Performance Improvement Using an EMULATION Control Block
Original Publication Date: 1988-Mar-01
Included in the Prior Art Database: 2005-Feb-14
A single microprocessor that directly executes a rich subset of System/ 370 instructions such as u370 can "call" itself to emulate the instructions not executed directly on chip. Heretofore, the method of calling itself to emulate instruction has been via a program PSW swap in control store. The control store program check interrupt handler would then back up the instruction address form the OLD PSW and essentially build the fields of the Emulation Control Block below using various built in control mode diagnosis and on chip S/370 instructions of u370. A method to greatly improve system performance is as follows: - When u370 recognizes that it has decided an instruction that requires emulation, it does not do a control space program PSW swap but, instead, updates the Emulation Control Block below.