United States Patent
US Patent 5263171: Device for interfacing two keyboards to one…
US 5263171 · granted 1993-11-16
| Patent Number | 5263171 |
|---|---|
| Title | Device for interfacing two keyboards to one computer and for automatically connecting the active keyboard to the computer |
| Filed | 1990-03-27 |
| Granted | 1993-11-16 |
| Inventor(s) | Robert R. Asprey |
| Assignee | Cybex Corp |
| CPC Classification | G06F3/02, G06F3/00, G06F3/01 |
| Number of Claims | 2 |
Abstract
This invention pertains to circuitry for automatically coupling up to four keyboards to a single keyboard port of a computer. Switching is accomplished by sensing a clock pulse appearing on one of the keyboard clock pulse lines responsive to a keystroke appearing on one of the keyboards. The clock pulse is applied either to a set input or a reset input of a latch, depending from which of keyboard clock pulses lines the pulse originated. The set or reset condition of the latch evokes a selected voltage potential on the output of the latch, which biases “on” bi-directional switches, coupling one of the keyboards to the computer.
Claims Summary
1. A keyboard switching system comprising:a first bidirectional keyboard of a type which generates first keyboard clock signals and first keyboard data signals upon occurrence of a keystroke, and further having a first keyboard clock signal terminal for passing said first keyboard clock signals to a computer and for receiving computer signals from a computer, and having a first keyboard data signal terminal for passing data signals to and from a computer;