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Parallel Processing of Commands of a Single I/O Command Chain

IP.com Disclosure Number: IPCOM000088700D
Original Publication Date: 1977-Jul-01
Included in the Prior Art Database: 2005-Mar-04
Document File: 2 page(s) / 14K

Publishing Venue

IBM

Related People

Schick, T: AUTHOR

Abstract

Today, processors execute I/0 commands in sequence. Multiple sequences may be executed in parallel but they need to be unrelated from the view of the I/O command sequences. The arithmetic-and-logical instruction sequences need to be aware of any interrelationships between I/O command sequences. This article describes a technique which permits I/O command sequences to perform in parallel according to decisions made within the I/O command sequences without interrupting or interfering with the driving processor's operations.

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Parallel Processing of Commands of a Single I/O Command Chain

Today, processors execute I/0 commands in sequence. Multiple sequences may be executed in parallel but they need to be unrelated from the view of the I/O command sequences. The arithmetic-and-logical instruction sequences need to be aware of any interrelationships between I/O command sequences. This article describes a technique which permits I/O command sequences to perform in parallel according to decisions made within the I/O command sequences without interrupting or interfering with the driving processor's operations.

In a satellite transmission network, for example, ground stations are connected to several other ground stations simultaneously which is similar in characteristic to multi-drop lines. Each ground station must receive all data from the satellite link and choose which data is intended for it. Without the facility disclosed herein, all the data of a transmission block is received before the address of the block may be examined to potentially terminate the read. With the facility disclosed, the address of a transmission block may be examined in parallel with receipt of the block, and if the block is not intended for any particular ground station, then it may terminate further transfer of data for that block. Note, this may be accomplished with today's architectures, but it requires interference with the driving processor and is much less efficient.

The described technique permits multiple I/O commands to be processed in parallel for several lines but also in parallel for a given line. This is accomplished via the use of the Parallel Process (PAP) field of the command control field.

A command, e.g., Command M, containing a positive PAP condition indicates that an I/O command chain is to be processed while the m/TH/ command is being processed. The first command of the parallel command chain is located ~in contiguous memory with the m/TH/ command.

This definition permits processing of incoming data while a command is being processed without interrupting the control program or interrupting data transfer. This is important for I/O control commands such that, for example, address and sequence count processing may be executed in parallel...