Browse Prior Art Database

Early Interrupt for Disk Controller

IP.com Disclosure Number: IPCOM000045182D
Original Publication Date: 1983-Feb-01
Included in the Prior Art Database: 2005-Feb-06
Document File: 2 page(s) / 21K

Publishing Venue

IBM

Related People

Brooks, WJ: AUTHOR [+4]

Abstract

The figure shows the timing diagrams for a disk controller which execute single sector operations to a disk where the data sectors are interleaved. The operation shown is a read from data sectors 2 and 3. The disk controller hardware compares sector identifiers from the disk with the one requested until a match is found and then transfers the data. When the data transfer is complete, the next sector pulse terminates the operation and raises an interrupt to the processor. The processor handles the interrupt, processes status, and issues commands to the hardware to transfer the next data sector.

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Early Interrupt for Disk Controller

The figure shows the timing diagrams for a disk controller which execute single sector operations to a disk where the data sectors are interleaved. The operation shown is a read from data sectors 2 and 3. The disk controller hardware compares sector identifiers from the disk with the one requested until a match is found and then transfers the data. When the data transfer is complete, the next sector pulse terminates the operation and raises an interrupt to the processor. The processor handles the interrupt, processes status, and issues commands to the hardware to transfer the next data sector.

The interrupt processing window is from the sector pulse which terminates the data transfer until the sector pulse which starts the next data transfer. This window can be increased in size if the hardware raises the interrupt after a successful identifier comparison. This early warning interrupt signals the processor that the hardware will complete the data transfer within a given time. The processor now has an additional time to handle the interrupt, initiate processing, and then wait until the hardware drops busy before processing the status and issuing the next command.

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