CPU and Support Processor Communication Mechanism
Original Publication Date: 1984-Mar-01
Included in the Prior Art Database: 2005-Feb-03
In a data processing system that includes a primary CPU and a support processor, various communications between the primary CPU and support processor are needed for functions such as diagnose instruction and display storage data, etc. A low cost and simple mechanism employing an 8-byte register is used to transfer commands and data between the processors. The 8-byte register can be sourced or destined via decodes in the BRANCH microword on the primary CPU and can be scanned by the support processor without stopping the primary CPU clocks. Along with the 8-byte register, interrupts and response latches are provided on both processors for handshaking. They insure that the register is not being scanned when the CPU is trying to reference it.