Browse Prior Art Database

Improved Poll Capture for I/O Channel

IP.com Disclosure Number: IPCOM000050601D
Original Publication Date: 1982-Nov-01
Included in the Prior Art Database: 2005-Feb-10
Document File: 2 page(s) / 41K

Publishing Venue

IBM

Related People

Bhansali, MM: AUTHOR [+4]

Abstract

The time required to perform a polling sequence for I/O devices connected to an IBM Series/1 processor I/O channel bus is substantially reduced by reducing the time period T between the issuance of the poll identification (ID) code and the issuance of the poll tag signal by the processor. This increases the I/O data rate and reduces the interrupt service time.

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Improved Poll Capture for I/O Channel

The time required to perform a polling sequence for I/O devices connected to an IBM Series/1 processor I/O channel bus is substantially reduced by reducing the time period T between the issuance of the poll identification (ID) code and the issuance of the poll tag signal by the processor. This increases the I/O data rate and reduces the interrupt service time.

Fig. 1 shows a plurality of I/O devices 1, 2 and 3 connected to a Series/1 data processor 4 by way of an I/O channel bus 5 for the processor 4. Bus 5 includes a plural line interrupt request in bus 6, a plural line poll ID bus 7, a poll tag signal line 8 and a poll return signal line 9. The poll tag line 8 is connected in a serial manner from one I/O device to the next. A device desiring interrupt service activates a particular one of the request in bus lines, the particular line depending on the interrupt priority level of the device. The processor 4 thereafter broadcasts to all of the I/O devices via the poll ID bus 7 a poll ID code, denoting the particular priority level being recognized. Shortly thereafter, the processor 4 sands out a poll signal on the poll tag line 8, which signal is propagated from one I/O device to the next until it is received by the first requesting service I/O device having a priority level which matches the priority code on the poll ID bus 7. The poll signal is captured by such I/O device, and such I/O device sends back to the processor 4 a...