Self-pacing serial keyboard interface for data processing system

Details Self-pacing serial keyboard interface for data processing system Self-pacing serial keyboard interface for data processing system

1981-08-12

1984-07-17

Wise, Edward J.

Boots, shoes, and leggings

364518, 364900, G06F 1502

Patent

active

044609574

ABSTRACT:
A serial keyboard interface (28) connects a self scanning programmable serialized keyboard (40) to the system bus (10) of a data processing system. A cable (42) containing only a clock wire (52) and a data wire (58) provides the connection. The keyboard transmits a 9-bit scan out code consisting of a start bit followed by eight serial data bits. The keyboard clock line (52) is connected to the clock or shift terminal of a serial-to-parallel shift register encoder (62) for shifting the data bits on data line (58) into the encoder which has eight parallel output data lines (A, B . . . G, H) connected to the system bus. When the encoder (62) contains a complete scan out frame, the start bit is in the most significant stage (h') and sets the D-type latch (68) to apply a CPU interrupt request to the system bus (10). At this time, the Q output of latch (68) pulls down the data line to ground potential, thereby disabling the data line and preventing further keyboard transmission of data. When the interrupt request is granted by the CPU, a clear signal resets latch (68) to remove ground potential from data line (58) and thereby permit further transmission of data.

REFERENCES:
patent: 3501749 (1970-03-01), Cuccio
patent: 3980994 (1976-09-01), Ying et al.
patent: 4126898 (1978-11-01), Spangler et al.
patent: 4386410 (1983-05-01), Pandya et al.
M. D. Alger et al., "Remote Keyboard Interface", Wireless World, vol. 87, No. 1545, Jun. '81, pp. 77-78.
"An 8048-Based Keyboard/Display Module", Wescon Conference Record, Sep. 1977, 27/2 pp. 1-4.
R. A. DuPont et al., "Serializer/Deserializer Apparatus", IBM Technical Disclosure Bulletin, vol. 22, No. 7, Dec. '79.
IBM Personal Computer Reference Manual, Aug. '81, pp. D-10 and D-12.

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