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Path: utzoo!linus!philabs!cmcl2!seismo!mcvax!boring!guido
From: guido@boring.UUCP
Newsgroups: net.micro.mac
Subject: Re: Use of command keys
Message-ID: <6445@boring.UUCP>
Date: Fri, 7-Jun-85 13:51:14 EDT
Article-I.D.: boring.6445
Posted: Fri Jun  7 13:51:14 1985
Date-Received: Wed, 12-Jun-85 00:58:45 EDT
References: <190@tmq.UUCP> <26700017@inmet.UUCP> <653@wanginst.UUCP>
Reply-To: guido@boring.UUCP (Guido van Rossum)
Organization: "Stamp Out BASIC" Committee, CWI, Amsterdam
Lines: 32
Apparently-To: rnews@mcvax.LOCAL


The problem with using the Option key as a control key lies in the keyboard
decoding.  Interpretation of the Option key is done deeply hidden in the
system file.  The Macintosh uses a 256-character set, of which the first
128 characters are the corresponding ASCII characters and the second 128
(well, three quarters of them) are used for "funny" characters like math
and foreign language symbols.  The keyboard decoding in the system file
uses a table which gives for every combination of shift, caps lock and
Option, what character out of the character set should be generated.
This table depends both on the keyboard you use (European keyboards
have a different lay-out and one extra key) and on the country you're
in (well, the country the mac thinks you're in).  You can change the
latter by software.  There is also software with which you can change
the map completely, but it depends on intricacies of the system code
that are not (*** yet ***) revealed in Inside Macintosh.

In contrast with this all, the Command key can be read out and interpreted
by any program.  For each character in the 256-character set that can be
generated from the keyboard, it can be determined whether the Command
key was pressed with it or not (some programs choose to ignore this fact!).

So this is probably the reason why all terminal emulators use the Command
key as a control key.  They're right about it in that it does not make
any assumptions about your keyboard layout or how your system file
interprets the keys.

(With the remapping software you could define the Option key to transmit
the control characters.  Personally I like the idea most of using the
Caps Lock key -- it's much more in the "natural" place for a Control key.
But you have to break the clicking mechanism...)

	Guido van Rossum, "Stamp Out BASIC" Committee, CWI, Amsterdam
	guido@mcvax.UUCP