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Eight-Port Multiplexer for a Twinaxial Work Station Controller

IP.com Disclosure Number: IPCOM000119233D
Original Publication Date: 1991-Jan-01
Included in the Prior Art Database: 2005-Apr-01
Document File: 4 page(s) / 119K

Publishing Venue

IBM

Related People

Comp, CM: AUTHOR [+2]

Abstract

If a customer needs to connect many Work Stations (WSs) in a different building from where the twinaxial Work Station Controller (WSC) is located, separate cables would have to be run for each port. Described is a hardware design for an eight-port multiplexer built into a WSC. This would allow the customer to run only one long twinaxial cable for the eight ports off of one WSC. An external box would also be required to demultiplex the signal back to eight ports. This will also be described.

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

Eight-Port Multiplexer for a Twinaxial Work Station Controller

      If a customer needs to connect many Work Stations (WSs)
in a different building from where the twinaxial Work Station
Controller (WSC) is located, separate cables would have to be run for
each port.  Described is a hardware design for an eight-port
multiplexer built into a WSC.  This would allow the customer to run
only one long twinaxial cable for the eight ports off of one WSC.  An
external box would also be required to demultiplex the signal back to
eight ports. This will also be described.

      A typical twinaxial Work Station Controller (WSC) would connect
through 8 ports, supporting up to seven WS per port. If a customer
needed to locate all his 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 500 feet away from the system, each port
would need to have a 5000-foot cable to reach the WS.  Fig. 1 shows
this.

      Described is an 8-port multiplexer built into the WSC logic.
For the same example as shown in Fig. 1, only a single long cable
would be required.  Fig. 2 shows this.

      An additional benefit of this design is that the WSs can now be
located farther away because the 8-port demultiplexer redrives the
signal.

      A typical workstation protocol transmission is shown in Fig. 3.
When using the 8-port multiplexed mode of operation, the signal would
be modified to include a port select address.  The transmission shown
in Fig. 4 is what the WSC would transmit to the 8-port demultiplexer.
The 8 port demultiplexer would "strip" out the port address
information, using this to select the appropriate port, and would
only send the normal WS protocol signal to the WS. The selection of
normal mode versus multiplexed mode could be automatic.  One
possibility would be to designate Port 0 of the WSC as the
multiplexed port when in multiplexed mode. The WSC Licensed Internal
Code (LIC) would issue a new Read Device ID command to address 7 (a
reserved address) on port 0.  The 8-port demultiplexer will be
designed to respond to this command, thus indicating its presence.
The WSC LIC would then set the WSC into multiplexed mode and use port
0 for all transmissions.

      The following list describes a receive operation for the 8-port
multiplexer/demultiplexer.  Refer to Fig. 5 for a block diagram of
the 8-port demultiplexer.
1.  The WSC transmits the Star...