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A Method to Detect the Extended Mode of Parallel Port Hardware

IP.com Disclosure Number: IPCOM000123098D
Original Publication Date: 1998-May-01
Included in the Prior Art Database: 2005-Apr-04
Document File: 2 page(s) / 49K

Publishing Venue

IBM

Related People

Schroeder, FJ: AUTHOR

Abstract

This invention defines a chip set independent method that can be used to detect when a parallel port is configured to extended mode. Performance and throughput benefits can be realized in extended mode over compatible mode when performing peripheral to host data transfers using the IEEE-1284 Standard Signaling Method for a Bi-directional Parallel Peripheral Interface for Personal Computers.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 72% of the total text.

A Method to Detect the Extended Mode of Parallel Port Hardware

   This invention defines a chip set independent method that
can be used to detect when a parallel port is configured to extended
mode.  Performance and throughput benefits can be realized in
extended mode over compatible mode when performing peripheral to host
data transfers using the IEEE-1284 Standard Signaling Method for a
Bi-directional Parallel Peripheral Interface for Personal Computers.

   Given that the nibble mode signaling protocol is supported
on all parallel port modes of operation, given an IEEE-1284
compliant device must support nibble mode data transfers, given that
an IEEE-1284 compliant device must support returning its device id
string in nibble mode, and given that the byte mode signaling
protocol is only supported on the extended parallel port mode of
operation, by receiving an equal comparison when comparing the
results of querying the device id using the nibble mode signaling
protocol to the results using the byte mode signaling protocol, it
can be deduced that the parallel port mode of operation must be
extended mode.  Future transfers should then used the byte mode
signaling protocol and achieve improved performance and throughput
since the nibble mode sends half as much data per time period as byte
mode.

      The following steps comprise the invention.
  1.  Set the communication mode with the device to nibble mode.
  2.  Query the device id string from the device using n...