for passing MIDI data along to another instrument.  When

          instruments are daisy-chained together, a perceivable delay

          develops between the first and last instrument in the chain.

          This is the infamous "MIDI delay" of which you may have heard.

          This delay can be eliminated by using a device known as a "MIDI

          Thru Box".  This is an active splitter that accepts one MIDI

          input and divides it into 4,6 or more MIDI outputs, thereby

          assuring that all instruments receive the MIDI signal at the same

          time.  Does it solve the problem?  You bet!  Does it cost more

          money?  You bet!

          4.  Another problem, frequently mistaken for MIDI delay, is

          inherent in some MIDI synthesizers.  Remember that the keys on

          the keyboard are scanned sequentially, in the same manner as a

          computer keyboard.  In some brands of keyboard synthesizers, the

          internal electronics introduce their own delays in translating

          the key presses into sounds.  Though not specifically a MIDI

          problem, it is a problem none the less, and is particularly

          evident when the musician "grabs" large chords consisting of many

          notes.  Fortunately, this problem is recognized as a hardware

          "bug" and is usually corrected by the manufacturer (after enough

          people complain).

          5.  By its very nature, MIDI is designed to permit one controller

          on line at a time.  More than one controller on line will result

          in inevitable data collisions with the resultant garbling of

          data.  Think of two computers sending data to two printers at the

          same time.  There are devices available which mediate data

          contention between two MIDI controllers.  Generally called Midi

          Mergers, they are another relatively expensive solution to what

          seems like a simple problem.

          6.  Though the MIDI protocol is clearly defined in the spec,

          computer storage schemes are left up to the individual software

          producer.  There is no MIDI equivalent of an ASCII or EBDIC file.

          Consequently, MIDI data files produced by one piece of software

          can not be read by another.  This would be fine if there were

          such a thing as a program that did everything (and did it well).

          However, as in the case of the "integrated" packages that

          combined word processors, spread sheets, data bases and

          communications software all in one box, such as thing simply

          doesn't exist.  Right now, the only way to exchange MIDI data

          between programs is by transmitting the data over a physical MIDI

          data line between two computers.

          7.  As mentioned earlier, the MIDI spec provides considerable

          latitude to manufacturers who want to incorporate custom features

          in their instruments.  Consequently, MIDI is afflicted with

          "creeping non-standardization".  There are already controller

          number conflicts between some of the largest instrument

          manufacturers, and the SYSTEM EXCLUSIVE command guarantees that

          no single librarian program will work with all synthesizers.

          8.  Now for what I see as the major problem with MIDI - MONEY!

          Until the electronic revolution, quality musical instruments were

          carefully crafted, often handmade, and very expensive.  After

          all, great instrument making is an art.  Consequently, musicians

          have become accustomed to paying a lot of money for the

          instruments they play.  This tradition has been maintained by

          many manufacturers of mass-produced electronic instruments.

          There are exceptions (see the description of the Casio CZ-101 in

          the Hardware section), but for the most part, the sales price of

          a piece of electronic musical gear frequently does not bear any

          correspondence to the cost of its manufacture.  Fortunately, the

          current trend is towards dropping prices.  However, walk into any

          music store and you will see MIDI cables (2 DIN plugs and 10 feet

          of 2 conductor shield cable) for $25 or more.  Though good MIDI

          software tends to be very expensive, it should be remembered that

          MIDI software publishers have a much more limited market for

          their product than publishers of more common business-oriented

          packages.

                        A Brief (and Biased) Hardware Catalog

               I would like to conclude this report with a description of

          the types of MIDI hardware currently available.  Hardware

          selection is a very personal decision, and what I say here

          (beyond the basic descriptions) is necessarily biased by my own

          preferences.  Here goes:

          1.  Sound Producing Devices

               The devices which produce the actual sounds can be divided

          into two basic categories:

                    -  Synthesizers - devices which generate basic sound

                    waveforms, and, by manipulating various parameters of

                    the sound (envelope, modulation, etc.) can produce a

                    diversity of tonal textures and colors.

                    -  Samplers - devices that digitally record, or sample,

                    a sound, and then play it back at pitches determined by

                    the controller.

               Synthesizers can be divided into two broad categories.

          Analog synthesizer use conventional oscillators and filters to

          produce different sound waveforms, e.g. sine waves, square waves,

          triangle waves, etc.  Digital synthesizers "store" a digitally

          encoded waveform in ROM, and produce their sounds by reading the

          waveform out to D-to-A convertor.  Generally, analog synthesizers

          are thought of as producing "warmer" sounds than their digital

          counterparts.  Some common synthesizers are:

               Yamaha DX-7 (approx. $1700) - The DX-7 has become something

               of a "standard" for digital synthesis, and is used by many

               professional musicians.  Most librarian software supports

               this machine.

               Casio CZ-101 (approx. $300) - Casio has a complete line of

               digital synthesizers, but the CZ-101, in my opinion, offers

               more "bang for the buck" than anything else on the market.

               This machine is supported by many librarians, is capable of

               producing an astonishing range of sounds and is an excellent

               "starter" for anyone interested in testing the waters of

               electronic music.  Two drawbacks:  it has a small keyboard

               that is difficult to play, and does not support note

               velocity; all notes default to a velocity of 64.

               Samplers are available in a wide range of prices and

               capabilities.  Factors to be considered in purchasing a sampler:

               1 - Sample width.  The more bits per sample, the better the

               resolution, dynamic range, and fidelity. This rule is not

               written in stone, however, as many manufacturers have

               developed data compression algorithms that allow them to

               squeeze more information out of smaller width samples, and a

               12-bit machine may not necessarily sound better than an

               8-bit machine.

               2 - Sampling rate.  Higher sampling rates permit the

               reproduction of higher frequency sound data.  The Nyquist

               rule specifies a sampling rate 2-1/2 times the frequency of

               the highest sound to be sampled, i.e. to sample the full

               audible audio spectrum (20 Hz to 20,000 Hz), a sampler

               should have a sampling rate of (2.5 * 20,000) or 50,000

               samples per second.

               3 - Number of active samples.  The sound of a "real"

               instrument can not be reproduced by sampling only one note

               and "stretching" it across the entire keyboard.  Many

               samples taken at many different pitches are necessary to

               effectively simulate the distinctive voice of an instrument.

               Some samplers provide only a single sample at a time which

               must be stretched.  Others provide as many as 64 active

               samples at a time which may be assigned to specific sections

               of the keyboard as needed.

               4 - Available memory.  Samplers with a lot of memory can

               allow higher sampling frequencies, longer samples, and more

               active samples.

               Digital Samplers are "where the action is" and new machines

          are being introduced all the time.  Some inexpensive samples of

          samplers:

               Akai  S612 (approx. $1000 with disk storage):  The least

               expensive "real" sampler (as contrasted with several

               sampling toys that have recently hit the market) the S612 is

               also available in an expanded version called the S900 for

               approximately $3000. The S612 is limited to one active

               sample at a time.  Sampling rate is also limited, which

               restricts its ability to sample high frequency sounds.  In

               addition, it is a rack-mounted device which requires a MIDI

               keyboard to control it.  It is, however, a fully implemented

               sampler for a minimum price, and constitutes a good

               entry-level machine for those who want to experiment with

               sampling.

               Ensoniq Mirage (approx. $1700 with keyboard):  The Mirage is

               a versatile instrument that offers a user-selectable sample

               rates up to 30 kHz with up to 16 active samples. The machine

               also has a full sound modification section consisting of the

               traditional envelope and filter synthesizer controls,

               permitting the user considerable flexibility in customizing

               sound samples. Ensoniq offers a large library of factory

               samples on 3-1/2" disk (disk drive included with the Mirage)

               which range in quality from adequate to extraordinary.  A

               good test for a sampler is the ability to recreate the sound

               of an acoustic piano, as pianos produce extremely complex

               waveforms.  The Mirage does a very credible job with pianos,

               as well as other acoustic instruments.  The Mirage is also

               available in a less expensive rack mount version (no

               keyboard).

               Sequential Circuits Prophet 2000 (approx. $2500): 12-bit

               sampler with extensive MIDI implementation.  Sampling rate

               user-switchable up to 41 kHz.  There has been some criticism

               of the quality of factory-produced library samples,  but the

               machine is capable of extremely high-quality sampling.

               Emu Emulator II (approx. $8000):  A very high quality

               sampler the uses a proprietary data encoding scheme to

               purportedly wring 14-bit resolution out of 8-bit samples.

               The Emulator was one of the first "affordable" samplers (as

               compared with the $50K - $100K Fairlight and Synclavier) and

               has seen extensive use in professional recording and live

               performance.

               Drum machines are specialized devices that simulate the

          sound of a drum set.  The sounds are ROM-based digital samples,

          though some machines permit the user to sample their own sounds.

          All drum machines allow the user to define a number of patterns

          which can be strung together to form "songs".  A representative

          drum machine:

               Yamaha RX-15 (approx. $400) - Has 16 different drum sounds

               (only 12 available at the same time), memory for up to 99

               patterns and 10 songs (depending on complexity).  Good MIDI

               implementation, though incapable of MIDI sys ex dumps.  Also

               available as the RX-11 (approx. $700) with complete MIDI

               implementation.

          2 - Keyboard Controllers

               Keyboard controllers produce no sounds by themselves but

          generate the MIDI data necessary to control MIDI sound-producing

          devices.  Keyboard controllers have "actions" that provide a feel

          similar to traditional pianos.

               MIDI data can also be generated by non-keyboard devices,

          including guitars, drums and various wind instruments.  Devices

          called "pitch riders" can translate an analog sound input into

          MIDI data output.

          3 - Computers

               This is a volatile area for discussion, with proponents of

          different brands fiercely loyal to their machines (as I am

          fiercely loyal to mine - an IBM PC-XT).  Anyway, here's a quick

          run down:

               Inexpensive Machines:

               Commodore 64/128:  Many software packages are available, as

               well as different interface options.  The machine's 64K of

               memory presents a limitation for sequencing and scoring

               programs, but low cost of the Commodores makes for them good

               MIDI "starter" systems.  If you are considering the

               Commodore, avoid software that claims it can use the 64's

               internal sound chip to produce "real professional

               synthesizer sounds".  The sound chip on the 64 is quite

               clever and very versatile, but is limited to three voice

               polyphony and has severely restricted sound modifying

               capabilities.  It is not a substitute for a synthesizer by

               itself.  Passport and Dr. T are two publishers of quality

               MIDI software for the Commodore.

               Low-cost Atari's:  Same limitations as the Commodore, though

               perhaps with fewer quality software packages available.

               Noted exception: Hybrid Arts produces well recognized and

               well respected software, though unfortunately, only for the

               Atari line.

               Apple II - About on a par with the cheap Atari's from a

               music standpoint.  48K memory presents severe limitations.

               Moderately Priced Machines:

               Only two worth considering - the Amiga and the Atari ST.

               The Atari has slightly more software packages available and

               offers a built-in MIDI interface.  The MIDI interface is an

               extra-cost option on the Amiga.  I'll avoid jumping into the

               Atari vs. Amiga war by saying both machines offer good value

               and are well-suited for MIDI and other music applications.

               More Expensive Machines:

               Macintosh:  In fairness, I must confess to a certain amount

               of anti-Mac prejudice.  My criticisms are not new:

               expensive peripherals, up-until-recently closed

               architecture, hard-to-support serial bus, operating system

               designed for computerphobes, etc.  However, if you like it

               you like it, and there are some excellent professional music

               packages available for it.  However, my preference, hands

               down, is:

               IBM PC-XT (and PC clones):  The PC offers a great variety of

               powerful, professional music software packages, and a

               variety of flexible MIDI interfaces are available for it.

               It is also the only machine which will run Personal

               Composer, the only notation program I've seen which actually

               works.  There are other notation programs out, but they are

               so riddled with bugs as to be almost unusable, or else are

               so limited in their implementations as to impose severe

               restrictions on composers.  (I will happily retract the

               preceding statements upon compelling evidence to the

               contrary). One program worth mentioning is Texture, a

               sequencer which has become the de facto standard of

               professional musicians.

                                     Final Words

               As stated at the outset, MIDI is a very large topic to be

          tackled in a single report.  I hope I have presented enough

          information to give the MIDI neophyte a basic understanding of

          the topic.  Let me also remind you that the "review" material

          presented here is highly subjective, particularly in the

          "hardware" section.  There are many more fine instruments and

          software packages which I have not mentioned here.

               A good source for information on MIDI and electronic music

          in general is KEYBOARD magazine, which publishes reviews of

          hardware and software, features on all aspects of keyboard music

          (both acoustic and electronic), occasional how-to articles, etc.

               I hope some of you who read this will be motivated to

          experiment with MIDI.  The control capabilities of sequencers and

          the sound generating abilities of the various synthesizers and

          samplers put the ability to create professional sounding music in

          the hands of almost anyone.  If there is enough interest, I can

          prepare occasional reports that explore specific areas of

          electronic music production in greater detail.  Messages for me

          can be left at The Sleepy Hollow BBS, 213-859-9334 (24 hours,

          1200 baud, 8-bit, no parity, 1 stop bit), which, incidentally, is

          the finest BBS I've encountered and is run by a knowledgeable and

          dedicated Sysop.


             Copyright 1987 by Paul Tauger.  This article may be freely

          exchanged, copied and/or distributed provided it is done without

                                       charge.
