Browse Prior Art Database

ID Command for Multiple Device I/O Controllers

IP.com Disclosure Number: IPCOM000042833D
Original Publication Date: 1984-Jun-01
Included in the Prior Art Database: 2005-Feb-04
Document File: 3 page(s) / 51K

Publishing Venue

IBM

Related People

Baker, ED: AUTHOR [+4]

Abstract

An input/output (I/O) command is described for enabling a host processor to obtain complete device identification (ID) information from an I/O controller having multiple and dissimilar I/O devices connected thereto. Existing multiple device I/O controllers typically return insufficient device ID information to the host processor. The new I/O command described herein eliminates additional time and checking routines by presenting specific device class and device characteristic information that reflects the actual system configuration for a multiple device I/O controller. Considering the specific example of IBM Series/1 data processing systems, there are available for such systems multiple device I/O controllers having the capability of controlling multiple I/O devices which are distinctly different in nature.

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ID Command for Multiple Device I/O Controllers

An input/output (I/O) command is described for enabling a host processor to obtain complete device identification (ID) information from an I/O controller having multiple and dissimilar I/O devices connected thereto. Existing multiple device I/O controllers typically return insufficient device ID information to the host processor. The new I/O command described herein eliminates additional time and checking routines by presenting specific device class and device characteristic information that reflects the actual system configuration for a multiple device I/O controller. Considering the specific example of IBM Series/1 data processing systems, there are available for such systems multiple device I/O controllers having the capability of controlling multiple I/O devices which are distinctly different in nature. Typical dissimilar devices which may be connected to a single I/O controller include two or more of the following: a printer, a diskette unit, a hard disk unit, a display terminal, a magnetic tape unit and a communication port. Heretofore, a problem arose because the I/O controller would present a single ID code to the programming or diagnostic system in the host processor regardless of the quantity or the type of I/O devices actually attached to the controller. This single ID code causes a tremendous burden on the initialization user program because sufficient information on the actual system configuration is not available to such program. This lack of configuration information forces the user program to use a trial and error approach to investigate the actual system configuration. This is very time-consuming and very inefficient. This problem is overcome for the case of IBM Series/1 processors by providing a new I/O command, which is called a Cycle Steal Controller Device ID (CSCDID) command. This command is for use by multiple device I/O controllers and solicits for the user software program in the host processor complete information on all the different I/O devices...