Dual Use of Pins to Output Internal Machine Status Information
Original Publication Date: 1989-Oct-01
Included in the Prior Art Database: 2005-Jan-29
This article describes a method of utilizing every available external bus of a multi-chip, microcode-controlled central processing unit (CPU) to relate its internal machine state when these external buses are idle or when their basic information is not required. This can bring important information to the very large-scale integration (VLSI) designer and architects to debug, fix internal problems, real-time test and, (Image Omitted) finally, to study the behavior of the machine while running application programs. The study of the machine internal behavior is used to augment performance of future designs. All this is achieved while minimizing any impact to packaging when the chip input/output (I/O) was multi-used.