Control unit for input/output devices

Claim 2

In a computing system including a central processing unit, a memory shared by the I/O channels and the central processing unit, and instruction unit for providing commands to said computing system, said channels providing an interface for connecting external equipment to the computing system including peripheral devices to be used for system I/O purposes, said interface including common bus lines for transmitting commands and data to such equipment connected to said interface, the improvement which comprises a special control unit connected to said interface including: means for receiving data and command messages from said central processing unit, means for recognizing that a received message on the interface is directed to a specified peripheral device via said special control unit; means for decoding commands from said central processing unit for specified peripheral devices connected to said special control unit, means for transmitting said commands to a specified peripheral device and for setting up data paths between said peripheral device and the central processor unit; and means for signalling to the central processor that a requested task has been completed by the peripheral device.

Claim 3

A computing system including a special control unit as set forth in claim 1 wherein: commands from the central processing unit may have several command word formats; and means responsive to certain bits in the command words for changing the control function of other bits in the command word whereby an increased number of control commands may be given to the peripheral devices.

Claim 4

A computing system including a special control unit as set forth in claim 2 including common bus lines connected between said SCU and the system interface means in said special control unit for receiving both data and commands over said common bus lines and register means for recognizing and separately storing said data and commands.

Claim 5

A computing system including a special control unit as set forth in claim 3 including means for transmitting commands for execution to the intended peripheral devices.

Claim 6

A computing system including a special control unit as set forth in claim 1 including: means in the special control unit responsive to a command from the central processing unit for changing the characteristic address of a peripheral device attached to said special control unit, said means including an address holding register within said special control unit for storing an address characteristic of both the peripheral device and said control unit.

Claim 7

A computing system including a special control unit as set forth in claim 5 wherein means are included in said peripheral device cooperative with control means within said special control unit for changing the contents of said address holding register within said special control unit.

Claim 8

A computing system including a special control unit as set forth in claim 6 including control means associated with said special control unit for allowing the setting of the contents of said address storing register directly by the system operator.

Claim 9

A computing system including a special control unit as set forth in claim 5 including at least two separate transmission channel means associated with each special control unit to each of which a plurality of different peripheral devices may be attached and means for selectively addressing any of said devices attached to each transmission channel over bus lines connected between each transmission channel and its associated peripheral devices.

Claim 10

A computing system including a special control unit as set forth in claim 8 including means for making a direct connection between a device attached to one of said transmission channels and a different device attached to another transMission channel, and means for disconnecting the special control unit from the system interface while the operation requiring said direct connection is being performed.

Claim 11

A computing system including a special control unit as set forth in claim 9 wherein at least two said special control units may be attached to the system interface, each said special control unit including: means for recognizing its own specific address and for responding accordingly; and means for connecting a peripheral device connected to one said special control unit to a peripheral device connected to a different special control unit.

Claim 12

A computing system including a special control unit as set forth in claim 9 wherein each transmission channel within a special control unit normally has a fixed number of data transmission lines assigned thereto for communication with the system I/O interface, means within said special control unit for borrowing a predetermined portion of the data lines normally assigned to another transmission channel by a first transmission channel when it is desired to transmit expanded data over the system I/O interface to the central computing system.

Claim 13

In a computing system including a central processing unit, I/O channels providing an interface for connecting external equipment including peripheral devices used for performing system I/O functions to the computing system, said interface including means for transmitting commands and data to external equipment connected to said interface over common bus lines which may be shared with various external equipment units, a memory shared by the I/O channels and the central processing unit, and an instruction unit, the improvement which comprises a special control unit connected to said interface including: means including register means for receiving data and command messages from said central processing unit; means connected to said receiving means for recognizing that a received message on the interface is directed to said special control unit; means connected to said register means for decoding command words from said central processing unit for specified peripheral devices connected to said control unit; logic circuit means for changing the control function of various bits in the command word whereby an increased number of control commands may be given to the peripheral devices; means in said special control unit for receiving both data and commands over said common bus lines including means for recognizing and separately storing said data and commands; means for transmitting commands to the intended peripheral device from said storing means for execution; means for setting up data paths between a specified peripheral device and the central processing unit; and means for signalling to the central processing unit that a requested task has been completed by the peripheral device.

Claim 14

In a computing system including a central processing unit, I/O channels providing an interface for connecting external equipment including peripheral devices used for performing system I/O functions to the computing system, said interface including means for transmitting commands and data to external equipment connected to said interface over common bus lines which may be shared with various external equipment units, a memory shared by the I/O channels and the central processing unit, and an instruction unit, the improvement which comprises a special control unit connected to said interface including: means including register means for receiving data and command messages from said central processing unit; means connected to said receiving means for recognizing that a received message on the interface is directed to said special control unit; means connected to said register means for decoding command words from said central processing unit for specified peripheral devices connected to said control unit; logic circuit means for changing the control function of various bits in the command word whereby an increased number of control commands may be given to the peripheral devices; means in said special control unit for receiving both data and commands over said common bus lines including means for recognizing and separately storing said data and commands; means for transmitting commands to the intended peripheral device from said storing means for execution; means for setting up data paths between a specified peripheral device and the central processing unit; and means for signalling to the central processing unit that a requested task has been completed by the peripheral device.

Claim 15

A computing system including a special control unit as set forth in claim 12 including: at least two separate transmission channel means associated with each special control unit to each of which a plurality of different peripheral devices may be attached; means for selectively addressing any of said devices attached to such transmission channel; means for directly connecting a device attached to one of said transmission channels; to a different device attached to another transmission channel; and means for disconnection the special control unit from the system interface while the operation requiring said connection is being performed.