I/O control system using buffer full/empty and zero words signals to control DMA read/write commands
First Claim
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1. An input/output control system connected, via a common bus to a central control unit and, via an external bus to an input/output unit, for controlling transfer of data between the central control unit and the input/output unit, said input/output control system comprising:
- a buffer memory, connected to the common bus, for momentarily storing transfer data and for outputting full and empty signals indicating full and empty states thereof;
a control register, connected to the common bus, for storing sets of data transfer control information from the central control unit, the data transfer control information including a number of words to be transferred, and for outputting a zero words signal when the number of words to be transferred is zero;
a microprocessor, connected to the common bus via said control register, for generating commands for initiating and completing data transfer under control of a microprogram;
an input/output unit control circuit, connected to the common and external buses, said buffer memory and said microprocessor, for controlling the input/output unit, only starting and finishing operations of said input/output unit control circuit being controlled by execution of the microprogram in said microprocessor;
direct memory access control means for controlling data transfer using said buffer memory in dependence upon the data transfer control information written in said control register, said direct memory access control means comprising;
an input/output unit direct memory access control circuit connected to said input/output unit control circuit and said buffer memory, for controlling data transfer between said buffer memory and said input/output unit control circuit, using the read and write commands from said microprocessor only for controlling initiation and completion of data transfer; and
a direct memory access control circuit connected to the common bus and said buffer memory, for controlling data transfer between said buffer memory and the common bus using the read and write commands only for controlling initiation and completion of data transfer; and
logic means for generating a first control signal, in dependence upon the full and empty signals, to control generation of the read and write commands by said input/output unit direct memory access control circuit and for generating a second control signal, in dependence upon the full and empty signals and the zero words signal, to control generation of the read and write commands by said direct memory access control circuit, the read and write commands controlling operation of the buffer memory.
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Abstract
In an input/output control system: a read/write operation for a control register (REG) under a program mode is achieved by hardware; the system is started or stopped under the control of firmware, and a data transfer in the system is achieved under the control of hardware. Therefore, a high speed data communication is realized, via the system, between a central control unit (CC) and an input/output unit (IO).
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Citations
23 Claims
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1. An input/output control system connected, via a common bus to a central control unit and, via an external bus to an input/output unit, for controlling transfer of data between the central control unit and the input/output unit, said input/output control system comprising:
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a buffer memory, connected to the common bus, for momentarily storing transfer data and for outputting full and empty signals indicating full and empty states thereof; a control register, connected to the common bus, for storing sets of data transfer control information from the central control unit, the data transfer control information including a number of words to be transferred, and for outputting a zero words signal when the number of words to be transferred is zero; a microprocessor, connected to the common bus via said control register, for generating commands for initiating and completing data transfer under control of a microprogram; an input/output unit control circuit, connected to the common and external buses, said buffer memory and said microprocessor, for controlling the input/output unit, only starting and finishing operations of said input/output unit control circuit being controlled by execution of the microprogram in said microprocessor; direct memory access control means for controlling data transfer using said buffer memory in dependence upon the data transfer control information written in said control register, said direct memory access control means comprising; an input/output unit direct memory access control circuit connected to said input/output unit control circuit and said buffer memory, for controlling data transfer between said buffer memory and said input/output unit control circuit, using the read and write commands from said microprocessor only for controlling initiation and completion of data transfer; and a direct memory access control circuit connected to the common bus and said buffer memory, for controlling data transfer between said buffer memory and the common bus using the read and write commands only for controlling initiation and completion of data transfer; and logic means for generating a first control signal, in dependence upon the full and empty signals, to control generation of the read and write commands by said input/output unit direct memory access control circuit and for generating a second control signal, in dependence upon the full and empty signals and the zero words signal, to control generation of the read and write commands by said direct memory access control circuit, the read and write commands controlling operation of the buffer memory.
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2. An input/output control system connected, via a common bus to a central control unit and, via an external bus to an input/output unit, for controlling transfer of data between the central control unit and the input/output unit, said input/output control system comprising:
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a buffer memory, connected to the common bus, for momentarily storing transfer data; a control register, connected to the common bus, for storing sets of data transfer control information from the central control unit; a microprocessor, connected to the common bus via said control register, for generating commands for initiating and completing data transfer under control of a microprogram; an input/output unit control circuit, connected to the common and external buses, said buffer memory and said microprocessor, for controlling the input/output unit, only starting and finishing operations of said input/output unit control circuit being controlled by execution of the microprogram in said microprocessor, said input/output unit control circuit issuing an interruption for finish signal to deactivate said microprocessor in response to the data transfer coming to an end direct memory access control means, connected to the common bus, for controlling data transfer using said buffer memory in dependence upon the data transfer control information written in said control register and, for initiation and completion of data transfer only, the commands from said microprocessor, said direct memory access control means comprising; an input/output unit direct memory access control circuit connected to said input/output unit control circuit and said buffer memory, for controlling data transfer between said buffer memory and said input/output unit control circuit; and a direct memory access control circuit connected to the common bus and said buffer memory, for controlling data transfer between said buffer memory and the common bus; and a program mode control circuit connected between the common bus and said microprocessor, for controlling data transfer under a program mode, said program mode control circuit issuing an interruption for activation signal to activate said microprocessor in response to a data transfer request from the central control circuit. - View Dependent Claims (3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23)
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Specification