S/T SIXTEEN/THIRTY-TWO Applications September 1985 By The Power Of MIDI Richard Kaller At last, the STs are finally here. Tear open the packing and gently lift my 520 out of the box. Now let's see what hardware made it to the production model. It has 512K RAM with a direct memory access rate of 1.3 meg/sec, an RS-232C serial interface, a Centronics interface for printers, a hard disk interface, a monitor port; and it still has MIDI, not as a peripheral, but with the hardware and software routines built in. For those of you who may not have heard of MIDI, it stands for Musical Instrument Digital Interface. MIDI is a standard, covering both hardware and software protocol, agreed upon and designed by musical instrument manufacturers, so that instru- ments such as synthesizers and drum machines could talk with each other. Because all of these MIDI equipped instruments are really computers, dedi- cated to music but still computers, MIDI also enables them to talk with personal computers like the ST. What's this mean for you and me? Well, if you're a musician and you haven't heard about the power hidden in a computer, listen closely. Your ST computer can function as a multi-track recording setup for MIDI-equipped instruments, in a small space at home, simulating most of the capabilities of a commercial tape recorder, like autolocate, punch-in and punch-out, overdubbing, and track bouncing. The main difference is that MIDI is memorizing sequences of note-on and note-off com- mands, instead of audio signals quantitized to digital data. (More on the significance of this later.) To play what you have recorded, you simply reverse the flow of data with the computer feeding the information back to the voices in the synth or drum machine, rather than driving an audio signal through a conventional stereo system. With the ability to send parts addressed to 16 different channels over one cable, you can playback as many parts in real-time as you have seperately assign- able voices. After recording, you can edit the music in much the same manner as a word processor lets you manipulate text. Repeat a phrase here, cut out a note there, even change the tempo or transpose the key; things that can't be done easily on tape. (Editing functions are also extremely useful in creating and maintaining patch libraries, blocks of data that define the tonal qualities of notes, as opposed to their pitch.) The next step is hard copy. A graphics printer can give you instant sheet music, complete with all the latest edits you've made. No more time spent handcopying music notation. No more trying to remember just what notes you played during that improvised solo every- body loved. On top of all this, you get accurate, high speed, easy access, massive storage for all MIDI data on disk. I think we all are familiar with the trials and tribulations of using cassette recorders for program and data storage. What's next? If you're not a musician but always wanted to be, MIDI releases the tutorial abilities of computers to benefit young and old alike. A computer never gets grumpy having to cor- rect beginners' mistakes and is discerning enough to catch any mistruck notes or the slightest fluc- tuations in tempo. Even if you can't play a lick, most MIDI recording software allows you to enter notes step-by-step to be played back in real-time. This is slow, but also valuable for correcting timing errors. Or if you want to sit back and listen, there are floppy disks of pre-recorded music; boot up the disk and voila! your very own computer-driven Muzak. Now, we can be composer, conductor, performer, and audience rolled into one. This is great for musicians and music lovers, but what about those who can't carry a tune in a bucket (or don't want to)? What else does MIDI have to offer? Due to the nature of MIDI, it can be used to direct much more than music. Remem- ber I said that MIDI doesn't use converted audio signals. MIDI code uses some nibbles (half bytes) to define channels, a few more to turn notes on and off, and small blocks, maybe 16 or 32 bytes long, to simultaneously change all parameters. If you substitute 'events' for 'notes' and 'control panel settings' for 'patches', it becomes clear that MIDI could turn on or off any properly equipped device, or make adjustments to its controls. In fact, it is already being used to control stage lighting during performances. Since you can turn lights on and off onstage, why not in your home or workplace, according to some schedule or in response to exter- nal events? If you can control lighting, why not systems such as heating, air-conditioning, watering, security, and appliances. This is truly a situation limited only by our imaginations. Future columns will deal more closely with the details of MIDI; how it works, where it has been, and where it is going. Interspersed in all this will be reviews of MIDI software, books, and existing instruments; previews of new controllers and controllees; interviews with programmers, musicians and technicians; and any other views that might be appropriate. I will also devote a column here and there to answer letters, so write me with any questions or comments. Because of MIDI's parentage, the emphasis for now will be on music, but you will be the one to say where we will go with the power of MIDI.