[ii] 4,360,870  Nov. 23, 1982
 PROGRAMMABLE I/O DEVICE IDENTIFICATION
 Inventor: James M. McVey, Leander, Tex.
 Assignee: International Business Machines Corporation, Armonk, N.Y.
 Appl. No.: 173,585
 Filed: Jul. 30, 1980
 Int. CU G06F9/06
 U.S. CI 364/200
 Field of Search ... 364/200 MS File, 900 MS File
 References Cited
U.S. PATENT DOCUMENTS
3,680,052 7/1972 Arulpragasam et al 364/200
3,828,325 8/1974 Stafford et al 364/200
3,909,790 9/1975 Shapiro et al 364/200
4,079,452 3/1978 Larson et al 364/900
IBM Technical Disclosure Bulletin vol. 22, No. 3, Aug. 1979, "Programmable Identification for I/O Devices", J. M. McVey, pp. 882 and 883.
A computer system having a CPU connected to I/O devices via a channel sets addresses into the I/O devices by the CPU. The I/O devices, for purposes of control, are grouped in types. To load device addresses or identifiers, the processor sends a type identifier to the I/O devices. The device having the highest ordered priority of the same type of device and which does not have an assigned identifier responds by inhibiting all lower ordered devices of its type. It is then loaded with its unique assigned identifier which results in the setting of a status latch therein. This setting allows the next lowest ordered device of the same type of devices to then be assigned and loaded with an identifier by the processor. This process continues until all I/O devices of the same type are loaded with identifiers. The process is then repeated for each other type of I/O devices in the system.
18 Claims, 4 Drawing Figures