Browse Prior Art Database

Adaptive Line Turnaround Time for Port and Different Port Operations

IP.com Disclosure Number: IPCOM000122525D
Original Publication Date: 1991-Dec-01
Included in the Prior Art Database: 2005-Apr-04
Document File: 3 page(s) / 131K

Publishing Venue

IBM

Related People

Comp, CM: AUTHOR [+3]

Abstract

A Work Station Controller (WSC) provides attachment of multiple work stations to a computer system via some type of communication protocol. Transmission errors may be caused by WSC hardware rapidly turning around a communication line. Described is how the number of certain type transmission errors can be used to adjust WSC communication line turnaround times.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 51% of the total text.

Adaptive Line Turnaround Time for Port and Different Port Operations

      A Work Station Controller (WSC) provides attachment of
multiple work stations to a computer system via some type of
communication protocol.  Transmission errors may be caused by WSC
hardware rapidly turning around a communication line. Described is
how the number of certain type transmission errors can be used to
adjust WSC communication line turnaround times.

      Work stations can include dependent displays, programmable work
stations, printers, or other devices.  In some protocols, work
stations are allowed to cable-through, where multiple work stations
can attach to the same communication line.  A typical local WSC with
attached work stations is shown in the figure.  This disclosure also
applies to remote WSCs which attach to the host processor via a
communication line instead of a system bus.

      The minimum turnaround time for transmission on the same line
is typically documented (for example, 32 usec).  A poor quality line
(for example, substandard cable) could cause transmission errors
because work stations miss commands or polls.  For a poor quality
line, quicker turnaround times will typically cause more transmission
errors than slower turnaround times.

      The WSC shown in the figure may have a single set of hardware
driver/receiver adaptor logic to communicate with all work stations.
Then, the WSC can communicate with only one work station at a time
even though there are multiple lines.  The minimum turnaround time
for transmission between different lines is probably not documented
because each work station attaches to a single line.  The above WSC
may then turnaround communication between different lines as fast as
possible (for example, less than 1 usec).  However, this can cause
transmission errors when devices such as multiplexer/demultiplexer
media converters are used (for example, multiplexing multiple lines
across one fiber-optic cable and demultiplexing back to the multiple
lines before work station attachment).

      WSCs typically retry transmission errors some number of times
before the error is considered permanent and the work stations taken
off-line.

      This disclosure involves the WSC hardware allowing the WSC
Licensed Internal Code (LIC) to adjust same line and different line
turnaround times independently as the rate of certain types of
temporary transmission errors change.  With minimal temporary errors,
same line turnaround time will be right at minimum documented values
and different line turnaround times will be as fast as possible,
resulting in optimal performance.  Otherwise, if certain temporary
errors occur between same line operations, same line turnaround times
are increased.  Similarly, if certain temporary errors occur between
different line operations, different line turnaround times are
increased.

      Specifically, the WSC hardware registers allow the WSC LIC to
set same...