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Browse Prior Art Database

Hardware Busy Frame Generation

IP.com Disclosure Number: IPCOM000036378D
Original Publication Date: 1989-Sep-01
Included in the Prior Art Database: 2005-Jan-29
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Irwin, JW: AUTHOR

Abstract

A method is described in which a simple serial channel generates a hardware level Busy frame in response to correctly addressed, incoming connect frames from the time the channel internally enters stopped state until the first Idle sequence is recognized after the channel accepts a subsequent Start command. The Busy response, therefore, originates when the channel is in the process of reinstruction, and not when it is actually busy performing an operation.

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Hardware Busy Frame Generation

A method is described in which a simple serial channel generates a hardware level Busy frame in response to correctly addressed, incoming connect frames from the time the channel internally enters stopped state until the first Idle sequence is recognized after the channel accepts a subsequent Start command. The Busy response, therefore, originates when the channel is in the process of reinstruction, and not when it is actually busy performing an operation.

The simple serial channel is a shallow adapter that has a single rank of receive registering and uses the main processor to perform the sequencing usually performed by a dedicated microcode engine. The channel is able to process only a single incoming frame or a related, error-free sequence of incoming frames before requiring processor service. It is also necessary for the main processor to periodically make the channel not ready in order to change the channel operation between listening and originating.

Whenever an error occurs or an incoming frame arrives that requires processing, the channel stops, posts status, and (optionally) interrupts. The main processor then interprets the channel status, sets the channel up for the appropriate operation, and issues a Start command to again make the channel responsive to the incoming link.

At the time the Start command is issued, it is possible to be at any stage of receiving a frame from the incoming link; therefore, on receipt of the St...