Programmable unit for controlling and interfacing of I/O busses of dissimilar data processing systems

• US 5,581,741 A
• Filed: 11/16/1994
• Issued: 12/03/1996
• Est. Priority Date: 11/12/1992
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Kodukula, Sivarama K., Clark, Alan R.
• Primary Examiner(s): Ellis, Richard L.
• Application Number:
  US08/341,848
• Time in Patent Office: 748 Days
• Field of Search: 395/500, 395/200, 395/275, 395/306, 395/307, 395/308, 395/309, 395/310
• US Class Current: 703/25
• CPC Class Codes: G06F 13/4027 using bus bridges G06F13/4022 takes precedence

Abstract

A programmable I/O bus adapter for interfacing and controlling two data processing systems having dissimilar and incompatible architectures. The programmable I/O bus adapter is capable of controlling the I/O bus and adapters of each of the two data processing systems. Simultaneously, the I/O bus adapter provides for interfacing and communication between the two dissimilar data processing systems. Interfacing from the bus adapter to each data processing system is provided by circuitry provided on integrated circuit chip sets specifically designed to interface with each system. The interfacing circuitry is enabled to convert signals between each system to allow for communication. Communication paths couple the adapter to the I/O bus of each system. The ability to access and control an I/O bus and adapter of each system is provided by a microprocessor having microcode instructions stored in programmable memory. The microcode provides for self-contained operation of the I/O bus adapter by enabling it to independently perform I/O control functions of the coupled systems. The microprocessor may be implemented by using a RISC architecture microprocessor device.

Claims

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.

2. The smart bus control unit of claim 1, wherein the first bus interface selectively provides data streaming between the local bus and the first I/O bus.

3. The smart bus control unit of claim 1, wherein the first bus interface operates simultaneously with respect to the second bus interface.

4. The smart bus control unit of claim 1, wherein the DMA register comprises multiple control registers.

5. The smart bus control unit of claim 1, wherein the memory includes RAM.

6. The smart bus control unit of claim 1, wherein the local bus further includes a bypass bus interconnecting the first and second bus interfaces.

7. The smart bus control unit of claim 6, wherein the first bus interface is further programmed to exchange signals, in accordance with commands stored in the DMA register, between the second bus interface and an I/O device included in the first I/O channel such that the signals pass through the bypass bus and the first bus interface bypassing the memory.