Browse Prior Art Database

Interrupt System Expander for Computer

IP.com Disclosure Number: IPCOM000076215D
Original Publication Date: 1972-Jan-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 2 page(s) / 28K

Publishing Venue

IBM

Related People

Duvalsaint, JJ: AUTHOR [+2]

Abstract

Interrupts are caused by a request from an input/output (I/O device) for service or by termination of an I/O operation. This expander enables an interrupt from an I/O device to occur on any of 512 interrupt lines and on one of four levels of priority.

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Interrupt System Expander for Computer

Interrupts are caused by a request from an input/output (I/O device) for service or by termination of an I/O operation. This expander enables an interrupt from an I/O device to occur on any of 512 interrupt lines and on one of four levels of priority.

A single interrupt channel 1 controls up to four interrupt buffers 2-5. Channel 1 decodes the commands received from the computer 6 and provides the required control lines to buffers 2-5. It also establishes a priority scheme to determine the requesting one of the I/O devices 7. Additionally, channel 1 controls the read bus and gates it to an off condition any time an interrupt level status word or a device status word is to be read from a buffer into computer 6.

The interrupt buffers 2-5 expand the interrupt levels from the I/O devices to an 8-bit interrupt level status word. Each such bit is further expanded to a 16-bit device status word. Each of these I/O devices is assigned four of these device status word bits on each level of priority. In this way, the total of 512 interrupt bits are provided on the priority levels determined by buffers 2-5.

Each interrupt buffer accommodates eight I/O devices. Each of the I/O devices employs 16-bits for 128 interrupts on each interrupt buffer. The device status word provided by an interrupt buffer indicates which one or more of the devices has requested an interrupt. If more than one device has requested an interrupt, priority among the...