Appendix A is microfiche (five sheets containing a total of 302 frames) containing copyrighted material, Copyright 1995, National Semiconductor Corporation, consisting of a C-language code listing for a CPU design for an integrated circuit in accordance with the foregoing discussion.
1. Field of the Invention
The present invention relates to integrated circuits containing a central processing unit and a number of peripheral circuit functions, and in particular, to such integrated circuits wherein the central processing unit and peripheral circuit functions communicate both among themselves and with external circuit functions.
2. Description of the Related Art
Due to the need for backwards compatibility with older generations, the x86 is one of the most complex instruction set architecture (CISC) microprocessors. For example, the large and complex i486 has over 400 instructions that must be implemented to maintain backward compatibility with the older generation x86 processors. Such complexity has resulted in few compatible processors or controllers which are suitable, e.g. simple in design, small in size and low in cost, for use in embedded control applications. Accordingly, it would be desirable to have a processor or controller which is x86-compatible and yet suitable for low cost embedded control applications.