AMD has agreed to invest $7.5m in microprocessor developer Transmeta to support the firm's development of energy efficient chip technologies. 

AMD will receive preferred Transmeta stock for its investment, but other terms of the transaction were not disclosed.

Transmeta and AMD have a history of collaboration. Transmeta provided AMD with the HyperTransport bus and AMD64 technology that have been instrumental in the rise of AMD's Opteron.

AMD64 allows a single processor to execute 32-bit and 64-bit instructions, enabling a smooth transition to 64-bit applications. HyperTransport allows for faster and more energy efficient data transfer rates within a processor.

Transmeta is best known for its low-power processors and the LongRun1 and LongRun2 power management technologies.

After its Crusoe notebook processor failed to take off with notebook manufacturers, Transmeta shifted course in 2005 to license its intellectual property to companies including Sony. 

Transmeta and AMD share a common enemy in Intel, both having ongoing litigation against the world's largest chip maker.

AMD accuses Intel of antitrust violations, while Transmeta has been involved in a series of patent disputes over chip architecture and power-efficiency technologies.