Path: utzoo!attcan!uunet!ncrlnk!ncr-sd!hp-sdd!hplabs!pyramid!claris!krazy
From: krazy@claris.com (Jeff Erickson)
Newsgroups: comp.sys.apple
Subject: Re: Border color
Message-ID: <9105@claris.com>
Date: 20 Mar 89 06:01:54 GMT
References: <8903181756.AA05520@crash.cts.com>
Organization: Claris Corporation, Mountain View CA
Lines: 22

From by mdavis@pro-sol.cts.com (Morgan Davis):
> Dan Bornstein describes the method by which one changes the border color
> register on the IIGS.  You have to be careful with the upper nibble in this
> register because it is used by the Real Time Clock (RTC).  However, Dan's
> example showed 16-bit memory access being made to the $E0Cxxx area.  Is it not
> unsafe to do this?  When you fetch 16 bits from a location here you could
> possibly be hitting a softswitch.  I think it might be better to drop into
> 8-bit accumulator mode when working in the peripheral RAM area.

I've never, never, never had any problems with the smattering of code I
posted, and I used it for over two years.  No, I don't think its a problem.
The rest of that word doesn't contain soft switches like $E0C030 does.
(That's the speaker, isn't it?)  I don't remember the details, and I don't
have the manulas any more, but you can find out for sure in _The Apple 
IIgs Firmware Reference Manual_ (Addison-Wesley -- one of the GS Developer's
Bibles).

-- 
Jeff Erickson     \  Internet: krazy@claris.com          AppleLink: Erickson4
Claris Corporation \      UUCP: {ames,apple,portal,sun,voder}!claris!krazy
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____________________/        "I'm so heppy I'm mizzabil!" -- Krazy Kat