Data telecommunications system and method utilizing a multi-mode modem

A method of initiating data telecommunications between two units of data terminal equipment over communication lines, each unit of said data terminal equipment having a modem connected between said unit and the communication lines, at least one of said modems being capable of operating under a special mode and under a normal mode, said special mode providing optimized data transmission that paces the flow of data between said modems and provides error detection in a transmitted data stream and automatic retransmission of said data stream by an initiating modem when an error occurs and said normal mode providing direct, nonoptimized data transmission that provides transmission of the data stream without any analysis of the data stream, said method comprising the steps of:

• (a) transmitting a stream of data characters from an initiating modem to a receiving modem over communication lines;
• (b) examining a next character in said data stream transmitted to said receiving modem;
• (c) attempting to establish a special mode link between said initiating and receiving modem if said next character is a special mode indicating character;
• (d) storing said next character in a character buffer if said special mode indicating character is not detected;
• (e) repeating steps (b) through (d) until a special mode indicating character is detected or until said character buffer fills up;
• (f) if said character buffer fills up, establishing a normal mode link with the characters in the buffer being sent to said unit of data terminal equipment upon the establishing of a normal mode link;
• (g) continuing the transmission of said data stream after said special mode or said normal mode link is established until said stream is fully transmitted.

A data telecommunications system for providing data communications between two units of data terminal equipment over communication lines comprising:

• a modem connected between each unit of data terminal equipment and the communication lines, at least one of said modems being a receiving modem capable of operating in a special mode and a normal mode, said special mode provoding optimized data transmission that paces the flow of data between two modems and provides error detection in a transmitted data stream by a receiving modem and automatic retransmission of said data stream by an initiating modem when an error occurs and said normal mode providing direct, non-optimized data transmission that provides simple transmission of the data stream without any analysis of the data stream, said modem capable of operating in said special and normal modes including:
• means for transmitting a stream of data characters from an initiating modem to a receiving modem;
• means associated with said receiving modem for detecting a special mode indicating character and for detecting a normal mode indicating character in said received stream of data characters;
• means for causing receiving modem to operate in said special mode upon the detecting of said special mode indicating character;
• means for causing receiving modem to operate in said normal mode upon the detecting of said normal mode indicating character.

A data telecommunications system for providing data communications between two units of data terminal equipment over communication lines comprising:

• a modem connected between each unit of data terminal equipment and the communication lines, at least one of said modems being capable of operating in a special mode and in a normal mode, said special mode providing optimized data transmission that paces the flow of data between said two modems and provides error detection in a transmitted data stream by a receiving modem and automatic retransmission of said data stream by an initiating modem when an error occurs and said normal mode providing direct, non-optimized data transmission that provides transmission of the data stream without any analysis of the data stream, said modem capable of operating in said special and normal modes including
• means for receiving a transmitted stream of data characters from an initiating modem;
• means for detecting a special mode indicating character in said received stream of data characters;
• buffer memory means for storing non-special mode indicating characters in said received stream of data characters;
• counter means for counting the number of characters in said buffer memory means in order to determine when said buffer memory means has been filled;
• means responsive to said detecting means for causing said modem to operate in said special mode upon detecting of said special mode indicating character;
• means responsive to said counter means for causing said modem to operate in said normal mode when said buffer memory means has filled, said means for causing said modem to operate in said normal mode also including means for transmitting characters stored in said buffer memory means to said unit of data terminal equipment to which said modem is connected prior to the transmission of the remainder of said data stream.

A modem for connecting between a unit of data terminal equipment and communication lines to facilitate data telecommunications, said modem being capable of operating in a special mode and a normal mode, said special mode providing optimized data transmission that paces the flow of data between said two modems and provides error detection in a transmitted data stream by a receiving modem and automatic retransmission of said data stream by an initiating modem when an error occurs and said normal mode providing direct, non-optimized data transmission that provides simple transmission of the data stream without any analysis of the data stream, said modem comprising:

• means for receiving a transmitted stream of data characters from an initiating modem;
• means for detecting a special mode indicating character and for detecing a normal mode indicating character in said received stream of data characters;
• means for causing said modem to operate in said special mode upon the detecing of said special mode indicating character;
• means for causing said modem to operate in said normal mode upon the detecting of said normal mode indicating character.

A modem for connecting between a unit of data terminal equipment and communication lines to facilitate data telecommunications, said modem being capable of operating in a special mode and in a normal mode, said special mode providing optimized data transmission that paces the flow of data between said two modems and provides error detection in a transmitted data stream by a receiving modem and automatic retransmission of said data stream by an initiating modem when an error occurs and said normal mode providing direct, non-optimized data transmission that provides transmission of the data stream without any analysis of the data stream, said modem comprising:

• means for receiving a transmitted stream of data characters from an initiating modem;
• means for detecting a special mode indicating character in said received stream of data characters;
• buffer memory means for storing non-special mode indicating characters in said received stream of data characters;
• counter means for counting the number of characters in said buffer memory means in order to determine when said buffer memory means had been filled;
• means responsive to said detecting means for causing said modem to operate in said special mode upon the detecting of said special mode indicating character;
• means responsive to counter means for causing said modem to operate in said normal mode when said buffer memory means has filled, said means for causing said modem to operate in said normal mode also including means for transmitting characters stored in said buffer memory means to said unit of data termianl equipment to which said modem is connected prior to the transmission of the remainder of said data stream.