Browse Prior Art Database

Secondary Receive Registers

IP.com Disclosure Number: IPCOM000036269D
Original Publication Date: 1989-Sep-01
Included in the Prior Art Database: 2005-Jan-28
Document File: 2 page(s) / 53K

Publishing Venue

IBM

Related People

Irwin, JW: AUTHOR

Abstract

A method is described wherein a consistent software model is maintained throughout a family of I/O channels where the family members are constrained by varying logic package size. The channels having the least package constraint provide higher performance and improved error recovery without change in the channel software model.

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Secondary Receive Registers

A method is described wherein a consistent software model is maintained throughout a family of I/O channels where the family members are constrained by varying logic package size. The channels having the least package constraint provide higher performance and improved error recovery without change in the channel software model.

The channel family utilizes the main processing unit (PU) as the channel processor. Each time the PU issues a start command, the channel returns exactly one incoming frame header with all accompanying status which is held static for software processing until released by the next start command.

In the most package constrained channel (Figure 1) there is a single rank of receive registers. Any additional incoming frames that are received during the holding period are discarded and a hardware Busy response is sent on the outbound link in response to the incoming frame. The next start command following the discard is rejected with a Frame Discarded bit set in the status register to aid in software recovery.

If more logic space is available (Figure 2), the hardware Busy response mechanism is deleted and one or more sets of non-software accessible secondary header and frame status registers are added. If one or more secondary registers are full when the next start command is issued, the oldest received frame header is transferred to the primary registers and the channel action depends on the type of received frame and...