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Monitoring an Address Range with System 370 per Feature Without Interrupts

IP.com Disclosure Number: IPCOM000085879D
Original Publication Date: 1976-Jun-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 2 page(s) / 27K

Publishing Venue

IBM

Related People

Snyder, HC: AUTHOR [+2]

Abstract

This system is for monitoring events within an address range with the IBM System/370 PER feature, without causing continuous interrupts.

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Monitoring an Address Range with System 370 per Feature Without Interrupts

This system is for monitoring events within an address range with the IBM System/370 PER feature, without causing continuous interrupts.

The PER control registers, CR10 and CR11, originally contain the low and high boundaries of an address range, respectively. Selected events happening within this range will cause interrupts for each occurrence which can happen as frequently as the number of I-fetches. This will impose an intolerable interrupt level on the system.

The method is to reverse the address boundaries with the first PER interrupt so that CR10 and CR11 now hold the high and low boundaries, respectively. Reversal of boundaries can be accomplished either through software by actually exchanging the values in CR10 and CR11, or by switching the detection circuits in System/370 from detecting inside range to detecting outside range. Although the program is still executing within the original range, to PER it appears to be outside the range and no further interrupts will occur.

A latch, which is set with the first interrupt when the contents of CR11 are greater than CR10 can be used to record time within the range, or used to monitor events within the range. When an event occurs outside the original range it will now appear to fall within the range of PER and another interrupt will occur. This second interrupt, conditioned with the fact that the value in CR11 is effectively less than the...