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From: tecot@apple.UUCP (Ed Tecot)
Newsgroups: comp.sys.mac
Subject: Re: KMAPs and KCHRs
Message-ID: <6500@apple.UUCP>
Date: Sun, 18-Oct-87 20:20:17 EDT
Article-I.D.: apple.6500
Posted: Sun Oct 18 20:20:17 1987
Date-Received: Tue, 20-Oct-87 00:37:41 EDT
References: <3022@crcge1.UUCP>
Reply-To: tecot@apple.UUCP (Ed Tecot)
Organization: Apple Computer Inc., Cupertino, USA
Lines: 40
Keywords: Keyboards

In article <3022@crcge1.UUCP> ranson@crcge1.UUCP (D. Ranson CNET) writes:
>
>(Before you ask: Yes, I have read TechNote 160)

Good.  Please note that the following information describes System 4.1 and
later ONLY.

> How are KMAP ressource REALLY used in System4.1? On a SE, I have found that
>KMAP ID 1 in the System file is actually used (You can easily swap 2 keys),
>but the Keyboard DA apparently assume a default KMAP.
>On a Plus, KMAPs seem to have no effect at all. You can boot from a System4.1
>without any KMAP in it! Are KMAPs only for ADB keyboards? Why this limitation?
>I suppose the right KMAP is chosen at boot time by comparing some sort of
>keyboard ID to the ressource ID. Any info on that?

The KMAP is used to convert the raw keycodes from any ADB keyboard to the
"Virtual" keycode set which is defined to be a superset of the MacPlus
keyboard codes, thus eliminating the need for a KMAP for non-ADB machines.
The code checks for a KMAP that matches the handler ID of the keyboard in
question and uses it.  If one is not found, it uses KMAP 0 (found in ROM).
The code was not extended to the MacPlus for several reasons:
1) The code and space required for the KMAP would cramp an already overcrowded
	system heap.
2) It would break just about any upgrade (Radius, Prodigy, GCC)
3) It is really not necessary (see below)

>We French Mac-ers are particularly interested in KMAPs because of a bug in
>the "physical mapping" of our keyboards. The raw codes for the keys < and `
>have been swapped between the Plus and the ADB keyboards. Only KMAPs can cure
>that if you want a universal System file (Currently, the recommended System
>file for a Plus in France is 3.2).

You don't want to modify the KMAP since KMAPs are not meant to be localized.
They are intended to be universal across all systems for a particular
keyboard.  KCHRs are, on the other hand localizable.  However, I do understand
your problem and realize that fixing the KCHR would not solve your problem.
Never fear, though; even as we speak, the problem is being fixed, I recommend
that you contact your local Apple Sales office.

						_emt