Motorola MC14500B

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1-bit microprocessor MC14500BCP

The MC14500B Industrial Control Unit (ICU) is a CMOS one-bit microprocessor designed by Motorola for simple control applications in 1977.[1] It is well-suited to the implementation of ladder logic, and thus could be used to replace relay systems and programmable logic controllers, also intended for serial data manipulation.[2] The processor supports 16 commands, operating at a frequency of 1 MHz.[2] The MC14500B unit does not include a program counter (PC); instead, a clock signal drives a separate PC chip; therefore the size of supported memory is dependent on the implementation of that chip. It was still in production in 1995.[2]

One of the computers known to be based on this processor is the educational WDR 1-bit computer (512 bits of RAM, LED, I/O, keyboard).[3]

The ICU architecture is similar to that of the DEC PDP-14 computer.

See also[edit]


  1. ^ Gregory, Vernon C.; Dellande, Brian; DiSilvestro, Ray; Malarkey, Terry; Smith, Phil; Hadley, Mike (1977). Motorola MC14500B Industrial Control Unit Handbook - Theory and Operation of a CMOS one-bit processor compatible with B series CMOS devices (PDF). Motorola Semiconductor Products Inc. 33-B78/8.0. Retrieved 2017-05-20.  (NB. Also available in German language under the title "Motorola MC14500B Industrial Control Unit Handbuch - Theorie und Anwendung eines Ein-Bit-CMOS-Prozessors".)
  2. ^ a b c Industrial Control Unit MC14500B (PDF). Motorola CMOS Logic Data. Semiconductor Technical Data (revision 3 ed.). Motorola. 1995. pp. 306–313. Archived (PDF) from the original on 2017-05-20. Retrieved 2012-08-01. 
  3. ^ Ludwig, Volker; Paschenda, Klaus; Schepers, Heinz; Terglane, Hermann-Josef; Grannemann, Klaus; John, Burkhard; Komar, Hermann; Meinersen, Ludwig (1986). Written at Neuss & Recklinghausen, Germany. Fast alles über den WDR-1-Bit-Computer (PDF) (in German). Neuss, Germany: DATANorf. Archived (PDF) from the original on 2017-05-20. Retrieved 2017-05-20. 

Further reading[edit]

  • US patent 4153942A, Vernon C. Gregory, "Industrial control processor", published 1979-05-08, assigned to Motorola, Inc.  (also: US 05/761,738; DE2801853A1)
  • Ludwig, Volker; Paschenda, Klaus, Remmelmann, Alexander, ed., Bit und Byte - Wir bauen einen Computer [Bit and Byte - We build a computer] (TV series (6 parts)) (in German), WDR-Schulfernsehen 
  • Mueller, Dieter (2008). "MC14500 and arithmetic". Archived from the original on 2017-05-20. Retrieved 2017-05-20. 

External links[edit]