A.C.A.B. (All Clocks Are Boring)

Without moving a muscle…
…unless it’s strictly necessary! More than 10 years ago, back in 2004, Philips’ Handshake Solutions introduced an asynchronous version of the mighty 8051 (more specifically a fully-compatible clockless 80C51). This picture shows photon emission images captured from a clocked, standard 8051 MCU (left), and its clock-free relative, the HT80C51 (right), executing the same program. The red dots indicate the level and distribution of power dissipation. The asynchronous MCU uses the modules of the chip needed only, the rest consumes literally zero power.
HT80C51 asynchronous MCU
© Handshake Solutions / Koninklijke Philips Electronics N.V.
A real potato chip
It’s well known that clockless chips can run faster and much more efficiently than their synchronous counterparts. In fact, as long ago as 1989, engineer Mika Nyström from the Asynchronous VLSI group at the California Institute of Technology demonstrated how their CAM (Caltech Asynchronous Microprocessor), the world’s first async MCU, could run at around 300 kHz, with a quite peculiar power supply: Two potatoes connected in series (creating about 0.9 V).
Caltech Asynchronous Microprocessor
© Asynchronous VLSI Group, Caltech
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