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From: darin@ut-dillo.UUCP (Darin Adler)
Newsgroups: net.micro.mac
Subject: Re: Delphi Mac Digest V2 #14 (pigs and ROMs)
Message-ID: <177@ut-dillo.UUCP>
Date: Tue, 15-Apr-86 04:59:32 EST
Article-I.D.: ut-dillo.177
Posted: Tue Apr 15 04:59:32 1986
Date-Received: Thu, 17-Apr-86 00:41:34 EST
References: <4762@topaz.RUTGERS.EDU>
Organization: University of Texas, Austin
Lines: 27
Keywords: Delphi
Summary: What "Pig Mode" really is.  64K ROM versions.

In the Delphi Digest:
> According to Steve Costa of BMUG, Pig Mode is a heap fragmenter designed to
> reveal errors in ResEdit.  Makes the program run a bit slow, naturally, since
> stuff is being moved around in the heap a lot.

Flipping Pig Mode is precisely this:  once every time through the main event
loop of ResEdit the following calls are made:

	PurgeMem(maxBlock);
	CompactMem(maxBlock);

This has some effects similar to heap scramble (moves blocks around a lot).
I seem to recall that it was mentioned as a recommended debugging practice
by one of the tech notes.

> (Discussion about different ROM versions)

> I note that Inside Mac is based on ROM version "105" which corresponds to the
> 69(hex) ROM version number we found in our Mac 512K's 64K ROMs at 400008.

As I mentioned in an earlier posting about versions, the current System
file (3.0 and up) uses the ROM version number to decide which set of patches
to use.  It only recognizes three versions:  105 ($69, 64K ROMs), 118 ($76,
128K ROMs), 28927 ($70FF, Latest? MacWorks).  Thus, I think that it is
unlikely that ROMs with other versions are common.
-- 
Darin Adler	...!ut-sally!ut-ngp!ut-dillo!darin