Browse Prior Art Database

Channel Subsystem With Selectively Reduced Interrupts to a Processor

IP.com Disclosure Number: IPCOM000103031D
Original Publication Date: 1990-May-01
Included in the Prior Art Database: 2005-Mar-17
Document File: 1 page(s) / 50K

Publishing Venue

IBM

Related People

Brown, PJ: AUTHOR [+5]

Abstract

In some data processing systems, processors called channel processors (or channels) handle transfers of data between I/O devices and the central processor memory. A central processor starts a data transfer by first setting up a control block and then executing an instruction that gives the address of the control block. Therefore, a processor called an I/O processor (IOP) fetches the control block and performs other operations to enable one of the channels to begin the data transfer. The IOP and the channel share a control block that has information about the device. At the end of the data transfer, the channel interrupts the IOP and presents final status. The IOP then transfers information to the central processor to report that the data transfer has been completed.

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Channel Subsystem With Selectively Reduced Interrupts to a Processor

      In some data processing systems, processors called channel
processors (or channels) handle transfers of data between I/O devices
and the central processor memory.  A central processor starts a data
transfer by first setting up a control block and then executing an
instruction that gives the address of the control block.  Therefore,
a processor called an I/O processor (IOP) fetches the control block
and performs other operations to enable one of the channels to begin
the data transfer.  The IOP and the channel share a control block
that has information about the device.  At the end of the data
transfer, the channel interrupts the IOP and presents final status.
The IOP then transfers information to the central processor to report
that the data transfer has been completed.

      Conventionally, the channel also interrupts the IOP and
presents initial status after the channel has completed the
preliminary operations for the data transfer.  The IOP also transfers
information to the central processor when it receives initial status
and a bit "Initial Status Requested" is set in the control block.

      In a new system, the IOP selectively inhibits the interruption
for initial status by setting a bit in the shared control block.  A
channel is adapted to check the bit and to present initial status
only when the bit is set. When the IOP has inhibited the interruption
for initial status, th...