Motorola 56000

The 56k series was intended mainly for embedded systems doing signal processing, but was also quite popular for a time in a number of computers, including the NeXT, Atari Falcon030 and SGI Indigo workstations all using the 56001.

[9] 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.

[7] It uses 5 V TTL levels and consumes approximately 0.4 W.[7] In most designs the 56000 is dedicated to one single task, because digital signal processing using special hardware is mostly real-time and does not allow any interruption.

The 56000 can execute a 1024-point complex Fast Fourier transform (FFT) in 59,898 clock cycles, taking 1.8 ms at 33 MHz,[7] 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.

[10][11] The addition of SIMD 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.

Motorola XSP56001
Die of Motorola DSP56001.
Die of Motorola DSP56002.
Motherboard of the NeXTcube from 1990 having a Motorola 68040 (25 MHz) and a digital signal processor Motorola 56001 with 25 MHz which was directly accessible via an interface.