22 Jan
2012
22 Jan
'12
2:32 p.m.
On 22 Jan 2012 at 11:08, Eric Smith wrote:
Chuck Guzis wrote:
The sentence before the one quoted said "good keyboards". "Many", I
suppose is subjective--"n-key-rollover" was touted more on older
systems than on $10 keyboards offered today. Keytronics used to
advertise it heavily on their high-end keyboards. The Toshiba
luggable laptops (3000 and 5000 series) all featured n-key rollover.
Perhaps, given the large number of keys on a modern keyboard (other
than laptops), careful distribution of keys minimizes the effect of
ghosting.
Six-key rollover seems to be a good compromise; I suspect the most
anyone sees in the real world is 3 or 4 key.
Or perhaps today's crop of keyboardists never learned to type on a
typewriter.
--Chuck
But many PC keyboards implement [n key rollover]
also.
I wouldn't say "many", as it was always a small fraction. The
vast
majority did not have diodes or any other technique to prevent
ghosting, and only offered two key rollover, which is generally
satisfactory for most typists. It was common for some of the
"special" keys (shift, control, alt) to not be part of the scanned
matrix, so you could detect any number of those, but not reliably
detect more than two "normal" keys at once.