This is a more efficient switch scanning method for single- or multiple-switch users than a standard cell-by-cell scan.
Row/Column, sometimes known as Group, scanning allows a lot of cells to be grouped together to lessen the amount of time, or switch presses, required to reach a target key.
In the example keyboard shown it would take 35 switch-presses or scan 'delays' to reach the letter H. Once reached the user could press his or her switch to activitate it but by that time may have lost interest or have become too tired to continue.
By grouping the cells together the amount of switch-presses or scan delays required to reach the same letter is reduced to just 10. That's a big difference but you can make the process even more efficient by changing the layout of the keyboard to match the user's frequency of use.
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