Leo A Sharp, 753375 NW 24Th Ter, Boca Raton, FL 33431

4514823, Apr 30, 1985

Jan 15, 1982

6/339525

Richard N. Mendelson - Boca Raton FL
Douglas M. O'Neal - Boca Raton FL
Leo A. Sharp - Boca Raton FL

International Business Machines Corporation - Armonk NY

G06F 900

364900

There is disclosed apparatus and a method for extending a parallel channel of the host processor over a serial link to a remote peripheral device. The apparatus includes a microprocessor within I/O channel extension logic which responds to either instructions or data from a host processor. The instructions are of the type commanding the I/O device to perform a specific operation and the data is provided in response to requests for data from the I/O device. The channel extension logic is coupled to the host processor's channel and thus is able to obtain data from the host storage by cycle steal techniques. Within the channel extension logic are means to serialize the information and transmit it in a serial manner over the link. The microprocessor within the channel extension logic creates a frame, including a control byte, which identifies the type of information followed by the data, which frame is then communicated over the serial link to the I/O device. The I/O device also includes a microprocessor and associated logic which responds to the frames communicated by the channel extension logic and generates a frame consisting of a control byte identifying the information type and associated data which is then communicated back over the serial link to the channel extension logic to request action by the channel extension logic or indicate completion of the operation.