USER MANUAL, MSD-4, PT# 101012
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EAST COAST DATACOM, INC.
CHAPTER 1 - INTRODUCTION
1.1
FUNCTIONAL
DESCRIPTION
The MSD-4 provides the network manager with a cost-effective means of expanding existing,
leased line polled networks without adding computer ports or communications links. With the
MSD-4, up to four terminals can share the same port and communications link using the
contention and control protocols normally resident in the host hardware and software. Once
installed, system and network efficiency are increased through higher host processor utilization
coupled with the significant decrease in idle time between host / terminal traffic sessions.
Ideal for either synchronous or asynchronous network environments, the MSD-4 is protocol
transparent at data rates up to 19.2Kbps. Data arriving at the Master Port is continually
broadcast to all Sub-channels. The user is presented with two modes of operation for terminal
access. The first mode is the attached terminal device(s) that raises the RTS control signal is
automatically given control of the MSD channel until data transmission is complete. The second
mode is the attached terminal device(s) that transition data from Mark to Hold is automatically
given control of the MSD until data transmission is complete. This is commonly called the “OR”
mode of operation. Clocking in both modes of operation is accomplished from the attached
Modem. The MSD-4 may also be used in broadcast only applications as ref. in Section 2.6.
The MSD-4 incorporate optional Anti-Streaming circuitry. If enabled, Anti-Streaming will
automatically remove a defective terminal from service if the Data / Control criteria is present
for the user predefined clock selection period.
Housed in a sturdy metal enclosure and equipped with a 110/220 VAC switch selectable linear
power supply, the MSD-4 will provide in excess of 100,000 hours of reliable service.
Figure
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TYPICAL
APPLICATION
