High performance microprocessor having variable speed system clock

Abstract

A high performance, low cost microprocessor system having a variable speed system clock is disclosed herein. The microprocessor system includes an integrated circuit having a central processing unit and a ring oscillator variable speed system clock for clocking the microprocessor. The central processing unit and ring oscillator variable speed system clock each include a plurality of electronic devices of like type, which allows the central processing unit to operate at a variable processing frequency dependent upon a variable speed of the ring oscillator variable speed system clock. The microprocessor system may also include an input/output interface connected to exchange coupling control signals, address and data with the central processing unit. The input/output interface is independently clocked by a second clock connected thereto.

Microprocessor with repeat instruction

Abstract

A system for real-time digital signal processing employs a single-chip microcomputer device having separate on-chip program and data memory, with separate address and data paths for program and data. An external program address bus allows off-chip program fetch in an expansion mode, with the opcode returned by an external data bus. A bus interchange module allows transfer between the separate internal program and data busses in special circumstances. A multiplier circuit produces a single state multiply function separate from the ALU. One input to the ALU passes through a full-width shifter with sign extension. The on-chip program memory is a RAM which may be configured as either program or data memory space. The processor may operate will all off-chip program memory and a large on-chip data memory, or with program execution from on-chip RAM (downloaded from the off-chip program memory) using a block move instruction. A repeat instruction is used to save program space when using block-move, or when using multiply instructions as needed for digital filters or the like.