🚀 go-pugleaf

In article <2eb4edac@ralf>, Ralf Brown <ralf@telerama.lm.com> says:
>
>I just tried it on my AnyKey, and found:
>     <left-shift> <f> <t>    fails on the 't'
>     <left-shift> <g> <t>    fails
>     <f> <left-shift> <t>    fails
>     <g> <left-shift> <t>    fails
>     <left-control> <f> <t>  fails on the 't'
>     <f> <left-control> <t>  fails
>     <left-control> <g> <t>  fails
>     <g> <left-control> <t>  fails
>but
>     <right-shift> <f> <t>   works
>     <f> <right-shift> <t>   works
>     <right-ctrl> <f> <t>    works
>     etc.

The AnyKey keyboard is a hard contact keyboard.  This means it is layed out in a 
matrix, with each key at the junction of an x and y matrix line.  When you press 
a key, the keyboard firmware sees one x line and one y line as being active, so
it can tell what key is pressed.  When you press more than one key, it can usually 
tell which key is pressed, except for one special circumstance: when you press 
three keys and the keys form three corners of a rectangle in the matrix.  When 
this happens, the firmware can't tell if those three were pressed, or if the 
key at the forth corner was pressed.  This is called a phantom, and most keyboards 
will send an 'ff' code to signal that condition.  To get around this situation, 
most keyboard manufacturers take great pains to lay out the matrix so that a 
phantom will occur for only the most unusual of key combinations.

If the AnyKey phantoms on such simple combinations as left shift-f-t, then the matrix 
is very poorly layed out.  Thanks for the ammunition.<G>

By the way, a capacitive keyboard does not phantom at all.  You can press up to 
eight keys at once, and the computer will see all eight scan codes.

        Mike Burton
        Senior Software Engineer
        Key Tronic Corp. (one guess what we make<BG>)