Editing Motorola 56000

{{Short description|Family of digital signal processors}}
[[Image:KL Motorola DSP XSP56001ZL.jpg|right|thumb|200px|Motorola XSP56001]]
The '''Motorola DSP56000''' (also known as '''56K''') is a family of [[digital signal processor]] (DSP) chips produced by [[Motorola]] Semiconductor (later [[Freescale Semiconductor]] and then [[NXP Semiconductors|NXP]]) starting in 1986<ref>[https://ieeexplore.ieee.org/xpl/articleDetails.jsp?reload=true&tp=&arnumber=4089744&contentType=Journals+%26+Magazines&sortType%3Dasc_p_Sequence%26filter%3DAND(p_IS_Number%3A4089732)%26rowsPerPage%3D50 The Motorola DSP56000 Digital Signal Processor] IEEE</ref><ref>[http://cache.freescale.com/files/dsp/doc/inactive/DSP56000UM.pdf freescale.com – DSP56000 24-BIT DIGITAL SIGNAL PROCESSOR FAMILY MANUAL] ([https://web.archive.org/web/20190119121433/http://cache.freescale.com/files/dsp/doc/inactive/DSP56000UM.pdf archived 2019])</ref><ref>[http://www.nextcomputers.org/NeXTfiles/Docs/Audio/DSP56001/APR3.pdf Fractional and Integer Arithmetic using the DSP56000 Family]</ref><ref>[http://homes.esat.kuleuven.be/~iverbauw/Reading/EAL_DSPI.pdf  Programmable DSP architectures]</ref><ref>[http://ppd.fnal.gov/experiments/e907/TPC/DAQ/56KCCUM.pdf Motorola DSP56000 Family Optimizing C Compiler User's Manual]</ref> with later models still being produced in the 2020s. The 56k series was intended mainly for signal processing in embedded systems, but was also used in a number of early computers, including the [[NeXT Computer|NeXT]], [[Atari Falcon|Atari Falcon030]] and [[SGI Indigo]] [[computer workstation|workstation]]s, all using the 56001.<!--page_13--><ref>[http://dev-docs.atariforge.org/files/Falcon030_Schematic.pdf atariforge.org – Atari Falcon030 Schematic Rev A] {{Webarchive|url=https://web.archive.org/web/20150724085941/http://dev-docs.atariforge.org/files/Falcon030_Schematic.pdf |date=2015-07-24 }}, 1992-06-28</ref> Upgraded 56k versions are still used {{As of|2004|alt=today}} in audio equipment, [[radar]] systems, communications devices (like [[mobile phone]]s) and various other [[embedded system|embedded]] DSP applications. The 56000 was also used as the basis for the updated [[Motorola 96000|96000]], which was not commercially successful.

== Technical description ==
[[File:Motorola DSP56001 die.JPG|thumb|180px|[[Die (integrated circuit)|Die]] of Motorola DSP56001.]]
The DSP56000 uses [[fixed-point arithmetic]], with 24-[[bit]] program [[Word (data type)|word]]s and [[24-bit]] data words. It includes two 24-bit [[processor register|registers]], which can also be referred to as a single 48-bit register. It also includes two 56-bit [[Accumulator (computing)|accumulator]]s, 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]] processor, the 56k has three [[Memory space (computational resource)|memory space]]s+[[computer bus|buses]] (and on-chip memory banks in some of the models): a program memory space/bus and two data memory space/bus.<!--page_3--><ref name=fs561a/> The stack area is allocated in a separate address space, which is called "Stack Memory Space",<ref>{{cite web |url=http://cache.freescale.com/files/dsp/doc/inactive/DSP56000UM.pdf |archive-url=https://web.archive.org/web/20190119121433/http://cache.freescale.com/files/dsp/doc/inactive/DSP56000UM.pdf#page=91 |archive-date=2019-01-19 |title=DSP56000 24-BIT DIGITAL SIGNAL PROCESSOR FAMILY MANUAL |page=91(5–15) |accessdate=2023-12-26}}</ref> distinct from the main memory address space.<ref name="dsp56k-ss">{{cite web |url=http://cache.freescale.com/files/dsp/doc/inactive/DSP56000UM.pdf |archive-url=https://web.archive.org/web/20190119121433/http://cache.freescale.com/files/dsp/doc/inactive/DSP56000UM.pdf#page=29 |archive-date=2019-01-19 |title=DSP56000 24-BIT DIGITAL SIGNAL PROCESSOR FAMILY MANUAL |page=29(2–5) |accessdate=2023-12-26}}</ref> The stack, which is used when subroutine calls and "long [[interrupt]]"s, is fifteen in depth.<ref name="dsp56k-ss"/>

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.{{citation needed|date=July 2017}} 24 bits correspond to a [[dynamic range]] of 144&nbsp;[[Decibel|dB]], sufficient in the 1980s when [[analog-to-digital converter]]s (ADCs) and [[digital-to-analog converter]]s (DACs) rarely exceeded 20 bits. One example is [[Asymmetric Digital Subscriber Line|ADSL]] applications, where filters typically require 20 bits of accuracy. The leftmost four bits are typically considered ample headroom to avoid overflow in calculations.

The processor is capable of carrying out 16.5 million instructions per second (MIPS) at the maximum specified clock speed of 33&nbsp;MHz<!--page_3-->,<ref name=fs561a/> and has hardware support for block-[[floating point]] [[Fast Fourier transform|FFT]].<!--page_3--><ref name=fs561a/> It uses 5&nbsp;V [[Transistor–transistor logic|TTL]] levels and consumes approximately 0.4&nbsp;W.<!--page_21--><ref name=fs561a/>

== Applications and variants ==
[[File:Motorola DSP56002 die.JPG|thumb|180px|[[Die (integrated circuit)|Die]] of Motorola DSP56002.]]
[[File:NeXTcube motherboard.jpg|thumb|upright|[[Motherboard]] of a [[NeXTcube]] from 1990 featuring the [[Motorola 68040]] [[CPU]] and Motorola DSP56001 digital signal processor.]]
In most designs the 56000 is dedicated to one single task, because digital signal processing using special hardware is mostly [[real-time computing|real-time]] and does not allow any [[interrupt]]ion. For less demanding tasks which are not time-critical, designers normally use a separate [[central processing unit|CPU]] or [[microcontroller|MCU]].

The 56000 can execute a 1024-point complex [[Fast Fourier transform]] (FFT) in 59,898 clock cycles, taking 1.8&nbsp;ms at 33&nbsp;MHz,<!--page_3--><ref name=fs561a>[http://cache.freescale.com/files/dsp/doc/inactive/DSP56001A.pdf freescale.com – Product Preview, 24-BIT DIGITAL SIGNAL PROCESSOR, DSP56001A], 1997 ([https://web.archive.org/web/20190209123945/http://cache.freescale.com/files/dsp/doc/inactive/DSP56001A.pdf archived 2019])</ref> 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.<ref>{{cite web|title=How MP3 Works: Inside the Codec|url=http://oreilly.com/catalog/mp3/chapter/ch02.html|work=MP3: The Definitive Guide|publisher=O'Reilly|accessdate=16 April 2013|author=Scot Hacker}}</ref><ref>{{cite web|title=Development of MP3|url=http://guide-for-mp3.blogspot.co.uk/|work=Guide for MP3 blog|accessdate=16 April 2013|author=Mike Adana}}</ref>

The addition of [[SIMD]] instructions to most desktop computer [[central processing unit|CPU]]s 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 [[Microcontroller|MCU]] which created a single-chip "DSPcontroller" solution, while the opposite occurred in the 68456, a [[Motorola 68000|68000]] with a 56000 on it.

A still quite prevalent model of the 56000 is the third generation '''56300''' family, starting with the 56301,<ref>{{cite web|author=Motorola|date=October 1999|title=56301 SPEC|url=http://198ic.com/pdf_info/pdf_file/d/47949.pdf|url-status=live|archive-url=https://web.archive.org/web/20200815072540/http://198ic.com/pdf_info/pdf_file/d/47949.pdf|archive-date=15 August 2020|accessdate=7 August 2020|work=128IC|id=DSP56301P/D}}</ref> which features several models with special applications hard- and firmware built-in, like [[Peripheral Component Interconnect|PCI]] interface logic, [[cyclic redundancy check|CRC]] processors, or audio [[companding|companders]]. Core clock frequencies ranged up to 250&nbsp;MHz.<ref>''DSP56K Family Overview'', p. 45 ff in [https://web.archive.org/web/20190821072341/https://www.nxp.com/docs/en/brochure/BYNDDSPBRO.pdf ''Beyond DSPs, November 2010''] (freescale/NXP).</ref>

The 56000 provides a comprehensive suite of [[development tool]], including a [[C (programming language)|C]] [[Compiler]], an [[Assembly_language#Assembler|Assembler]], and an [[Instruction set simulator]].<ref>{{cite web |url=https://www.nxp.com/docs/en/user-guide/56KCCUM.pdf |title=Motorola DSP56000 Family Optimizing C Compiler User's Manual, Release 6.3 |accessdate=2023-11-10 }}</ref><ref>{{cite web |url=https://instrumentation.obs.carnegiescience.edu/ccd/tools/DSPASMRM.pdf |title=MOTOROLA DSP ASSEMBLER REFERENCE MANUAL |accessdate=2023-11-12}}</ref><ref>{{cite web |url=http://www.bitsavers.org/components/motorola/56000/1995_Motorola_DSP_Simulator_Reference_Manual.pdf |title=MOTOROLA DSP SIMULATOR REFERENCE MANUAL |accessdate=2023-11-12}}</ref>

== References ==
{{Reflist}}

== Further reading ==
; 56000 family
* [https://archive.org/details/bitsavers_motorola56_2161396/ DSP56000 Family Manual] – Motorola
* [https://archive.org/details/bitsavers_motorola566001UsersManual_21817285/ DSP56000 / DSP56001 Users Manual] – Motorola
* [https://archive.org/details/bitsavers_motorola56sManual_26370280/ DSP56002 Users Manual] – Motorola
* [https://archive.org/details/bitsavers_motorola56sManual_32946507/ DSP56166 Users Manual] – Motorola
; 56300 family
* [https://web.archive.org/web/20220622023619/https://www.nxp.com/docs/en/reference-manual/DSP56300FM.pdf DSP56300 Family Manual] – NXP
* [https://web.archive.org/web/20190824000001/https://www.nxp.com/docs/en/data-sheet/DSP56301DS.pdf DSP56301 Datasheet] – NXP
* [https://web.archive.org/web/20220621033326/https://www.nxp.com/docs/en/data-sheet/DSP56309.pdf DSP56309 Datasheet] – NXP
* [https://web.archive.org/web/20220622023227/https://www.nxp.com/docs/en/data-sheet/DSP56374.pdf DSP56374 Datasheet] – NXP

== External links ==
* [http://www.freescale.com/webapp/sps/site/homepage.jsp?nodeId=012795&tid=FSH Freescale Digital Signal Processors]
* [http://www.zdomain.com/a56.html A56] freeware [[assembly language|assembler]] for the 56000 architecture
* [http://www.nxp.com/about/about-nxp/technology-leadership/product-longevity/product-longevity-nxp-formerly-freescale-products:FSL-PRODUCT-LONGEVITY Product-Longevity Program]

{{Motorola DSPs}}
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[[Category:Digital signal processors]]
[[Category:Freescale Semiconductor]]
[[Category:Motorola products|56000]]
[[Category:24-bit microprocessors]]