Browse Prior Art Database

Dynamic Datapath Selection for Unpredictable Transger Starts

IP.com Disclosure Number: IPCOM000111239D
Original Publication Date: 1994-Feb-01
Included in the Prior Art Database: 2005-Mar-26
Document File: 4 page(s) / 94K

Publishing Venue

IBM

Related People

Blackmon, HL: AUTHOR [+4]

Abstract

A method of improving the performance when using a Memory Card Data Fastpath scheme is disclosed. The invention can be used for cases when the start of the return data transfer is variable during a DRAM Read operation.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

Dynamic Datapath Selection for Unpredictable Transger Starts

      A method of improving the performance when using a Memory Card
Data Fastpath scheme is disclosed.  The invention can be used for
cases when the start of the return data transfer is variable during a
DRAM Read operation.

This invention improves performance when using a Memory Card Data
Fastpath scheme.

      To briefly summarize the referenced scheme: To improve
performance on a memory card DRAM access, the option of selecting one
of two paths in the Data Flow logic chip is provided.  The 'Fast'
path causes the data to bypass the ECC correction and a data buffer.
The 'Slow' path causes the data to go through the ECC correction and
to be written into a data buffer.  Selecting the 'Fast' path allows
the data to be returned to a processor quicker which improves
performance.  The selection of the path is relatively static and is
controlled by an architected latch which can be loaded by software.
A block diagram of this can be seen in Fig. 1.

      The memory card interface back to the processor is such that
other activity in the system may prevent the data from being returned
at the optimum cycle for the 'Fast' path.  If the start of the data
transfer back to the processor is delayed at all, then the entire
transfer gets out of alignment and must be marked invalid as it is
returned to the processor.  When this occurs, the original command
must be retried and the performance is decreased.  This invention
improves the performance of a memory card that uses the 'Fastpath'
scheme, when the start of the return data transfer is variable.

      The general idea of this invention is to create another data
path option and make the 'Fastpath' scheme more dynamic when
selecting which path to use.  The object is to be able to react and
handle the variable start of the return data transfer quickly.  The
idea is to design the dataflow logic so that it automatically
provides the 'best' data regardless of when the return transfer
starts.  A block and timing diagram of this can be seen in Fig. 2.

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