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Device Interrupt Vectoring with Control Block Addressability

IP.com Disclosure Number: IPCOM000089652D
Original Publication Date: 1977-Dec-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 28K

Publishing Venue

IBM

Related People

Davis, MI: AUTHOR [+3]

Abstract

When an interrupt mechanism provides a unique interrupt vector for each interrupting device, it is desirable to provide addressability to a control block as part of the interrupt action. This article defines a mechanism that provides addressability to a unique control block for the interrupting device and allows execution of common or unique code. It may be used in connection with various systems, such as the IBM Series/1 computers.

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Device Interrupt Vectoring with Control Block Addressability

When an interrupt mechanism provides a unique interrupt vector for each interrupting device, it is desirable to provide addressability to a control block as part of the interrupt action. This article defines a mechanism that provides addressability to a unique control block for the interrupting device and allows execution of common or unique code. It may be used in connection with various systems, such as the IBM Series/1 computers.

A device vector table (DVT) is defined at a fixed location in storage. The address (and vector) corresponding to a given device is defined by the device address (an eight-bit number) and the base address of the vector table, as shown. Storage Address Contents 30 DDB0 Device 0 Vector 32 DDB1 Device 1 Vector 34 DDB2 Device 2 Vector 36 DDB3 Device 3 Vector Storage Address Contents 38 . 3A . .
. 30 + 2N DDB N Device N Vector

Reference is made to Fig. 1. The contents of each vector location is the address of a device data block (DDB) established by system programming. The first location of the DDB contains the address of the code string to be executed when a given device interrupt occurs, also established by system programming.

The remainder of the DDB (length and content) is defined and used by system programming. The normal use is as a device control block containing control information.

Of special interest in a machine which operates as defined here is the control block structure defined, the manner in which the interrupt entry is handled, and the control block addressability provided.

When a devic...