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From: apratt@atari.UUCP (Allan Pratt)
Newsgroups: comp.sys.atari.st
Subject: Call for opinions
Message-ID: <2059@atari.UUCP>
Date: 28 Feb 90 20:03:25 GMT
Organization: Atari Corp., Sunnyvale CA
Lines: 35

Without going into the gory details, I want to know what you
programmers out there think of adding the following constraint to
programming on the ST line of machines:

    "You must leave Timer C in the MFP as it was originally programmed."

This does not mean you have to leave its interrupt enabled, or its
interrupt vector pointing at the 200Hz handler: it just means you can't
reprogram that timer's control or data registers.

If you violate this constraint, or if you think it's unreasonable,
please let me know.  The point is that I need a way to count small
increments of real time, and I want to get rid of all the places where
instruction execution time is used to achieve a delay.

If accepted, violating this constrait results in Bconout to printer or
IKBD not working, and the floppy disk code not working reliably.

I'm trying to make this as transparent as possible: only really screwy
programs (games, demos, etc.) care about this stuff.  Timer C is the
system heartbeat, and you shouldn't mess with it unless you really feel
you need to, and then you should accept the consequences.

(It is already the case that revectoring or changing Timer C causes
GEMDOS to lose track of the time, and AES events not to happen, among
other things.  Also, incidentally, if you inhibit the system vblank
handler, floppy operations will never time out, and the floppy's access
light will never go out even on successful operations; the motor will
shut off, though.)

I don't want to make this decision in a vacuum.  What do you all think?

============================================
Opinions expressed above do not necessarily	-- Allan Pratt, Atari Corp.
reflect those of Atari Corp. or anyone else.	  ...ames!atari!apratt