Accession Number : ADD014078

Title :   Interrupt Control Switch Interface System.

Descriptive Note : Patent, filed 10 Apr 86, patented 2 Aug 88,

Corporate Author : DEPARTMENT OF THE AIR FORCE WASHINGTON DC

Personal Author(s) : Holmes, Buddy L

Report Date : 02 Aug 1988

Pagination or Media Count : 25

Abstract : This invention relates to an interrupt control switch interface system for use with a computer; and more particularly to a system for scanning a plurality of switch contacts to detect a change of status (open or closed) and generate an interrupt to a microcomputer, and then determine and transmit the address of the switch. 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 readers 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 (4X128) read operations to cycle the clock and load the 128 bits of the shift register.

Descriptors :   *INTERRUPTION, *CONTROL SYSTEMS, *ELECTRIC SWITCHES, CYCLES, INPUT, INTERFACES, MICROCOMPUTERS, MONITORS, MODULAR CONSTRUCTION, SHIFT REGISTERS, INPUT OUTPUT PROCESSING, MICROPROCESSORS, SCANNERS, ELECTRIC CONTACTS

Subject Categories : Electrical and Electronic Equipment
      Computer Hardware

Distribution Statement : APPROVED FOR PUBLIC RELEASE