Multi-tasking low-power controller having multiple program counters

A multitasking controller comprising:

• task storage means (2) for storing up to N tasks (P0,P1,P2,P3) each comprising a sequence of instructions,
• a microprocessor for processing, by time-sharing, a plurality of said N tasks, and
• data storage means (12) for storing variable data created and used by said microprocessor, characterized in that said microprocessor further comprises
• a scheduler (7) realized in hardware for controlling the use of said microprocessor by said tasks, and
• program counter storage means for storing N program counters (Pc0,Pc1,Pc2,Pc3) each for use by said scheduler (7) to control the instruction sequence of a separate one of said N tasks, said scheduler (7) selecting a different one of said program counters (Pc0,Pc1,Pc2,Pc3) when the task processed by said microprocessor is changed without requiring the transfer of data from said data storage means (12), wherein said micro processor is configurable so as to process a portion of each of X said tasks in turn, where 1<X<N, the program counter of one or more of the remaining N-X tasks being used by said microprocessor to control the instruction sequence of a sub-routine called from within said X tasks.