Variable speed line adapter

Claim 2

In a line adapter for communication systems of the start-stop type wherein a character is represented by a signal having a plurality of selectively coded bits preceded by a start bit and followed by a stop bit and wherein terminals transmitting character signals at different speeds may be selectively connected to a line adapter, the combination of: a plurality of oscillators, one for each of said different speeds; gating means to pass the output of each of said oscillators to a common line adapter control lead; signal decoding means initiated by reception of said start bit and controlled by the oscillator signals on said control lead; initializing means to set said gating means to pass a predetermined one of said oscillator outputs to said control lead; character control devices to indicate when a stop bit should be present in a received character transmitted at the transmission rate of said predetermined oscillator output; and a gating means control circuit activated by said character control devices to prevent alteration of said gating means if said received character signal is at a stop bit level or to alter said gating means to pass the output of a different oscillator to said control lead if said character signal is not at a stop bit level.

Claim 3

A line adapter as recited in claim 1 wherein: said gating means comprises a plural state circuit; said gating means control circuit comprises a bistable device initially set to one stable state; a circuit gated by said bistable device when in said one state to change the state of said plural state circuit if the received character signal does not have a stop bit when sampled by said character control devices; and another circuit to set said bistable device to its other state if the sampled character signal does have a stop bit.

Claim 4

In a line adapter for communications of the start-stop type in which a character is represented as a predetermined number of selectively variable bits preceded by a start bit and followed by a stop bit and wherein any one of a plurality of terminals transmitting at different rates may be connected to a line adapter, the combination of: a plurality of adapter timing circuits, one for each of said different rates; gating means to pass the timing signals on one of said timing circuits to a common timing lead; an adapter initiating means to set said gating means to pass a predetermined one of said timing signals to said timing lead; a transmission rate detecting device set by said initiating means and activated by reception of a start bit of a character to enable selection of one of said timing signals for control of said line adapter by indicating the time for reception of the stop bit of a character transmitted at the rate corresponding to said predetermined one of said timing signals; means under control of said initiating means and said rate detecting device to test for the occurrence of a stop bit; and gating control means activated when said controlled means does not detect a stop bit to set said gating means to pass the timing signals corresponding to the transmission rate of the character representations being received.

Claim 5

In a line adapter for communications of the start-stop type in which a character is represented as a predetermined number of selectively variable bits preceded by a start bit and followed by a stop bit and wherein any one of a plurality of terminals transmitting at different rates may be connected to a line adapter, the combination of: a plurality of adapter timing circuits, one for each of said different rates; gating means to pass the timing signals on one of said timing circuits to a common timing lead; an adapter initiating means to set said gating means to pass a predetermined one of said timing signals to said timing lead; a transmission rate detecting device set by said initiating means and activated by reception of a start bit of a character to enable selection of one of said timing signals for control of said line adapter by indicating the time for reception of the stop bit of a character transmitted at the rate corresponding to said predetermined one of said timing signals; means under control of said initiating means and said rate detecting device to test for the occurrence of a stop bit; and gating control means activated when said controlled means does not detect a stop bit to set said gating means to pass the timing signals corresponding to the transmission rate of the character representations being received.