Browse Prior Art Database

MICRO Channel Slave Streaming Data Request Generation

IP.com Disclosure Number: IPCOM000108806D
Original Publication Date: 1992-Jun-01
Included in the Prior Art Database: 2005-Mar-22
Document File: 3 page(s) / 98K

Publishing Venue

IBM

Related People

Arimilli, RK: AUTHOR [+3]

Abstract

This article describes a structure to allow MICRO CHANNEL* slaves to easily implement the Streaming Data Request logic, -SDR(0). The -SDR(0) indicates the ability of a slave to participate in the higher Streaming Data protocol. The Input/Output Channel Controller (IOCC) of the IBM RISC System/6000* (RS/6000) systems implemented this structure in order to minimize logic, meet critical MICRO CHANNEL timings and provide optimal MICRO CHANNEL compatibility.

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MICRO Channel Slave Streaming Data Request Generation

       This article describes a structure to allow MICRO
CHANNEL* slaves to easily implement the Streaming Data Request logic,
-SDR(0).  The -SDR(0) indicates the ability of a slave to participate
in the higher Streaming Data protocol.  The Input/Output Channel
Controller (IOCC) of the IBM RISC System/6000* (RS/6000) systems
implemented this structure in order to minimize logic, meet critical
MICRO CHANNEL timings and provide optimal MICRO CHANNEL
compatibility.

      During Bus Master DMA, the RS/6000 IOCC acts as a MICRO CHANNEL
memory slave for transfers with system memory.  The IOCC can request
the higher performance Streaming Data protocol by activating -SDR(0)
low. Once Streaming Data transfers begin, the IOCC or the Bus Master
can terminate the protocol.  The slave indicates a desire to
terminate by deactivating -SDR(0) high.  This mechanism is used to
obtain high performance by supporting the Streaming Data protocol, as
well as pace the protocol via termination.

      The design challenges associated with this task include
critical MICRO CHANNEL timings both during entry into the Streaming
Data protocol and during slave termination. Additionally, entry into
Streaming Data protocol may actually decrease performance if the data
transfers cannot be sufficiently sustained.  The point at which entry
into the Streaming Data protocol yields a performance benefit depends
on the overhead, included in the slave design, to enter and to exit,
as well as the rate at which data can be expected to be supplied.
For example, if it takes four cycles to enter and two cycles to exit
Streaming Data and only two packets of data are available for
transfer, this is detrimental to performance.

      Our design also chose to include, as criteria, requi...