Product information:

The Modem Sharing (MODSHR) products consist of 4 and 8 port units.
The units provide the network manager with a cost effective means of expanding existing, leased line polled networks without adding computer ports or communications links.
Up to eight 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 units are protocol transparent at data rates up to 128Kbps.
Data arriving at the Master Port is continually broadcast to all Subchannels. The attached terminal device that raises the RTS control signal is automatically given control of the unit until data transmission is complete.
Clocking is accomplished from the attached Modem.
The sharers 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 selection period.
Housed in a sturdy metal enclosure and equipped with an internal 110/220VAC switch selectable linear power supply.
Application Multiple Sync/Async terminal or DTE devices operating in a polled environment, to share one Modem
Capacity One to eight RS-232 Sync/Async devices
Interface EIA RS-232, CCITT V.24 using DB-25 female connectors, +/- 15KV ESD Protection
Data Rates Up to 128Kbps
Data Format Data transparent at all data rates
Timing External; from attached Modem
Anti-Streaming Automatic . . .Selectable time out intervals, Disable . . . . .Selectable via dip switch
Terminal Service Modes Scanning or Priority
Front Panel Indicators . . . Power, Transmit Data, Receive Data, Channel Active, Channel Stream Switches . . . . Enable/Disable of each Subchannel
Environmental Operating Temperature . .32º to 122º F (0º to 50º C)
Relative Humidity.. . . . . . .5 to 95% Non-Condensing
Altitude. . . . . . . . . . . . . ... .0 to 10,000 feet

Dimensions
Height . . . . . . . . . . . . . . .1.75 inches (4.44cm)
Width . . . . . . . . . . . . . . . 13.35 inches (33.09 cm)
Length . . . . . . . . . . . . . . 9.00 inches (22.86 cm)