Four wire keyboard interface
US4706068A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jan 30, 1985 |
| Grant date | Nov 10, 1987 |
| Priority date | — |
| Expiry date | Jan 30, 2005 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03M11/20
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A computer system comprises a terminal and a keyboard, the terminal comprises a central control unit for controlling the operation of the keyboard and the keyboard comprises a switch array, the switch array has a plurality of rows and a plurality of columns. The terminal further comprises a data output port for transmitting a command signal from the terminal central control unit and a data input port for receiving a data signal from the keyboard. The command signal comprises a keyboard initialize signal and a keyboard increment signal. The keyboard further comprises a four-wire keyboard interface for communicating with the terminal. The four-wire keyboard interface facilitates the initialization of a sequence for scanning the switch array after the receipt of the keyboard clear signal, the scanning of the switch array for detecting the activation of a location of the switch array after the receipt of the keyboard increment signal, and the transmission of the data signal after detecting the activation of the location of the switch array.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.