Communication adapter circuit

Claim 1

A multi-protocol communication adapter circuit for interfacing a processor with a modem for providing communication between the processor and a remote terminal, comprising: a data transfer bus connected to said processor; a plurality of control lines connected to said processor; an asynchronous and bisynchronous control circuit connected to said data transfer bus and to said modem for controlling data transfer between said processor and said remote terminal under asynchronous and bisynchronous protocols, respectively, said asynchronous and bisynchronous control circuit connected to at least one of said control lines for receiving command signals from said processor; an SDLC (Synchronous Data Line Control) control circuit connected to said data transfer bus and to said modem for controlling data transfer between said processor and said remote terminal under SDLC protocol, said SDLC control circuit connected to at least one of said control lines for receiving command signals from said processor, and having a clock recovery mechanism for generating a data clock signal; means responsive to command signals from said processor for generating a clock select command signal representing the rate of data transfer between said processor and said remote terminal; and a clock selection circuit connected to said SDLC control circuit to receive said data clock signal, and to said means for generating to receive a clock select command signal, said clock selection circuit also connected to said asynchronous and bisynchronous control circuit for providing said data clock signal thereto during operation under said bisynchronous protocol, and for providing said data clock signal to said SDLC control circuit during operation under SDLC protocol.

Claim 7

A method for providing communication between a processor and a remote terminal through modems by use of one of a plurality of communication protocols, comprising the steps of: transmitting command signals through control lines from said processor to an asynchronous and bisynchronous control circuit for initialization thereof for operation in either an asynchronous or bisynchronous communication protocol; transmitting command signals through control lines from said processor to an SDLC (Synchronous Data Line Control) control circuit for initialization thereof for operation in an SDLC communication protocol, said SDLC control circuit having a clock recovery mechanism for generating a data clock signal; transmitting command signals through control lines from said processor to a clock selection circuit for setting a rate for data transfer through said asynchronous and bisynchronous control circuit or said SDLC control circuit; applying said data clock signal from said SDLC control circuit to said clock selection circuit; applying said data clock signal from said clock selection circuit to said asynchronous and bisynchronous control circuit during operation thereof under said bisynchronous protocol; and transferring data between said processor and said remote terminal through said modems and said asynchronous and bisynchronous control circuit at the data transfer rate selected by said processor.

Claim 8

A method for providing communication between a processor and a remote terminal through modems by use of one of a plurality of communication protocols, comprising the steps of: transmitting command signals through control lines from said processor to an asynchronous and bisynchronous control circuit for initialization thereof for operation in either an asynchronous or bisynchronous communication protocol; transmitting command signals through control lines from said processor to an SDLC (Synchronous Data Line Control) control circuit for initialization thereof for operation in an SDLC communication protocol, said SDLC control circuit having a clock recovery mechanism for generating a data clock signal; transmitting command signals through control lines from said processor to a clock selection circuit for setting a rate for data transfer through said asynchronous and bisynchronous control circuit or said SDLC control circuit; applying said data clock signal from said SDLC control circuit to said clock selection circuit; applying said data clock signal from said clock selection circuit to said asynchronous and bisynchronous control circuit during operation thereof under said bisynchronous protocol; and transferring data between said processor and said remote terminal through said modems and said asynchronous and bisynchronous control circuit at the data transfer rate selected by said processor.