Abstract: This I/O interface permits attachment of a data processing system to devices having different "handshaking" protocols and bit-parallel data exchange capacities. Handshaking control circuits permit the system to communicate with devices variously in pulsed and interlocked modes. Timer circuits provide a variety of different time reference signals for transfer to devices. Switching options associated with the timer permit selective use of timer outputs as pulsed mode handshaking functions. A counter circuit and associated interface port permit the system to count events associated with device-originated pulses. A switching option permits the counter incrementing operations to be governed by timer outputs. The interface also contains path selection lines. In one mode these lines define high speed exchange of data between a primary system processor and devices in various bit-parallel formats and over various buses designatable by a systems processor.

Abstract: A dual mode microprocessor acts either as a front-end IO controller processor relative to a primary host processor and device or as a secondary data processor having independent storage, processing and IO capabilities. Host software prepares a list of device control block (DCB) arrays, which contain primary commands interpretable by the microprocessor so as to evoke these modes. Each DCB contains a chaining bit permitting its interpretation sequence to be chained (or not chained) to another DCB sequence, and a mode bit defining either a high speed DI/DO (HS) mode of operation or a programmable offline (PO) mode. In HS mode the microprocessor conditions associated adapters to transfer a specified amount of data between the host memory and device, performing this transfer in an autonomous manner, i.e., without assistance from either processor.