1. A smart bus control unit for coupling a mainframe computer to a personal computer, wherein the personal computer includes an I/O channel providing a communications path for at least one of data, control information, and address information and including a first I/O bus, at least one PC processor, and at least one I/O adapter, and wherein said mainframe computer includes a central processing unit coupled to a second I/O bus and a memory unit, said smart bus control unit comprising: a local bus; a memory electrically coupled to the local bus; a first bus interface electrically coupled to the local bus and the first I/O bus, comprising: a local register to exchange signals between the first I/O bus and a second bus interface via the local bus; a DMA register operable in a direct program control mode to receive and store parameters for signal transfer operations from the PC processor, and also operable in linked-list mode to obtain parameters for signal transfer operations from the memory and store the parameters; said first bus interface being selectively operable as a master or a slave in relation to the first I/O bus; said first bus interface being operable to exchange signals, in accordance with the parameters stored in the DMA register, between the second bus interface and one of the following via the local bus: (1) the first I/O bus; (2) a planar processor included in the first I/O channel; (3) an I/O adapter included in the first I/O channel; (4) a channel memory included in the first I/O channel; and (5) an I/O device included in the first I/O channel; a second bus interface electrically coupled to the local bus and the second I/O bus, comprising: at least two ping-pong buffers to alternately exchange successive signals between the second I/O bus and the local register via the local bus; and a high priority memory to interrupt exchanging of signals by the ping-pong buffer by exchanging signals between the second I/O bus and the local register via the local bus; and a local processor means electrically coupled to the local bus and programmed for initiating exchanging of signals by the first bus interlace and second bus interface in accordance with the parameters stored in the DMA register.