Abstract: An integrated circuit (IC) includes multiple circuits and functions which share multiple internal signal buses, three physical and five logical, according to distributed bus access and control arbitration. The multiple internal signal buses are shared among three tiers of internal circuit functions: a central processing unit and a DMA controller; a DRAM controller and a bus interface unit; and peripheral interface circuits, such as PCMCIA and display controllers. Two of the physical buses correspond to two of the logical buses and are used for communications within the IC. The third physical bus corresponds to three of the logical buses and is used for communications between the IC and circuits external to the IC. Arbitration for accessing and controlling the various signal buses is distributed both within and among the three tiers of internal circuit functions.

Abstract: A bidirectional parallel signal interface for providing a parallel data interface between a computer and an external peripheral device includes an interface circuit with command registers for communicating commands and data, a first-in, first-out (FIFO) memory for communicating data between the computer and the peripheral device, and host and slave state machines for receiving commands from the command registers and in accordance therewith controlling communication of data between the FIFO and peripheral device and communicating control signals to and from the peripheral device. The communication of data between the FIFO and peripheral device is effected in accordance with data communication rates which are controlled by the host and slave state machines in accordance with the commands from the command registers.