Microprocessor breakpoint apparatus

Abstract

A breakpoint apparatus incorporated in a single chip microprocessor. The apparatus permits breakpoints on specific references to either program instructions or data. The width of the breakpoint address can be varied, the apparatus includes a logic circuit for determining if the reference represented by the breakpoint address overlaps the current virtual address.

Description

BACKGROUND OF THE INVENTION1. Field of the InventionThe invention relates to the field of hardware implemented breakpoints for computer programs, primarily used for analyzing or "debugging" programs.2. Prior ArtNumerous techniques are used to analyze the performance of computer programs, particularly during their development. This is often referred to as "debugging". The debugging process is recognized as a significant part of the development of a computer program, and in some cases, the time required for debugging exceeds that required to write the program.One technique used for debugging computer programs is to interrupt the program at predetermined events and then examine, for instance, the contents of registers. One such event is the generation of predetermined addresses which may be references to the computer program or data. When the address generated by the computer matches one of the predetermined addresses, a "breakpoint" occurs. The operation of the computer is interrupted...

AI Technical Summary

Benefits of technology

The present invention provides a breakpoint signal apparatus useful in debugging computer programs. The apparatus is particularly useful in an integrated circuit microprocessor formed on a single substrate which includes address generation means for generating virtual addresses for reference to program instructions or data, a virtual address bus, address translation means for converting the virtual address on the bus to a physical address, interpretation means for interpreting the program instructions, and arithmetic means for operating upon the data in accordance with the interpreted instructions. The apparatus includes a first register for storing a predetermined address in the form of a virtual address at which a breakpoint is to occur. A second register is used for storing control bits which permit the user to select certain conditions of the breakpoint such as whether the breakpoint is to occur at a reference to computer program or data. a comparator means compares the

Problems solved by technology

This method is relatively inexpensive, however, it has the disadvantage that breakpoints cannot be set for address references to data.

This method is generally expensive and requires a significant amount of printed circuit board space.

Moreover, for high speed processors it does not react quickly enough to provide a "real time" breakpoint.

A significant problem arises where microprocessor includes an address translation unit such as a memory management unit on the microprocessor itself.

That is, virtual addresses used by the programmer may not be available.

It is difficult to set breakpoints based on physical addresses.

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