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From: joe@hanauma.stanford.edu (Joe Dellinger)
Newsgroups: comp.sys.apple2
Subject: Disk timing (was Re: Mega II (was: Accepting the Mac))
Message-ID: <429@helens.Stanford.EDU>
Date: 19 Mar 90 08:09:44 GMT
References: <1848@crash.cts.com> <18491@boulder.Colorado.EDU> <12667@thorin.cs.unc.edu> <39559@apple.Apple.COM> <1990Mar17.112032.18 <1990Mar18.095408.1765@spectre.ccsf.caltech.edu> <90077.155936JLS139@psuvm.psu.edu>
Sender: news@helens.Stanford.EDU
Reply-To: joe@hanauma.stanford.edu (Joe Dellinger)
Organization: Stanford University, Dept. of Geophysics
Lines: 20

In article <90077.155936JLS139@psuvm.psu.edu> JLS139@psuvm.psu.edu (Abaddon) writes:
>In article <1990Mar18.095408.1765@spectre.ccsf.caltech.edu>,
>toddpw@tybalt.caltech.edu (Todd P. Whitesel) says:
>
>    Correct me if I am wrong, but under DOS 3.3 wasn't disk access based
>in software (RAM) and wasn't writing based on critical timing loops.

Yes. The timing was so critical, in fact, that the position of some of DOS's
code relative to page boundaries MATTERED, because of the 1-cycle timing
difference that could make for some 6502 commands. Because of this, there
were some "holes" scattered through DOS 3.3 so that the critical hunks of
code would be properly aligned!

(PS: My Apple is so old that Prodos won't even boot on it. Anybody know why?
Doesn't matter to me, I keep my old Apple for its antique value these days.
It's a ][, not even a ][+ ...)
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