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Method for Improving Performance of EDX Emulator

IP.com Disclosure Number: IPCOM000042230D
Original Publication Date: 1984-May-01
Included in the Prior Art Database: 2005-Feb-03
Document File: 3 page(s) / 17K

Publishing Venue

IBM

Related People

Mansfield, SK: AUTHOR

Abstract

This method provides a new machine instruction for IBM Series/1 processors that will significantly enhance the performance of the Event Driven Executive (EDX) emulator and ultimately the Event Driven Executive (EDX) operating system for such Series/1 processors. This new instruction migrates the mapping actions of the EDX emulator into Series/1 microcode. A simplified model of the EDX software operating system for IBM Series/1 data processors and its relationship to an Event Driven Language (EDL) user program is shown in Fig. 1. EDL is a high level language in which user programs are written to run with the EDX operating system. This model is used to demonstrate graphically the basic areas of the EDX operating system activity. This operating system can be broken into three distinct areas of activity.

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Method for Improving Performance of EDX Emulator

This method provides a new machine instruction for IBM Series/1 processors that will significantly enhance the performance of the Event Driven Executive (EDX) emulator and ultimately the Event Driven Executive (EDX) operating system for such Series/1 processors. This new instruction migrates the mapping actions of the EDX emulator into Series/1 microcode. A simplified model of the EDX software operating system for IBM Series/1 data processors and its relationship to an Event Driven Language (EDL) user program is shown in Fig. 1. EDL is a high level language in which user programs are written to run with the EDX operating system. This model is used to demonstrate graphically the basic areas of the EDX operating system activity. This operating system can be broken into three distinct areas of activity. The first area is the I/O support area and includes I/O initialization, I/O drivers, and I/O interrupt routines (immediate action routines). The second area is the EDX supervisor consisting basically of the dispatcher, basic supervisor functions and supervisor call (SVC) support. The third area is the EDL emulation area and includes the EDX emulator and the mapping routine. The EDX emulator includes the individual function routines which perform the individual data processing actions called for by the different EDL instructions. The mapping routine, which is sometimes called a "command set-up" routine, fetches the EDL program instruction to be executed and the two EDL program operands which are to be the subjects of such execution. An EDL program is executed by emulating the target machine (EDL language) instructions on a host machine, in this case a Series/1 processor. A program in the host machine fetches the instructions and operands of the EDL program (mapping actions) and passes them on to the appropriate individual function routines in the emulator for execution purposes. If the I/O interrupt activity on the system is low and users are not directly or indirectly making a lot of supervisor calls, it has been found that a substantial amount of processor time is spent traversing from the mapping routine to the individual function routines in the emulator. This execution path must be taken each time an EDL instruction is emulated. Any reduction of emulation overhead would improve the performance of the emulator and ultimately that of the operating system itself. A good candidate for such an overhead reduction is the mapping routine. This mapping routine fetches each EDL program instruction and its associated operands, resolves any addressing modes used by the instruction, and generates the proper branch path to the individual function emulation routine for the instruction. The mapping routine performs no useful work for the operation under emulation other than fetching parameters and passing control to the appropriate emulator function routine. A close study of the mapping routine and...