Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!think.com!sdd.hp.com!wuarchive!uunet!microsoft!jamesth
From: jamesth@microsoft.UUCP (James THIELE)
Newsgroups: comp.sys.mac.hypercard
Subject: Re: Old Xs and New System
Message-ID: <72831@microsoft.UUCP>
Date: 9 Jun 91 18:12:20 GMT
References: <1991Jun5.173936.2913@agate.berkeley.edu| <1991Jun5.220335.1466@guinness.idbsu.edu>
Reply-To: jamesth@microsoft.UUCP (James THIELE)
Organization: Microsoft Corp., Redmond WA
Lines: 30

In article <1991Jun5.220335.1466@guinness.idbsu.edu| bcarter@claven.idbsu.edu (Bruce Carter) writes:
|In article <1991Jun5.173936.2913@agate.berkeley.edu> jstern@garnet.berkeley.edu
|() writes:
|>Is anybody having problems with their existing stacks (with xcmds) running
|>under system 7? Somebody warned me that I don't want to switch to system 7
|>because differences in addressing could cause problems with some (many)
|>existing xcmds. (I've got 2 meg SEs and Pluses). Any truth to this? Should I
|>expect to have to find upgrades for the xcmds that I'm using?
|
|I think the greater amount of incompatibility would be between Xthings written
|for HyperCard 1.x versus 2.x rather than System 6 versus System 7.  I have read
|that Xthingies which manipulate windows are a potential trouble spot.  Thus
|far, we haven't had any problems, but we use a limited number of Xthings.

A specific problem between HC 1.x and 2.x involves Xthingies that do not return
allocated memory (2.x appears more sensitive in places) *especially* if
they memory came via NewPtr() rather than being a handle.  The left-over
pointers are particularly destructive if an attempt is made to increase
the card size - there may be no way to get a large enough contiguous
block to expand the card (I saw early 2.0 get fairly confused in this
situation).

You can test your Xthings for eating memory in a loop while reading
"the heapspace", checking whether it gets progressively smaller,
though it might get smaller the first couple times in any case as HC
shuffles in the Xthing.

Hope this helps,
James Thiele
microsoft!jamesth