TheMC 14500 Industrial Control Unit (ICU) is aCMOSone-bitmicroprocessor designed byMotorola for simple control applications in 1977.[1] It was packaged in a 16-pinDIP and normally ran at 1 MHz with 5 V and only 5 μA. If higher performance was needed, it could run as fast as 4 MHz by increasing the voltage to 15 V. It was inexpensive for the era, available at launch for $7.58 in 100-unit lots.[2]
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.[3] The processor supports 16 commands, operating at a frequency of 1 MHz.[3] 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.[3]
The ICU architecture is similar to that of theDECPDP-14 computer.[citation needed][clarification needed]
The MC14500B was implemented with atransistor count of roughly 500 transistors. The chip was so simple not only because it only handled1-bit computing data at a time, but also because the chip did not include a program counter, subroutine stack, etc. -- those required external chips.[4]
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]
A form of the design served as an embedded controller in a custom automotive chip made forNippon Denso by Motorola—Japan.
I.P.R.S. Băneasa manufactured a clone of the MC14500B with the designation βP14500 inIIL technology (rather than the original CMOS).[5]
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).[6]
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.
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