Computer system having a DSP local bus

#The present invention relates generally to computer system architecture and, more specifically, to a computer system having a bus interface circuit that creates a digital signal processor (DSP) local bus from a peripheral bus that allows simultaneous data transfers between DSPs on the DSP local bus and between devices on the peripheral bus.

#Personal computer systems are well known in the art. Personal computer systems in general, and IBM Personal Computers in particular, have attained widespread use for providing computer power to many segments of today's modern society. Personal computers can typically be defined as a desktop, floor-standing, or portable microcomputer that is comprised of a system unit having a single central processing unit (CPU) and associated volatile and non-volatile memory, including all RAM and BIOS ROM, a system monitor, a keyboard, one or more flexible diskette drives, a fixed disk storage device, and an optional printer. One of the distinguishing characteristics of these systems is the use of a motherboard or system planar to electrically connect these components together. These systems are designed primarily to give independent computing power to a single user and are inexpensively priced for purchase by individuals or small business. Examples of such personal computer systems are IBM's PERSONAL COMPUTER AT and IBM's PERSONAL SYSTEM/2.

#In computer systems, the components communicate via electrical signals. These electrical signals are typically carried by electrical connections between the system components. Typical types of electrical connections include metal traces on a printed circuit board, vias, plated through holes, plugs, and individual wires wrapped from pin to pin of system components. Typically groups of electrical signals and groups of electrical connections that carry the electrical signals are referred to as a "bus." Thus, a reference to a "bus" can indicate a reference to a group of electrical signals, a group of electrical connections that carry the electrical signals, or a reference to both a group of electrical signals that form a protocol and a group of electrical connections that carry the electrical signals. Systems can be said to have a variety of buses. A "local bus" is a bus that is, in general, synchronous with the CPU and designed to optimize the performance of the CPU. Most systems also have a "peripheral bus," which is either synchronous or asynchronous, and may transfer data at a slower frequency than the local bus. Peripheral buses typically have a number of interface slots, which are connectors that allow peripheral device cards to be pluggably connected to the peripheral bus. Typically the peripheral bus is interfaced to the system local bus with a bus interface circuit (BIC). The BIC interfaces between the system local bus and the peripheral bus, handling any differences in bus bandwidths, managing control of the buses between busmasters, etc.

#In the accompanying drawings, which are incorporated in and constitute a part of this specification, embodiments of the invention are illustrated, which, together with a general description of the invention given above, and the detailed description given below serve to exemplify the principles of this invention.

#FIG. 1 is a block diagram of a generic prior art computer system with multiple DSPs.

#FIG. 2 is a block diagram of a computer system having a DSP local bus of the present invention.

#Before describing the details of the present invention, a description of a generic prior art computer system 10 with multiple DSPs may be helpful in understanding the advantages of the computer system 40 of the present invention. Reference is made, therefore, to FIG. 1, which shows a prior art computer system 10 with multiple DSPs. The typical prior art computer system 10 comprises a CPU 12, memory 14, and miscellaneous circuitry 16 needed to generate the address, data, control, and status signals (not shown) that make up a system local bus 18. The prior art computer system 10 further comprises a bus interface circuit 20, which generates a peripheral bus 22. The peripheral bus 22 typically has a number of expansion slots (not shown) so that various I/O devices 24 may be pluggably connected to the peripheral bus 22.

#The prior art computer system 10 also comprises a number of digital signal processors (DSPs) either attached to the system local bus 18, shown at 26a-26b, or attached to the peripheral bus 22, shown at 26c-26d. The computer system 10 may also have DSPs attached to both the system local bus 18 and the peripheral bus 22, shown at 26a-26d.

#The BIC 20 acts as an interface between the system local bus 18 and the peripheral bus 22. For example, if the CPU 12 transfers data to the I/O devices 24, the BIC 20 must change the synchronous data along the system local bus 18 to asynchronous data along the peripheral bus 22. The BIC 20 may also be required to change bandwidth between the system local bus and the peripheral bus 22. For example, the system local bus 18 may have a bandwidth of 33 Mhz and the peripheral bus 22 may have a bandwidth of 16 Mhz.