Browse Prior Art Database

Programmable Eight Port Multiplexer/ Demultiplexer for a Twinaxial Work Station Controller

IP.com Disclosure Number: IPCOM000107189D
Original Publication Date: 1992-Jan-01
Included in the Prior Art Database: 2005-Mar-21
Document File: 8 page(s) / 259K

Publishing Venue

IBM

Related People

Dancker, GA: AUTHOR

Abstract

If a customer needs to connect Work Stations (WSs) in a different building from where the twinaxial (5250 protocol) Work Station Controller (WSC) is located, separate cables would have to be run from each port. In some cases, all ports off a WSC would be connected to a different building; in other cases, some of the ports would be connected to WSs in a different building, some would be connected to the WSs in the same building as the WSC. This article describes a programmable two- to eight-port multiplexer built into a twinaxial WSC and an external demultiplexer box. This allows connecting a single twinaxial cable or a pair of fiber-optic cables between buildings, which carries the signal for multiple ports.

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Programmable Eight Port Multiplexer/ Demultiplexer for a Twinaxial Work Station Controller

       If a customer needs to connect Work Stations (WSs) in a
different building from where the twinaxial (5250 protocol) Work
Station Controller (WSC) is located, separate cables would have to be
run from each port.  In some cases, all ports off a WSC would be
connected to a different building; in other cases, some of the ports
would be connected to WSs in a different building, some would be
connected to the WSs in the same building as the WSC.  This article
describes a programmable two- to eight-port multiplexer built into a
twinaxial WSC and an external demultiplexer box.  This allows
connecting a single twinaxial cable or a pair of fiber-optic cables
between buildings, which carries the signal for multiple ports.

      A typical twinaxial Work Station Controller (WSC) would connect
through 8 ports, supporting up to seven Work Stations (WSs) per port.
If a customer needed to locate some or all their WSs in an area a
long distance from the system, a separate cable for each port would
have to be run. For example, if the WSs were 5000 feet away from the
system, each port would need to have a 5000-foot cable to reach the
WS.  Fig. 1 shows this.

      This article describes a 2 to 8 port, programmable multiplexer
built into the WSC logic and the external demultiplexer box.  For the
same example as shown in Fig. 1, only a single long cable would be
required to attach multiple ports at a long distance from the WSC, as
shown in Fig. 2.  Figs. 3 and 4 show some other possible connection
options.

      The following two registers are used to control the 8-port
multiplexer that is built into the WSC.  Any 2 to 8 ports can be
multiplexed over a single port.  One restriction is that if, for
example, ports 1, 2, 3, and 4 are selected for multiplexing, then
port 1, 2, 3, or 4 must be selected as the multiplexed port;
otherwise, an error will be posted.
     1.  Ports to Multiplex Register:  This 8-bit register is used to
select which ports are to be multiplexed.  Any combination of ports
can be chosen to multiplex (see Fig. 5).
     2.  Multiplex Port Register:  This 4-bit register is used to
select which port to use for multiplexing.  This is the port that the
external demultiplexer would be attached to.  This register is also
used to select the optical interface on the WSC (see Fig. 6).
     Bits 2 to 0 at "000" select port 0 for the multiplex port.
     Bits 2 to 0 at "001" select port 1 for the multiplex port.
     Bits 2 to 0 at "010" select port 2 for the multiplex port.
     Bits 2 to 0 at "011" select port 3 for the multiplex port.
     Bits 2 to 0 at "100" select port 4 for the multiplex port.
     Bits 2 to 0 at "101" select port 5 for the multiplex port.
     Bits 2 to 0 at "110" select port 6 for the multiplex port.
     Bits 2 to 0 at "111" select port 7 for the multiplex port...