Atari AMY
Encyclopedia
Atari
's AMY (or Amy) was a 64-oscillator additive synthesizer
implemented as a single-IC sound chip
. For a time, AMY was slated to be included in newer versions of the Atari 8-bit family
, but this did not occur before development of that line was discontinued. The technology was later sold, but when the new owners started to introduce it as a product, Atari sued, and work on the project ended.
s of a given frequency. The sine waves were created by looking up the amplitude at a given time from a 16-bit table stored in ROM
, rather than calculating the amplitude using math hardware. The signals could then be mixed together to perform additive synthesis
. The AMY also included a number of ramp generators that could be used to smoothly modify the amplitude or frequency of a given oscillator over a given time. There were only 8 frequency ramps, as they appeared to be more difficult to build during the design stage.
Sounds were created by selecting one of the oscillators to be the master channel, and then attaching other oscillators and ramps to it slaved to some multiple of the fundamental frequency. Sound programs then sent the AMY a series of instructions setting the master frequency, and instructions on how quickly to ramp to new values. The output of the multiple oscillators was then summed and sent to output. The AMY allowed the oscillators to be combined in any fashion, two at a time, to produce up to 8 output channels. The output was then converted to analog in a separate (user-provided) digital-to-analog converter
.
While the additive synth system works well for sounds with a narrow spectrum, it is not useful for wider spectrum sounds like white noise
. To fill the need to generate the sounds of explosions, jet engines and similar sounds, AMY also included random noise generators that could be mixed into the master oscillator to randomly shift the output.
The AMY was particularly useful for digital sound playback given the limited memory and bandwidth resources available at the time. An input sample could be run through an Fast Fourier transform
to extract the spectral pattern, and then that pattern could be input to the AMY to set up the oscillators. The result is a highly accurate rendition of the original signal, but reduced to a handful of parameters that could easily be stored. That pattern could then be shifted up or down simply by changing the frequency of the master oscillator, with the slaved oscillators following those changes naturally. In one experiment, telephone-quality voice audio was produced using this method, requiring only 2400 baud of bandwidth.
during the 1970s, which produced a similar system that required several racks of equipment to implement the so-called "Alles Machine". Several of Alles' solutions to particularly thorny implementation issues were used in GAZA.
At the time, it was intended to be used in a new Motorola 68000
machine being designed, which also used a new graphics chip known as "Rainbow". The GAZA team was led by Gary Sikorski, and the primary architects were Scott Foster and Steve Saunders. The single-chip implementation was handled by Sam Nicolino, while John Palevich and Tom Zimmerman wrote support software.
AMY was announced in an Atari-internal mailing list in March 1984, with a short description and a June estimated time frame for shipping the first version, the AMY-1, with volume quantities available that December. The first versions would run up to 5 MHz, but a second run improved this to 10 MHz. Spec sheets used 4 and 8 MHz and basic clock speeds, respectively. Like most ATG projects, AMY was not the result of a specific product requirement, and at the time there were no planned uses.
bought Atari from Warner Communications
and quickly dismantled the majority of Atari's engineering departments. During this process they came across the AMY team, who persuaded them to adapt it for use in the 8-bit machines
. These machine's sound capabilities were lacking in comparison to contemporary machines like the Commodore 64
, which the AMY would address convincingly. The result was the 65XEM project, which combined the existing 65XE with the AMY.
First shown publicly at the Consumer Electronics Show
in January 1985, the XEM carried a premium $30 to $50 above the basic 65XE, which was also being launched at the same show. However, as the company's focus quickly shifted from the 8-bit line to the new Atari ST
's being launched at the same time, the XEM was shunted aside and never released commercially. A few prototypes were built, some of which later found their way into the hands of private collectors.
Atari
Atari is a corporate and brand name owned by several entities since its inception in 1972. It is currently owned by Atari Interactive, a wholly owned subsidiary of the French publisher Atari, SA . The original Atari, Inc. was founded in 1972 by Nolan Bushnell and Ted Dabney. It was a pioneer in...
's AMY (or Amy) was a 64-oscillator additive synthesizer
Additive synthesis
Additive synthesis is a technique of sound synthesis that creates musical timbre by explicitly adding sinusoidal overtones together.The timbre of an instrument is composed of multiple harmonic or inharmonic partials , of different frequencies and amplitudes, that change over time...
implemented as a single-IC sound chip
Sound chip
A sound chip is an integrated circuit designed to produce sound . It might be doing this through digital, analog or mixed-mode electronics...
. For a time, AMY was slated to be included in newer versions of the Atari 8-bit family
Atari 8-bit family
The Atari 8-bit family is a series of 8-bit home computers manufactured from 1979 to 1992. All are based on the MOS Technology 6502 CPU and were the first home computers designed with custom coprocessor chips...
, but this did not occur before development of that line was discontinued. The technology was later sold, but when the new owners started to introduce it as a product, Atari sued, and work on the project ended.
Description
The AMY was based around a bank of 64 oscillators, which emit sine waveSine wave
The sine wave or sinusoid is a mathematical function that describes a smooth repetitive oscillation. It occurs often in pure mathematics, as well as physics, signal processing, electrical engineering and many other fields...
s of a given frequency. The sine waves were created by looking up the amplitude at a given time from a 16-bit table stored in ROM
Read-only memory
Read-only memory is a class of storage medium used in computers and other electronic devices. Data stored in ROM cannot be modified, or can be modified only slowly or with difficulty, so it is mainly used to distribute firmware .In its strictest sense, ROM refers only...
, rather than calculating the amplitude using math hardware. The signals could then be mixed together to perform additive synthesis
Additive synthesis
Additive synthesis is a technique of sound synthesis that creates musical timbre by explicitly adding sinusoidal overtones together.The timbre of an instrument is composed of multiple harmonic or inharmonic partials , of different frequencies and amplitudes, that change over time...
. The AMY also included a number of ramp generators that could be used to smoothly modify the amplitude or frequency of a given oscillator over a given time. There were only 8 frequency ramps, as they appeared to be more difficult to build during the design stage.
Sounds were created by selecting one of the oscillators to be the master channel, and then attaching other oscillators and ramps to it slaved to some multiple of the fundamental frequency. Sound programs then sent the AMY a series of instructions setting the master frequency, and instructions on how quickly to ramp to new values. The output of the multiple oscillators was then summed and sent to output. The AMY allowed the oscillators to be combined in any fashion, two at a time, to produce up to 8 output channels. The output was then converted to analog in a separate (user-provided) digital-to-analog converter
Digital-to-analog converter
In electronics, a digital-to-analog converter is a device that converts a digital code to an analog signal . An analog-to-digital converter performs the reverse operation...
.
While the additive synth system works well for sounds with a narrow spectrum, it is not useful for wider spectrum sounds like white noise
White noise
White noise is a random signal with a flat power spectral density. In other words, the signal contains equal power within a fixed bandwidth at any center frequency...
. To fill the need to generate the sounds of explosions, jet engines and similar sounds, AMY also included random noise generators that could be mixed into the master oscillator to randomly shift the output.
The AMY was particularly useful for digital sound playback given the limited memory and bandwidth resources available at the time. An input sample could be run through an Fast Fourier transform
Fast Fourier transform
A fast Fourier transform is an efficient algorithm to compute the discrete Fourier transform and its inverse. "The FFT has been called the most important numerical algorithm of our lifetime ." There are many distinct FFT algorithms involving a wide range of mathematics, from simple...
to extract the spectral pattern, and then that pattern could be input to the AMY to set up the oscillators. The result is a highly accurate rendition of the original signal, but reduced to a handful of parameters that could easily be stored. That pattern could then be shifted up or down simply by changing the frequency of the master oscillator, with the slaved oscillators following those changes naturally. In one experiment, telephone-quality voice audio was produced using this method, requiring only 2400 baud of bandwidth.
Development at Atari
The AMY was developed as an experiment within the Advanced Technologies Group (ATG) of Atari, starting in 1983 and then known as Project GAZA. The system design was based on Hal Alles' experimental work at Bell LabsBell Labs
Bell Laboratories is the research and development subsidiary of the French-owned Alcatel-Lucent and previously of the American Telephone & Telegraph Company , half-owned through its Western Electric manufacturing subsidiary.Bell Laboratories operates its...
during the 1970s, which produced a similar system that required several racks of equipment to implement the so-called "Alles Machine". Several of Alles' solutions to particularly thorny implementation issues were used in GAZA.
At the time, it was intended to be used in a new Motorola 68000
Motorola 68000
The Motorola 68000 is a 16/32-bit CISC microprocessor core designed and marketed by Freescale Semiconductor...
machine being designed, which also used a new graphics chip known as "Rainbow". The GAZA team was led by Gary Sikorski, and the primary architects were Scott Foster and Steve Saunders. The single-chip implementation was handled by Sam Nicolino, while John Palevich and Tom Zimmerman wrote support software.
AMY was announced in an Atari-internal mailing list in March 1984, with a short description and a June estimated time frame for shipping the first version, the AMY-1, with volume quantities available that December. The first versions would run up to 5 MHz, but a second run improved this to 10 MHz. Spec sheets used 4 and 8 MHz and basic clock speeds, respectively. Like most ATG projects, AMY was not the result of a specific product requirement, and at the time there were no planned uses.
65XEM
In July, Jack TramielJack Tramiel
Jack Tramiel is an American businessman, best known for founding Commodore International - manufacturer of the Commodore PET, Commodore 64, Commodore 128, Commodore Amiga, and other Commodore models of home computers.-Biography:...
bought Atari from Warner Communications
Warner Communications
Warner Communications or Warner Communications, Inc. was established in 1971 when Kinney National Company spun off its non-entertainment assets, due to a financial scandal over its parking operations and changed its name....
and quickly dismantled the majority of Atari's engineering departments. During this process they came across the AMY team, who persuaded them to adapt it for use in the 8-bit machines
Atari 8-bit family
The Atari 8-bit family is a series of 8-bit home computers manufactured from 1979 to 1992. All are based on the MOS Technology 6502 CPU and were the first home computers designed with custom coprocessor chips...
. These machine's sound capabilities were lacking in comparison to contemporary machines like the Commodore 64
Commodore 64
The Commodore 64 is an 8-bit home computer introduced by Commodore International in January 1982.Volume production started in the spring of 1982, with machines being released on to the market in August at a price of US$595...
, which the AMY would address convincingly. The result was the 65XEM project, which combined the existing 65XE with the AMY.
First shown publicly at the Consumer Electronics Show
Consumer Electronics Show
The International Consumer Electronics Show is a major technology-related trade show held each January in the Las Vegas Convention Center, Las Vegas, Nevada, United States. Not open to the public, the Consumer Electronics Association-sponsored show typically hosts previews of products and new...
in January 1985, the XEM carried a premium $30 to $50 above the basic 65XE, which was also being launched at the same show. However, as the company's focus quickly shifted from the 8-bit line to the new Atari ST
Atari ST
The Atari ST is a home/personal computer that was released by Atari Corporation in 1985 and commercially available from that summer into the early 1990s. The "ST" officially stands for "Sixteen/Thirty-two", which referred to the Motorola 68000's 16-bit external bus and 32-bit internals...
's being launched at the same time, the XEM was shunted aside and never released commercially. A few prototypes were built, some of which later found their way into the hands of private collectors.