A direct descendent in a prestigious line
of electronic musical instruments, the Buchla 700 continues a tradition
of combining inventive musical.and instrumental concepts with state-of-the-art
electronics technology.
THE 700'S ARCHITECTURE includes four dedicated computers, each of a different
nature, and each optimized to its particular function. The nerve center
of the instrument is a general purpose digital computer. Responsible for
user communication, data processing, and supervisory control, this "host"
computer can be programmed to accommodate varied musical needs.
A second computer "massages" incoming data. It
directs conversion of analog voltages into digital form, discards redundant
information, and transmits essential data to the host computer.
Receiving instructions and data from the host, a third computer (called
the multiple arbitrary function generator) directs the instantaneous progress
of 190 acoustic variables, each with a time resolution of 1/2000 of a second.
This facility enables specification of complex sonic detail and extends
the possibilities for expressive control.
A fourth computer, essentially a pipelined digital
signal processor (DSP), is responsible for producing the 700's twelve voices.
Built into this computer are unusually powerful algorithms for sound generation,
including frequency modulation, waveshape interpolation, and timbre modulation
(unique to the Buchla, this technique significantly augments the electronic
vocabulary.
Custom analog circuitry, with a dynamic range of
100 dB, is used for metering and control of dynamics. Specialized phasing
and location circuitry provides unusual depth and imaging in the resultant
acoustic field and enables independent location of each voice in stereo
space.
Based on sealed membrane technology, the 700's input structure provides
a comprehensive interactive editing and mode selection facility. Position-sensitive
transducers are used to implement conceptual potentiometers, flywheels,
switches, ribbon controllers, and other gesture-sensitive paraphernalia.
Light emitting diodes display the status of touch sensitive keys, and a
super-twisted liquid crystal display indicates the functions and settings
of touch sensitive controls.
Three MIDI ports comprise the 700's primary performance inputs. Under software
control, MIDI channels from any port(s) can be assigned to any of the 700's
voices, thus enabling simultaneous control from multiple MIDI devices (which
might include keyboards, guitar controllers, drum machines, pitch followers,
space wands or personal computers). Other inputs accept control voltages,
pulses, foot pedals, and SMPTE time code. Two RS232 ports provide for communication
with computers, modems, terminals, and printers. Control voltage and pulse
outputs, three MIDI outputs, and special control signal outputs complete
the 700's comprehensive I/O facility.
In addition to the self-contained LCD display, the 700 can drive an external
video monitor that conforms to the EGA standard. This high resolution, multi-color
display, coupled with the 700's extensive input structure and sophisticated
high level music software, provides the instrument with an efficient interactive
editing and performance environment. A built-in 3 1/2 inch disk drive is
used to store data for subsequent retrieval or to facilitate software exchange
with other users. Instrument definitions, tuning tables, waveshape tables,
scores, and high level languages can all be stored on microdisks.
THE 700'S SOFTWARE performs the essential function
of defining the potential interaction between a musician and his instrument.
The 700's primary high-level language (called MIDAS VII) was designed in
conjunction with the hardware; this close integration of hardware and
software contributes to the instrument's ease of operation and unusual versatility.
Designed for use by musicians (programming experience not required),
MIDAS VII is both user-friendly and musically powerful. It incorporates
several distinct facilities, each with its own display, and all sharing
common editing procedures and modes of access. Brief descriptions of some
of these facilities will perhaps suggest the nature and range of MIDAS VII.
The 700's sonic output is defined with the instrument
editor. Here is where the configuration of each of the voices is selected,
the envelopes applied to various functions are determined, and waveshapes
are selected. With as many as four oscillators and six modulators assignable
to each voice, and several synthesis algorithms available, many interconnection
schemes are possible. A configuration number determines how these resources
are connected, and which modulation types apply.
Enveloping capabilities are extensive. For each voice, as many as 15 individual
envelopes may be drawn for application to as many variables (four frequencies,
six modulation indexes, filter frequency, resonance, level, dynamics, and
location). An envelope may consist of as many as 96 segments, with individual
points reacting to different input gestures, arid a variety of conditional
actions (in addition to sustain) possible within each envelope.
All the instrument variables are simultaneously
visible and readily edited by graphic or numeric means. When a desired sound
is realized, it may be labeled, commented, and stored as one instrument
in an "orchestra" of 40 instantly accessible instruments.
A waveshape editor allows the user to create
or modify waveshape tables. A variety of editing techniques is available,
including direct entry of numeric data or harmonic coefficients, as well
as line: bending and curve fitting (particularly efficient forms of drawing).
Fast specialized hardware permits transparent updating of waveshape tables
and enables real time, glitch-free auditioning. With 2 waveshape tables
assigned to each instrument, 24 waveshape tables may be addressed simultaneously
by the 700's 12 voices.
The tuning table editor allows the specification of completely arbitrary
tunings, with any desired intervals and with no restraints on the number
of notes per octave (with no octaves at all if you like). Entries are specified
as musical pitches, with a resolution of 1 cent (1/100 of a semitone). Smart
editing commands can direct the 700's computer to assume much of the detail
work in calculating and entering tuning data. (Just three entries would
be required to create a 17 note equal-interval scale spanning an 88 key
range.)
An assignment table directs the addressing of voices by MIDI ports,
channel numbers, and/or individual keys. Voices may be grouped, and MIDI
output channels may be assigned. Any combination of keyboard divisions may
be specified, and multiple polyphony is supported.
The MIDAS score editor is a compositional facility without equal.
Using linear time notation, a score can be generated through real-time performance
input, and can be edited to the finest detail. Voices can be differentiated
by color; analog variables can be stored and graphically displayed; changes
in instrumentation, tempi, registration, location and tuning can be stored.
Various sorts of data can be organized as collections and stored on disk
by the MIDAS librarian Record types include scores, instrument definitions,
waveshape tables, assignment tables and tuning tables. A unique "conceptual
typewriter" can be used to name records and add comments.
A second computer "massages" incoming data. It
directs conversion of analog voltages into digital form, discards redundant
information, and transmits essential data to the host computer.
