Compiling this post as I have recently scanned original brochures and advertisements and checked online to find less detail than expected. Therefore I have put as much content here in ‘plain text’ and refer you to the PDF files to enjoy the original content and layout. The Link

The DMX-1000 is an ultra-fast 16-bit minicomputer specially designed for audio signal processing applications. It produces audio output by means of a self-contained digital-to­ analog converter. Being completely programmable, it can implement any synthesis or processing method. It contains its own D/A converters and may be controlled by any general-purpose computer.

The DMX-1000 includes one 16-bit DIA conversion channel and a 4K X 16 bit data memory. The unit is contained in a 3½-inch-high standard rack-mountable cabinet. It needs 4 amperes of 60Hz 120V power.

The list price in US dollars, as of August 1979 was $8,995. Refer to PDF price list.

Features:
Computer-Controlled Music
Your general-purpose computer, which can be anything from a hobbyist’s micro to a large timesharing system, controls the DMX-1000. It will perform several voices of music in real time with your computer telling it what notes to ‘ play, at what volume, with what timber, and when. Not only is the performance of the music computer-controlled, but so is the “patching.” Your computer can almost instantly reprogram the DMX-1000, even during performance, in an infinite variety of ways, just as an analog synthesizer is repatched with wires.

Computer control means that you don’t have to perform, as you do with analog synthesizers. Your computer can precisely perform the most complex music from a score that you give it, allowing you to change it incrementally until the performance is perfect. And the ability to synthesize several voices at once reduces or eliminates the need for expensive and time-consuming multi-track recording.

The DMX-1000 Synthesizes Sound In Real Time
A typical computer music system simulates an analog synthesizer at a rate slower than real time. It might take ten minutes or more to calculate a minute’s worth of music, storing the calculated sound samples, which take a lot of room, on a disk, and finally, at the end of the simulation, playing them back through a digital­ to-analog converter in real time. Waiting for such a system can be frustrating, because it takes a long time to hear the effect of a change made in the music. The DMX-1000 synthesizes sound in real time, eliminating the wait, as well as the need for large amounts of expensive fast disk storage for sound samples.

The DMX-1000 Is All Digital
Digital means reliable; the DMX-1000 needs no bias adjustments and can’t drift, so it will stay precise year after year. Digital means noise­ free; noise creeps into every wire, every control, every component of an analog synthesizer. But the only noise in the DMX-1000, no matter how complex the patching, is the low quantization noise in the output conversion process.

The DMX-1000 Is Completely Programmable
Most digital synthesizers, unlike the DMX- 1000, are collections of digital implementations of analog synthesizer components – digital oscillators, envelope
generators, filters, etc. With this kind of synthesizer, it is easy to run out of one sort of unit while those of another type are unused. With most digital
synthesizers you could, for example, use all the oscillators and wish you had more, while most of the filters were idle. What’s more, this synthesizer
architecture limits the choice of sound synthesis methods. Most digital synthesizers will not do waveshaping, for example, because their components were not
designed for it. The DMX-1000, on the other hand, provides a certain amount of computational capacity – 256 general-purpose micro­ instructions, executed each
sample period. You program it to do whatever you wish. If you need only oscillators, you can use the 256 instructions to implement oscillators. If you need one
oscillator and several filters, you can program that. And you can use virtually any synthesis method on the DMX-1000, including waveshaping, since it is
completely programmable.

The DMX-1000 Is High-Precision
The DMX-1000 employs a 16-bit archi­tecture, which provides enough precision for most of the computations used in sound synthesis. There are some cases where
more precision is necessary, and the DMX-1000 provides it. Its multiplier gives a 32-bit product when multiplying two 16-bit numbers; and the ALU will add and
subtract 32-bit quantities.

How It Works (block diagram in PDF)
Another computer controls it through the interface by writing into the data and control memories. The control memory con­ tains writeable microcode, up to 256
32-bit words of it. Each word in the memory is executed in sequence, one per 200ns machine-cycle. There are no branches in the microcode, though individual
instructions can be condi­tionally executed. One pass through the microcode is called a sample cycle, because it is usually used to calculate a sample which is
clocked into the digital-to-analog converters (DACs) near the end of the cycle. When a halt instruction is executed from micro­ code, the sample cycle is over;
after giving the computer interface circuit a chance to update the control and data memories, microcode execution begins again at the first instruction in the
control memory. The sampling rate may be varied by changing the program size; a smaller program runs at a higher sampling rate.

The 16-bit ALU has 17 internal registers and will perform standard arithmetic and logical operations (add, subtract, and, or, etc.). The multiplier will
multiply two signed 16-bit number in one 200ns machine cycle, giving a I 32-bit product. The data memory, 16 bits wide, is used to hold waveform tables (like a
sine wave for an oscillator to sample), state variables (like the current phase of an oscillator), and parameters (like the frequency of an oscillator). It can
be read or written by the ALU once per machine cycle. The 16-bit DAC is normally clocked once per sample cycle. The inputs and outputs of the multiplier and
data memory and the DAC inputs are connected to pipeline registers, which are connected in turn to the ALU’s input or output bus, allowing parallel operation of
all units. During the same 200ns machine cycle, the ALU can be adding two numbers while the multiplier is multiplying two different numbers and the data memory
is fetching a datum.

The DEC Digital PDP-11 could be interfaced with it via the “PDP-11/LSI-11 DMA Interface”. This is historically significant as it helps show a timeline of hardware complimenting high end computers around 1982. The DMA interface:
-Transfers in real time one to four channels of 16-bit audio-rate information between PDP-11 or
LSI-11 and DMX-1000
-Allows DMX-1000 to be used as high-quality audio D/A or A/D converter for PDP-11
-DMX-1000 can process in real time digital audio signals generated by PDP-11 (and vice versa)

The MUSIC-1000 Software was stated to be the most advanced and flexible software system available for any commercial real-time digital synthesizer. Its score language is the same as that of MIT’s well-known MUSIC-11. The orchestra language is designed to be similar to MUSIC-ll’s, but includes extensions for real-time operation, allowing the processing of sound in real time and real-time user control over synthesis and processing operations. MUSIC-1000 takes advantage of the DMX-l000’s unique programmable architecture, allowing the user to arbitrarily patch together networks of signal-processing units. Furthermore, new signal­ processing units may easily be programmed by the user.

A MUSIC-1000 system is suitable for use as a stand-alone computer music synthesis system or as a real-time programmable sound processor for a recording studio. MUSIC- 1000 provides the easiest and least expensive way to build a computer music system from scratch or to add sound processing capability to an existing PDP-11. MUSIC-1000 and the DMX-1000, together with an RT-11 PDP-11 system make a complete computer music system requiring no additional hardware or software.

Extra detail on interfaces:
DMX-1000 HARDWARE OPTIONS

Interfaces
There are three basic interfaces available to connect the DMX-1000 to a master computer: PDP-11/LSI-ll Bus Interfaces,
the RS-232 Interface, and the Basic Parallel Interface. Master computers other than the PDP-11 and LSI-11 must be connected via one of the latter two interfaces.

PDP-11/LSI-ll Interfaces
The DMX-1000-D (for the LSI-11) and the DMX-1000-G (for the PDP-11) are high-speed parallel interfaces that connect the DMX-100-0 to the LSI-11 or PDP-11. The two interfaces ar-e­
software compatible — they look the same to software running on the PDP-11 or LSI-11 and to software running on the DMX-1000.
These interfaces have adequate bandwidth for all synthesis and processing applications1 they will run, in most cases, as fast as the PDP-11 or LSI-11 can send information to the DMX-1000.
They both include a “Reverse Communication Channel” by which the DMX-1000 can send a medium-bandwidth stream of 16-bit words to the PDP-11. The bandwidth is limited by the rate at which the PDP-11 software can absorb data from a parallel interface.
Typically this will be well below the audio rate. Both interfaces also include a real-time clock (which can’t run at the same time as the reverse communication channel) which interrupts the PDP-11 every N DMX-1000 sample cycles, where N may be set under PDP-11 software control to between 1 and 4,095.
The DMX-1000-K and the DMX-1000-L are DMA interfaces for the PDP-11 and LSI-11 respectively. They permit the transfer of data between the DMX-1000 and the PDP-11 or LSI-11 at much higher rates than can be obtained with the parallel interface. They are designed to supplement the DMX-1000-D/G parallel interface, not to replace it1 the standard interface functions (starting and stopping the DMX-1000, and writing its control and data memories, are not available on the DMX-1000-K/L, so the DMA interface must be used together with the parallel one. The
DMX-1000-K/L DMA interface will transfer data in one direction only (the direction may be set under program control) at rates up to small multiples of the audio rate. It will generally be PDP-11 software considerations that limit the transfer rate1 most systems should be able to sustain the transfer of two or four channels of audio-rate information. The DMA interface is intended primarily to allow the DMX-1000 to be used as a
high-fidelity DIA converter (or A/D converter, if the DMX-1000 is equipped with the DMX-1000-J) for the PDP-11. Software, in the form of a small RT-11 program for the PDP-11, is provided with the DMX-1000-K/L interface1 the program loads the DMX-1000 with a microprogram that converts it into a D/A or A/D converter for the PDP-11 The DMA interface may also be used during
DMX-1000 synthesis or real-time processing to feed one or more digital audio signals from the DMX-1000 to the PDP-11, perhaps to be stored on a disk, or from the PDP-11 to the DMX-1000 to be
used in the synthesis process.

RS-232 Interface
The DMX-1000-F RS-232 Interface is easy to connect to a wide variety of master computers, since it connects like a terminal to a standard EIA serial line. It is basically a data-only interface; it does not actively use the RS-232 handshaking signals (see the DMX-1000 Hardware Manual for details). The interface provides a reverse communications channel whereby the DMX-1000 may send low-bandwidth information to the PDP-11. The master computer should be capable of sending a break Ca line space condition lasting more than one character time) in order to be able to initialize the DMX-1000.
The disadvantage of using the RS-232 interface is that it is slow. At 9,600 baud (its maximum speed is 19,200 baud) it allows 175 data memory updates per second. The parallel interface hardware is capable of doing a hundred times that. But the low bandwidth is adequate for many applications.

Basic Parallel Interface
The DMX-1000, purchased with no interface option, comes with a Basic Parallel Interface. This accepts an 8-bit parallel input, strobed by a separate signal; the DMX-1000 provides an output signal that indicates when it is ready to accept another byte of data. All these signals use positive logic and standard TTL logic levels. This set of signals is easy to connect to most parallel interface boards supplied by micro-computer and
mini-computer manufacturers. The connection will not usually require more than a couple chips worth of extra circuitry.

Digital to Analog Converters
The DMX-1000-C Analog Output Channel provides one channel of 16-bit Digital to Analog Conversion. The DMX-1000 comes with one of these channels; an extra one is required for stereo output, three extra for quad. Output is high-impedance, unbalanced, +SV full-scale.

Analog to Digital Converters
The DMX-1000-J Dual Analog Input Channel provides two channels of 16-bit analog-to-digital conversion on one board. Input is high-impedance, unbalanced, ±5V full-scale.

3.0 Delay Memory
The DMX-1000-H Delay Memory provides an extra 64K 16-bit words of data memory for the DMX-1000. This memory is slower than the 4K DMX-lO·OO data memory: it has an action time of 5 machine cycles. But it is still fast enough to be used for storing oscillator and envelope functions as well as delayed digital audio signals.

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The DMX-1010 is the most advanced and powerful audio signal processor available today. It contains two computers-an LSl-11 microcomputer and a super-fast DMX-1000 digital audio signal processor. MUSIC-1000 software allows this system to be programmed easily in an intuitive way for almost any synthesis or processing task.

Features
Real-time digital synthesis and processing of sound
User-oriented software makes system fast and easy to use
Flexible enough to do any type of audio signal processing
16-bit converters and arithmetic for ultra-high fidelity
Stereo input and output-expandable to quad
Price competitive with other systems that do only limited synthesis,

The DMX-1010
A Synthesizer
Flexible Digital Synthesis
The DMX-1010 offers all the advantages of digital synthesis: freedom from noise and drift, precise control of tuning, repeatable and exact parameter settings,
automated patching and programmable control. It also offers a degree of flexibility found, until now, only on analog synthesizers. As a digital synthesizer, the DMX-1010 is unsurpassed. The hardware is much more flexible and programmable than that of any other synthesizer on the market. Where other digital synthesizers limit you to the synthesis techniques pre-envisioned by the designer and built into the hardware, the DMX-1010 signal-processing units are not built directly in hardware but are programmed in software. MUSIC-1000 provides a library of these units (oscillators, filters, noise generators, envelope generators, delay units, etc.) and a way of programming them and patching them together. The power of the analog synthesizer comes from its flexibility. It has different kinds of units
which may be patched together any way at all, allowing unlimited possibilities for creating new sounds. Most digital synthesizers have just oscillators and envelope generators, which drastically limits the number of ways a sound can be generated; most will do only additive synthesis and FM. They are less flexible than analog units and will be obsolete in a few years.

The DMX-1010 offers all the signal processing units found on most analog synthesizers (and more) and
provides a means of patching them together in arbitrary ways. It also allows the user to create new types of units by programming them instead of building them in hardware. The two synthesis methods available on oscillator­ based digital synthesizers, additive synthesis and frequency modulation (FM), leave a lot to bedesired.

Additive synthesis is cumbersome since an envelope must be defined for each of the many partials in a sound; a lot of information is required to define one sound and it’s not easy to figure out what must be changed in the envelopes to make a simple change in the sound. FM is a very powerful and intuitive synthesis method-three or four parameters are enough to describe a large variety of sounds, and the changes in them correspond in simple ways to changes in the sound. But FM has been widely used for the last decade; the sound is familiar and is becoming something of a cliche. The DMX-1010 offers the same unlimited range of synthesis techniques found on an analog synthesizer or computer music system. This includes additive synthesis, FM, waveshaping and various forms of
subtractive synthesis. Anything that can be programmed can be done on the DMX-1010. For example, it will do speech synthesis, which can’t be done on any other
digital synthesizer.

Computer Music Technology
Used as a synthesizer, the DMX-1010 works like a traditional non-real-time computer music system, except that it generates sound in real time. The DMX-1010 brings this computer music technology, which has been in use for a decade at major research centers, into the marketplace for the first time. The composer specifies in advance, at a computer terminal, the piece to be realized. The DMX-1010 synthesizes it. The composer may then change it and resynthesize it.
This mode of operation is more suitable for studio use than for live performance. It makes the DMX- 1010 polyphonic and polytimbral and eliminates the need for sequencers. In many cases it eliminates the need for multi-track tape recording. When a global change needs to be made, like a change in tempo or the addition of an extra measure of music, it’s far easier to edit the MUSIC-1000 score and automatically resynthesize the whole piece than it is to separately resynthesize each of several tracks.
A piece of music to be synthesized is specified to the DMX-1010 in two parts-the score and the orchestra. The score is comparable to a traditional musical score and tells when each note begins, how long it lasts, what its pitch is, and what instrument plays it, with what timbre. The orchestra is a collection of instruments, which are MUSIC-1000 programs describing how each type of sound should be synthesized.
The orchestra may specify that certain synthesis parameters are to come from knobs and switches on the real-time control panel. This gives the user the ability to control the synthesis in real time.

A Sound Processor
Used as an audio signal processor, the DMX-1010 can replace most signal processing units found in a recording studio, including delay lines, phasers, flangers, tape echo units, reverb units, graphic and parametric equalizers, compressors, and limiters. These units are not built directly into the hardware; they are programs in the MUSIC-1000 language.
This makes it easy to change the way they work-to geta different compression curve, for example. It also makes it easy to combine them in various ways­ say, for multi-band compression.

The DMX-1010 makes accessible to post­ production engineers a new range of possible sounds. For the first time, new signal processing techniques can be developed and used without implementing them in hardware; they are simply programmed in
the high-level MUSIC-1000 language. This feature makes the DMX-1010 ideal for post-production processing in a recording studio and for broadcast applications where flexible control over the “sound” is necessary.
Digital Music Systems will soon be offering digital DMX-1010 interfaces for some brands of digital tape recorders. This will allow the DMX-1010 to be used for post-production signal processing without converting the audio signals back in to analog form. Connected to a multi-track digital recorder, the
DMX-1010 can digitally mix 16 tracks down to a two­ track digital master. It will also allow sounds synthesized on the DMX-1000 to be recorded
directly on a digital tape recorder with no intermediate A/D or D/A conversion.

A General-Purpose Audio Computer
The DMX-1010 is a revolutionary new device-an audio computer. It is for sound what a general­ purpose computer is for business or scientific data-a
general-purpose processor. The power of the computer in science and business comes from its being a general-purpose machine that may be customized by each user
in software for his own particular application. Instead of buying a separate machine built specially to perform each separate function (like a computer built
just for processing payrolls), he buys one general-purpose computer and programs it for each of the functions he needs. Buying a single computer is much cheaper
than buying a separate machine for each function. Furthermore, it is a better investment, since it is much easier to adapt to changing conditions and less
likely to become obsolete. The way the computer performs a function may be changed just by reprogramming it. And new functions, even though not foreseen by the
designers of the machine, may be added with software.

The DMX-1010 is the first general-purpose audio computer. Other digital synthesizers and signal processors
have their signal-processing methods built into the hardware. This is like a computer with hardware built just for processing payrolls­ inflexible. The
DMX-lOlO’s signal processing hardware can be programmed to do a wide variety of things, providing all the advantages of a general­ purpose computer over a
special-purpose one. Most commercially available digital synthesizers and processors try to hide the fact that they are basically computers; their designers
seem to feel that users will be confused or put off by dealing with these units as computers (by programming). They conceal their computers behind fancy front
panels that make them look like elaborate analog machines. In doing this they forego a lot of the advantage of digital processing and synthesis-the ease with
which it can be automated and controlled by programming. The DMX-1010 is controlled by programs written by the user in the easy-to-learn MUSIC-1000 language.
Directly controlling the programming of the machine in this way makes it much more powerful and, in the end, easier to use for complex problems. Since the
DMX-1010 is controlled by programming, new features may be added by updating the software. As a DMX-1010 owner you will receive annual software updates
incorporating new features requested by our customers. These updates will be mailed to you on floppy disks.

Other digital-synthesizer manufacturers can add new features in software but are limited by their direct hardware synthesis-they can’t change the signal processing in software; they can only change the way it’s controlled. In the DMX-1010, the basic signal-processing units can be changed in software. This means that new synthesis techniques (like waveshaping) can be added in software. Other synthesizer manufacturers can’t do this.

Educational Services
In spite of its programmability and its power, the DMX-1010 is easy to learn to use. The manuals that come with the machine are complete and easy to understand. The MUSIC-1000 language will be quickly mastered by anyone familiar with analog synthesis or signal processing techniques.
For those desiring instruction in using the DMX- 1010, or in the principles of digital sound synthesis and processing, Digital Music Systems offers a one­ week course. It is given every year in Boston
during August and provides hands-on experience with the DMX-1010. The same course is available to our customers as a one-week in-house training program.