The Motorola DSP56000 (also known as 56K) is a family of digital signal processor (DSP) chips produced by

Motorola Motorola, Inc. () was an American multinational telecommunications company based in Schaumburg, Illinois, United States. After having lost $4.3 billion from 2007 to 2009, the company split into two independent public companies, Motorol ...

Semiconductor (later

Freescale Semiconductor Freescale Semiconductor, Inc. was an American semiconductor manufacturer. It was created by the divestiture of the Semiconductor Products Sector of Motorola in 2004. Freescale focused their integrated circuit products on the automotive, embe ...

then NXP) starting in 1986 with later models are still being produced in the 2020s. The 56k series was quite popular for a time in a number of computers, including the

NeXT Next may refer to: Arts and entertainment Film * ''Next'' (1990 film), an animated short about William Shakespeare * ''Next'' (2007 film), a sci-fi film starring Nicolas Cage * '' Next: A Primer on Urban Painting'', a 2005 documentary film Lit ...

, Atari Falcon030 and

SGI Indigo The Indigo, introduced as the IRIS Indigo, is a line of workstation computers developed and manufactured by Silicon Graphics, Inc. (SGI). SGI first announced the system in July 1991. The Indigo is considered one of the most capable graphics wo ...

workstation A workstation is a special computer designed for technical or scientific applications. Intended primarily to be used by a single user, they are commonly connected to a local area network and run multi-user operating systems. The term ''workstat ...

s all using the 56001. Upgraded 56k versions are still used in audio equipment,

radar Radar is a detection system that uses radio waves to determine the distance ('' ranging''), angle, and radial velocity of objects relative to the site. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, we ...

systems, communications devices (like

mobile phone A mobile phone, cellular phone, cell phone, cellphone, handphone, hand phone or pocket phone, sometimes shortened to simply mobile, cell, or just phone, is a portable telephone that can make and receive calls over a radio frequency link whi ...

s) and various other embedded DSP applications. The 56000 was also used as the basis for the updated 96000, which was not commercially successful.

Technical description

The DSP56000 uses fixed-point arithmetic, with 24-

bit The bit is the most basic unit of information in computing and digital communications. The name is a portmanteau of binary digit. The bit represents a logical state with one of two possible values. These values are most commonly represente ...

program

word A word is a basic element of language that carries an objective or practical meaning, can be used on its own, and is uninterruptible. Despite the fact that language speakers often have an intuitive grasp of what a word is, there is no conse ...

s and 24-bit data words. It includes two 24-bit registers, which can also be referred to as a single 48-bit register. It also includes two 56-bit accumulators, each with an 8-bit "extension" (aka headroom); otherwise, the accumulators are similar to the other 24/48-bit registers. Being a

Modified Harvard architecture The modified Harvard architecture is a variation of the Harvard computer architecture that, unlike the pure Harvard architecture, allows the contents of the instruction memory to be accessed as data. Most modern computers that are documented as ...

processor, the 56k has three memory spaces+ buses (and on-chip memory banks in some of the models): a program memory space/bus and two data memory space/bus. 24 bits was selected as the basic word length because it gave the system a reasonable number range and precision for processing audio (sound), the 56000's main concern. 24 bits correspond to a large

dynamic range Dynamic range (abbreviated DR, DNR, or DYR) is the ratio between the largest and smallest values that a certain quantity can assume. It is often used in the context of Signal (electrical engineering), signals, like sound and light. It is measured ...

, sufficient in the 1980s when

analog-to-digital converter In electronics, an analog-to-digital converter (ADC, A/D, or A-to-D) is a system that converts an analog signal, such as a sound picked up by a microphone or light entering a digital camera, into a digital signal. An ADC may also provide ...

s (ADCs) and

digital-to-analog converter In electronics, a digital-to-analog converter (DAC, D/A, D2A, or D-to-A) is a system that converts a digital signal into an analog signal. An analog-to-digital converter (ADC) performs the reverse function. There are several DAC archit ...

s (DACs) rarely exceeded 20 bits. One example is

ADSL Asymmetric digital subscriber line (ADSL) is a type of digital subscriber line (DSL) technology, a data communications technology that enables faster data transmission over copper telephone lines than a conventional voiceband modem can provide. ...

applications, where filters typically require 20 bits of accuracy. The leftmost four bits are considered ample headroom for calculations. The processor is capable of carrying out 16.5 Million Instructions Per Second (MIPS) at the maximum specified clock speed of , and has hardware support for block-

floating point In computing, floating-point arithmetic (FP) is arithmetic that represents real numbers approximately, using an integer with a fixed precision, called the significand, scaled by an integer exponent of a fixed base. For example, 12.345 can b ...

FFT A fast Fourier transform (FFT) is an algorithm that computes the discrete Fourier transform (DFT) of a sequence, or its inverse (IDFT). Fourier analysis converts a signal from its original domain (often time or space) to a representation in the ...

. It uses

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levels and consumes approximately

Applications and variants

In most designs the 56000 is dedicated to one single task, because digital signal processing using special hardware is mostly

real-time Real-time or real time describes various operations in computing or other processes that must guarantee response times within a specified time (deadline), usually a relatively short time. A real-time process is generally one that happens in defined ...

and does not allow any

interrupt In digital computers, an interrupt (sometimes referred to as a trap) is a request for the processor to ''interrupt'' currently executing code (when permitted), so that the event can be processed in a timely manner. If the request is accepted, ...

ion. For less demanding tasks which are not time-critical, designers normally use a separate CPU or MCU. The 56000 can execute a 1024-point complex Fast Fourier transform (FFT) in 59,898 clock cycles, taking at freescale.com - Product Preview, 24-BIT DIGITAL SIGNAL PROCESSOR, DSP56001A
1997 or a rate of just over 555 operations per second, allowing both realtime decoding and encoding of reasonably advanced audio codecs such as MP3 for direct-to-disc recording purposes. The addition of

SIMD Single instruction, multiple data (SIMD) is a type of parallel processing in Flynn's taxonomy. SIMD can be internal (part of the hardware design) and it can be directly accessible through an instruction set architecture (ISA), but it shoul ...

instructions to most desktop computer CPUs have meant that dedicated DSP chips like the 56000 have partly disappeared from some application fields, but they continue to be used widely in communications and other professional uses. To this end the 56800 series added a complete MCU which created a single-chip "DSPcontroller" solution, while the opposite occurred in the 68456, a

68000 The Motorola 68000 (sometimes shortened to Motorola 68k or m68k and usually pronounced "sixty-eight-thousand") is a 16/32-bit complex instruction set computer (CISC) microprocessor, introduced in 1979 by Motorola Semiconductor Products Secto ...

with a 56000 on it. A still quite prevalent model of the 56000 is the third generation 56300 family, starting with the 56301, which features several models with special applications hard- and firmware built-in, like PCI interface logic, CRC processors, or audio companders. Core clock frequencies ranged up to .''DSP56K Family Overview'', p. 45 ff i
''Beyond DSPs, November 2010''
(freescale/NXP).

References

External links

Freescale Digital Signal Processors

freeware

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for the 56000 architecture
Product-Longevity Program
{{Authority control Digital signal processors Freescale Semiconductor 56000 24-bit microprocessors

Technical description

Applications and variants

References

Further reading

External links