High performance I/O controller for transferring data between a host processor and multiple I/O units.

摘要

A first storage accessing circuitry (microprocessor (11) and chip select decoder) provides a data transfer path between the controller storage unit (22) and an I/O unit (e.g. 3). A second storage accessing circuitry (direct memory access contoller (13) and chips select decoder) supplies host processor main storage addresses to the host processor (1) and controller storage addresses to the controller storage unit (22) for enabling the transfer of data between the host processor main storage unit (7) and the controller storage unit (22) in a first data transfer mode (e.g., cycle steal mode). A third storage accessing circuitry (address decoder (23) and storage control logic) is responsive to addresses received from the host processor (1) for supplying addresses to the controller storage unit (22) for enabling the transfer of data between the host processor (1) and the controller storage unit (22) in a second data transfer mode (e.g., direct program control mode). This second mode data transfers are interleaved with the first mode data transfers. Direct program control data transfers can be performed at the same time the I/O controller is busy doing cycle steal data transfers.