MC14500B (ICU) is well-suited to the implementation ofladder logic, and thus could be used to replacerelay systems andprogrammable 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 aprogram 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]
The ICU was conceived by Vern Gregory in the mid-1970s while working as an engineer in a marketing / applications group of Motorola Semiconductor Products Sector in Phoenix, Arizona, USA; Brian Dellande originated circuit and sub-routine designs, and co-wrote the manual; Ray DiSilvestro was the bench technician; Terry Malarkey provided management support.[citation needed]
In the CMOS Logic Division in Austin, Texas, USA (where it was made) Phil Smith was the chip designer; Mike Hadley provided product applications support.[citation needed]
One of the computers known to be based on this processor is the educationalWDR 1-bit computer (512 bits of RAM, LED, I/O, keyboard).[4]
A modern take, in retro style, of a computer based on this processor is thePLC14500-Nano. It is certified as Open Source HardwarePL000011 so anyone can learn from its design and can freely build it.
^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. Retrieved2017-05-20.
Gregory, Vernon "Vern" C. (1979-05-08) [1977-01-24]."Industrial control processor"(PDF).Motorola, Inc. US patent 4153942A.Archived(PDF) from the original on 2022-06-17. Retrieved2022-06-17.[2] (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
