Richard Runyan Baker
Dentist at 16 St, Phoenix, AZ

4161787, Jul 17, 1979

Nov 4, 1977

5/848558

Stanley E. Groves - Round Rock TX
Gene A. Schriber - Austin TX
Brian M. Spinks - Austin TX
Richard M. Baker - Phoenix AZ
Thomas C. Daly - Dallas TX
Rodney J. Means - Manassas VA

Motorola, Inc. - Schaumburg IL

G06F 918

364900

A programmable timer module (PTM) is provided as a component of a microprocessor system in order to generate and measure varying time intervals under program control. The programmable timer module includes, in one embodiment, three independent 16-bit timers. Each timer includes a 16-bit counter and a 16-bit latch. The programmable timer module also includes an 8-bit status register and an 8-bit control register each of which may be coupled to an 8-bit bidirectional data bus of a microprocessor system. Selection circuitry is provided which permits the microprocessor to select either the control register or the status register. Information can be written into the control register; the operation is effected by means of read/write circuitry and a read/write input. Any one of the three timers can also be selected by means of the selection circuitry, and a 16-bit number can be written into the selected 16-bit latch. Reset circuitry resets the counter whenever the 16-bit latch is written into, and the counter counts until it reaches the number written into the 16-bit latch, whereupon the interrupt circuitry generates an interrupt signal and sets an appropriate interrupt bit in the status register, and also resets that counter.