  One of the main, long-term objectives of artificial intelligence is the
creation of thinking machines. To that end, substantial effort has been placed
into designing cognitive systems; i.e. systems that can manipulate
semantic-level information. A substantial part of that effort is oriented
towards designing the mathematical machinery underlying cognition in a way that
is very efficiently implementable in hardware. In this work we propose a
'semi-holographic' representation system that can be implemented in hardware
using only multiplexing and addition operations, thus avoiding the need for
expensive multiplication. The resulting architecture can be readily constructed
by recycling standard microprocessor elements and is capable of performing two
key mathematical operations frequently used in cognition, superposition and
binding, within a budget of below 6 pJ for 64- bit operands. Our proposed
'cognitive processing unit' (CoPU) is intended as just one (albeit crucial)
part of much larger cognitive systems where artificial neural networks of all
kinds and associative memories work in concord to give rise to intelligence.
