Interrupt control switch interface system

Details Interrupt control switch interface system Interrupt control switch interface system

1986-04-10

1988-08-02

Zache, Raulfe B.

Boots, shoes, and leggings

G06F 300

Patent

active

047617624

ABSTRACT:
Switch contacts are monitored by a computer for change of status (open or closed) without polling them. The apparatus comprises an input port module and up to eight switch reader modules, with 128 switch contacts to each. The input port module has four Z80 PIOs providing a total of eight ports for the switch reader modules, and a S-100 bus to the computer. In each switch reader module, in a RUN mode, the operation is to address the switch contacts sequentially and via a latch to load the status as data into a 128-bit shift register, and then to compare the current and previous states represented by the inputs and outputs of the shift register. If the switch contact being addressed has changed state, the comparator generates an interrupt to the processor. At the same time that an interrupt is generated, a scan inhibit command is supplied from a comparator to stop a clock. Data from an address counter and the latch are supplied via the input port module to the processor. The processor then returns a ready signal to resume the scan. There is also a LOAD mode using 512 (4.times.128) read operations to cycle the clock and load the 128 bits of the shift register.

REFERENCES:
patent: 3892915 (1975-07-01), Budworth et al.
patent: 4001785 (1977-01-01), Miyazaki et al.
patent: 4180860 (1979-12-01), Driscoll et al.
patent: 4209841 (1980-06-01), Bambara et al.
patent: 4338677 (1982-07-01), Morrill, Jr. et al.
patent: 4377853 (1983-03-01), Dockal
patent: 4443860 (1984-04-01), Vidalin

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