Microcomputer system with input/output unit connected to the remainder of the system by a single multibit bus and several sequential data lines
First Claim
1. A simplified computer system having a computer unit of the so-called microcomputer type and an input-output unit, connected to said computer unit over a data bus, for transferring externally determined values to said computer unit, said input-output unit having a register-and-counter portion comprising a plurality of registers and a plurality of counters, said system further comprising the improvement which consists in that, in order to avoid the use of a separate multiple-connection address bus between said computer unit and said input-output unit:
- only a single multibit bus serving as said data bus, and not substantially more than four one-way signal connections, of which two are respectively for chip-select (CS) and data strobe (DS) functions, are provided to interconnect said computer unit and said input-output unit, and for contribution to the addressing of said register-and-counter portion of said input-output unit, the latter unit has a control circuit (13) connected to a port of said data bus and also connected to said computer unit by said not more than four signal connections;
said control circuit (13) includes a decoder (40) having an input connected to said data bus port, for providing a variety of control commands and directing said commands from said data bus respectively to various registers and counters of said register-and-counter -portion by way of different outputs (41-46) of said decoder which are connected to said register-and-counter portion (76) of said input-output unit.
1 Assignment
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Accused Products
Abstract
The destination of commands provided by a microcomputer to an input-output unit over a data bus is provided without an address bus, while a control circuit in the input-output unit is connected with the microcomputer by connections for only three binary signals in one direction, "clear", chip-select and data strobe and one in the other, namely interrupt. The control circuit has a decoder connected to the data bus that sorts out the commands, feeding the outputs through a gate array that are enabled by the chip-select and data strobe signals for timing. Commands for switching, such as beginning and ending counts, and so on are one-byte commands directly transmitted to the appropriate circuits of the input-output. Read and write commands are two-byte commands sequenced by a sequencing and lockout circuit, the circuit selected in first byte being activated to read or write to or from the data bus in the second byte while the decoder is blocked. The direction of transmission of the data bus is controlled over a single connection from the control circuit in accordance with whether a write command is or is not present.
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Citations
11 Claims
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1. A simplified computer system having a computer unit of the so-called microcomputer type and an input-output unit, connected to said computer unit over a data bus, for transferring externally determined values to said computer unit, said input-output unit having a register-and-counter portion comprising a plurality of registers and a plurality of counters, said system further comprising the improvement which consists in that, in order to avoid the use of a separate multiple-connection address bus between said computer unit and said input-output unit:
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only a single multibit bus serving as said data bus, and not substantially more than four one-way signal connections, of which two are respectively for chip-select (CS) and data strobe (DS) functions, are provided to interconnect said computer unit and said input-output unit, and for contribution to the addressing of said register-and-counter portion of said input-output unit, the latter unit has a control circuit (13) connected to a port of said data bus and also connected to said computer unit by said not more than four signal connections; said control circuit (13) includes a decoder (40) having an input connected to said data bus port, for providing a variety of control commands and directing said commands from said data bus respectively to various registers and counters of said register-and-counter -portion by way of different outputs (41-46) of said decoder which are connected to said register-and-counter portion (76) of said input-output unit. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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Specification