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From: fred@pnet01.cts.com (Fred Brooks)
Newsgroups: comp.sys.atari.st
Subject: Re: null fill eliminated
Message-ID: <3070@crash.cts.com>
Date: 4 Jun 88 13:56:10 GMT
Article-I.D.: crash.3070
Sender: news@crash.cts.com
Organization: People-Net [pnet01], El Cajon CA
Lines: 37

,
apratt@atari.UUCP (Allan Pratt) writes:
>From article <490@philmds.UUCP>, by leo@philmds.UUCP (Leo de Wit):
>> null fill (there could be a 1/(vbls/sec) delay %-) and is guaranteed NOT to 
>> work on all ROM versions 8-).
>> The main problem will be the addresses (start, end) of the fill-routine
>> in ROM. 
>
>
>This is appalling! Please get over the idea that you can fool with stuff
>in ROM.  For starters, some programs EXPECT that the whole heap (not
>just the declared BSS) is zeroed at startup...  Microsoft Write is one. 
>Maybe the disk cache you use, or the hard disk compaction utility, or
>something equally deadly expects this -- and you'll learn the hard way
>not to fool with this kind of thing.
>
>I know the clearing takes a long time on 11/20 ROMs.  It's much faster
>in Mega and future ROMs.  But it's still there, because it is a "settled
>expectation" among developers.  ("Settled expectations" are things that
>people count on despite the fact that nobody promised they'd stay true.)
>
>I urge people not to use this trick or any other which changes the
>environment that programs execute in, or depends so heavily on actual
>addresses in ROM. 
>
>============================================
>Opinions expressed above do not necessarily	-- Allan Pratt, Atari Corp.
>reflect those of Atari Corp. or anyone else.	  ...ames!atari!apratt

Why not make it an official then? "Settled expectations" are a hell of a way
to make programming specs. All of the programming languages say don't count
on space in the heap being zero or variables being set to any value before
being init'ed.

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