Clockless processors, also referred to as asynchronous or self-timed chips, will help create a whole new generation of applications, thanks to their low power consumption and low levels of electromagnetic emissions.

Asynchronous CPUs basically reduce power consumption because each section of the circuit only operates when data arrives. There are no central clocks, so the switching of the transistors is not synchronized. This means electromagnetic emissions are also significantly reduced. Products often have to go through stringent emissions checks before they can be sold and asynchronous implementations may help avoid costly product modifications to meet conformance standards.

The concept of clockless processors has been hovering around in the background for some time, primarily because of their power-saving potential. Clockless 32-bit RISC processors from ARM and other companies have been created, but haven’t gone past the research stage, mainly due to difficulties with the portability and testability of the designs, making it difficult to integrate the asynchronous technology into production-capable products.

ARM has long realized the viability of asynchronous design, supporting the Amulet research group at Manchester University led by Professor Steve Furber. In fact its asynchronous Amulet3 ARM processor of the 90s got very close to commercial success through a DECT wireless basestation. This time asynchronous technologies look set to succeed.

Recently ARM and Philips’ Handshake Solutions announced a collaboration to develop a clockless processor. It will be the first general purpose asynchronous commercial processor to reach the market.

The ARM processor will utilize Handshake Solutions' Handshake Technology, which is the industry's first production proven methodology for using self-timed circuitry in commercial applications. The design will be available in the first half of 2005.

Handshake Technology has been used for more than five years in tens of millions of products including smart cards, advanced pagers, In-Vehicle Network transceivers, and cordless handsets. The compact asynchronous ARM processor is expected to appear in smart card, consumer electronics, and automotive markets because of its very low-power consumption and low Electro Magnetic Interference (EMI),

This new ARM processor will also be optimized for use in both synchronous and asynchronous system-on-chip designs, permitting easy integration by semiconductor makers.

The key benefits of the processor being touted include low Electro Magnetic emissions, reducing the probability of interfering with sensitive circuitry, reducing system power requirements and significantly extended battery life.

ARM and Handshake aren’t the only companies championing asynchronous design in the industry right now, and they undoubtedly have a head start in opening up the technological benefits to the semiconductor industry already convinced by the benefits of the ARM architecture.