Browse Prior Art Database

Channel Monitor

IP.com Disclosure Number: IPCOM000077842D
Original Publication Date: 1972-Sep-01
Included in the Prior Art Database: 2005-Feb-25
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Tabke, RB: AUTHOR

Abstract

The described monitor provides the data necessary to do computer performance studies, based on a complete trace of the activity of the direct-access storage components of a computer installation. A hardware tracer can capture memory addresses including the origins of commands and the destination of data transfer; the memory protection key used; commands seen only by the channel; commands rejected by the channel; and channel status at the end of an I/O operation. The ability to gather the complete set of channel information, is due to its attachment to the computer for the monitoring function. To effect this attachment, the monitor is simply inserted onto the storage busses in series with the channels.

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Channel Monitor

The described monitor provides the data necessary to do computer performance studies, based on a complete trace of the activity of the direct- access storage components of a computer installation. A hardware tracer can capture memory addresses including the origins of commands and the destination of data transfer; the memory protection key used; commands seen only by the channel; commands rejected by the channel; and channel status at the end of an I/O operation. The ability to gather the complete set of channel information, is due to its attachment to the computer for the monitoring function. To effect this attachment, the monitor is simply inserted onto the storage busses in series with the channels.

In addition, attachment of the monitor requires four probes into the logic of the 2860 channel. The four probes used are: Probe 1: Channel Address Word and Unit Address

Probe 2: Channel Command Word

Probe 3: Data

Probe 4: Channel Status Word and Unit Address.

All items above except probe 3 are well known. The Data probe in the current context, is the data transferred from memory following certain command types. These types are variable in the hardware, an example being the Seek Command. The data written from memory following this command, is the Seek Address and is recorded as data by the monitor.

When indicated by a probe, the hardware records the full eight-byte width of the system's storage bus in an appropriate format which uniquely identifies each item on th...