Abstract: A data processor such as an integrated circuit microcontroller (10) includes a central processing unit (12), a system integration module (14), and on-chip peripherals (16, 24, 28, 30) commonly connected by an information bus (32). The microcontroller (10) supports transparent background mode operation by not only preserving the state of the central processing unit (12), but also the states of on-chip peripherals (16, 24, 28, 30). For example, a serial peripheral interface (16) has a status register (86) with some status bits which are cleared in normal mode by reading the status register (86). In background mode, reading the status register (86) does not cause the status bits to be cleared. The system integration module (14) has a control bit, known as the break clear flag enable (BCFE) bit, which selectively allows the states of the on-chip peripherals (16, 24, 28, 30) to be altered when the microcontroller is in background mode.

Abstract: Method and apparatus in a data processing system (10) for determining wait states on a per cycle basis. The present invention provides a wait state value (39) to a data processing system (10) indicating the number of wait states for each bus cycle. In one embodiment, a wait state pulse (81) is provided by data processing system (10), during which the wait state value (39) is provided to data processing system (10) by way of data bus (82). In response to the wait state value (39), data processing system (10) inserts a number of wait states corresponding to the wait state value (39) during the present bus cycle. In one embodiment of the present invention, a chip select signal (73) is combined with a portion of the address (83) to further partition the address range of the chip select signal (73).