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INTERRUPT DRIVEN 4 BY 4 KEYPAD Disclosure Number: IPCOM000005778D
Original Publication Date: 1989-Aug-01
Included in the Prior Art Database: 2001-Nov-06

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Frederick Cheah Teh Do Hui Boh Kai Chek


The design of a4 by 4 keypad can be approached by either adopting the serial or the parallel concept. The serial concept is tedious in terms of software effort, complex in circuitry and slow in response. However, it re- quires few interface lines. The parallel concept on the other hand is less complex in circuitry, IesS SoftWare intensive and faster in response The parallel concept also requires more interface lines, namely, 8 plus an interrupt line for a 4 by 4 keypad.