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Device Multiplexer With Multiple Host Capability

IP.com Disclosure Number: IPCOM000102039D
Original Publication Date: 1990-Oct-01
Included in the Prior Art Database: 2005-Mar-17
Document File: 1 page(s) / 41K

Publishing Venue

IBM

Related People

Manka, RS: AUTHOR [+3]

Abstract

An operator may wish to have a terminal device communicate with more than one host system. In the past it was necessary to provide an additional media link to the device for each host connection. Manipulation of a physical switch was required to select the desired media link or a manual disconnect-reconnect operation was performed.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 84% of the total text.

Device Multiplexer With Multiple Host Capability

       An operator may wish to have a terminal device
communicate with more than one host system.  In the past it was
necessary to provide an additional media link to the device for each
host connection.  Manipulation of a physical switch was required to
select the desired media link or a manual disconnect-reconnect
operation was performed.

      The IBM 3274 Remote Fan Out Box and Fan Out Box Wrap have been
extended to allow multiple hosts to be connected into the Fan Out
Box.  This multiple host "feed-in" allows the outboard device
operators the choice of selecting the desired host connection.
Selection is made through the normal device keyboard.

      The present invention was developed as a modification to the
IBM 3299 Fan Out Box and allows multiple input ports instead of just
one.  The switching function is accomplished as follows:

      An operator at one of the attached displays depresses a
specific key combination, for example, ALT/INSERT.  When the
logically attached control unit receives the unique scan code, it
responds with a FOB WRAP and a TERMINAL RESET command setting a
specific coax bit, e.g. coax bit 11. This causes the addressed device
to be switched into another controller.  The response to the wrap is
received as a normal poll response observing the appropriate QUE
(error, keyboard, or status) based on TD byte 1 issued with the wrap
command.  The present invention sends a clean...