Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Posting-Version: version B 2.10 5/3/83; site micomvax.UUCP
Path: utzoo!linus!philabs!micomvax!ottmar
From: ottmar@micomvax.UUCP
Newsgroups: net.micro.6809
Subject: RE: Review of HJL-57COCO Keyboard
Message-ID: <215@micomvax.UUCP>
Date: Mon, 17-Oct-83 13:27:14 EDT
Article-I.D.: micomvax.215
Posted: Mon Oct 17 13:27:14 1983
Date-Received: Tue, 18-Oct-83 20:21:57 EDT
Organization: Micom, Montreal
Lines: 23

I found the review useful and informative. However, there is one minor
point that I would like to dispute: the N-key rollover.

*NOTE* since no mention was made of hardware/software modifications, I assume
       that it is a "drop-in" replacement for the original keyboard.

The Color Computer does NOT receive data from the keyboard as a stream of
characters. It can only determine which keys are instantaneously depressed
at any given time. Therefore, the software must continually poll the keyboard,
debounce the keys, etc. Since the interface is constructed this way, N-key
rollover is a function of the SOFTWARE, not the hardware. It is a contradiction
in terms to discuss "N-key rollover" as an attribute of a CoCo-type keyboard.

The bottom line is this: the Mark Data keyboard "has" N-key rollover in the
same way that the other two keyboards do (i.e. when attached to SOFTWARE that
can perform this function). However, Mark Data is being much more careful in
its advertising to avoid misleading the consumer. The other two companies are
perhaps not overly concerned with this aspect of their ads, and would rather
have the "N-key rollover" buzzword present, even though it is IRRELEVANT to
their keyboard implementation.

						Ottmar Bochardt
						...!philabs!micomvax!ottmar