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From: fiddler%concertina@Sun.COM (Steve Hix)
Newsgroups: comp.sys.apple
Subject: Re: AppleFest 1987
Message-ID: <31973@sun.uucp>
Date: Mon, 26-Oct-87 15:02:55 EST
Article-I.D.: sun.31973
Posted: Mon Oct 26 15:02:55 1987
Date-Received: Thu, 29-Oct-87 06:30:24 EST
References: <953@percival.UUCP>
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In article <953@percival.UUCP>, gronke@percival.UUCP (Lisa Gronke) writes:
>  
> The Zip Chip by Zip Technolgies is a pin compatable chip that replaces the
> 65c02 in your IIe or IIc. Once installed your machine will run at a full 
> 4 meghertz speed.
>  
Sounds fascinating.  How do they deal with time-critical software
timing loops (such as reading the Disk][ in ProDos and Sloth3.3)?

Apple got around the problem by slowing the clock whenever the one
of the disk signal lines (I forget which) was asserted.  This has
the side effect of slowing the effective clock speed to some lesser
value than the maximum.

Do they also change the system clock rate?  How do they keep from
mucking up the screen clocking stuff?  I'd love to see this,
especially if it works more or less transparently.

	seh