Browse Prior Art Database

Simulation of Virtual Devices

IP.com Disclosure Number: IPCOM000079834D
Original Publication Date: 1973-Sep-01
Included in the Prior Art Database: 2005-Feb-26
Document File: 2 page(s) / 46K

Publishing Venue

IBM

Related People

Hesse, AW: AUTHOR [+2]

Abstract

A computer arrangement is illustrated for producing the functions of a physical direct-access storage device, without either the device itself or a substitute device being attached to the system.

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Simulation of Virtual Devices

A computer arrangement is illustrated for producing the functions of a physical direct-access storage device, without either the device itself or a substitute device being attached to the system.

Given a single-processor system, the device simulator (DS) 10, the operating system 11, and the application program 12 will reside in the same machine. A device characteristic table 13 is established for each type of device to be simulated. The operating system is arranged to include both a channel and a device in the system definition, and a modification is made to trap Start I/O for the device into the DS area 14. The device characteristic table is thus fetched from a data set in the system and placed in area 13. The table gives DS the information concerning track length, timing element, number of tracks, etc., to be simulated.

The application program may then create and update a data set, which is actually stored in storage area 15. All input/output instructions for the device being simulated will thus be trapped and forwarded to DS.

As shown in the second figure, the DS control 16 fetches the channel commands individually, determines their command code, and simulates the responsive functions of the device by producing entries in the device status 17, track 18, or record tables 19, and by the actual transfer of data from the application program area 12 to the device simulator storage area 20.

The simulation is transparent to the system an...