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From: woody@tybalt.caltech.edu (William Edward Woody)
Newsgroups: comp.sys.mac.programmer,comp.sys.mac.system
Subject: Re: Developing software for ancient Macs
Message-ID: <1990Oct18.022850.17300@nntp-server.caltech.edu>
Date: 18 Oct 90 02:28:50 GMT
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In article <3635@syma.sussex.ac.uk> paulr@syma.sussex.ac.uk (Paul T Russell) writes:
>I have an 'interesting' problem. I need to write some
>software which will run on an original Mac 512 (well,
>over 100 of them actually, which is why it's not possible
>to upgrade to something newer). The application must reside
>on the (400k MFS) system disk and everything must obviously
>fit into 512k RAM. So what I need to know is:

	Gosh, I thought I was the only one that did this!

>1 What version of system software should I use ? I have all
>  of them on a CD-ROM but I'm not sure which one is the
>  newest usable version for a Mac 512.

	I think the version just before V5.0 will do it; I don't know offhand
which one that is, but I do remember Apple suggesting that v5.0 was the one
for a Mac 512Ke (which is what I'm running).

>2 The application will probably have to be written in Pascal.
>  Obviously I can use a slightly more modern Mac for development,
>  but will THINK Pascal (or any other Pascal compiler) generate
>  code which will run OK on these antique machines ? I seem
>  to remember some changes to do with the Segment Loader and
>  attributes on CODE resources when the Mac Plus came along...

	Yep.  The changes had to do with CODE resources being larger than 32K.
Just don't develop CODE resources larger than 32K; pure and simple.  I don't
know how THINK Pascal works, but under MPW you have to ask the linker to
produce code resources that won't work; by default the MPW linker produces
correct code for the old (64K) ROMS.

>3 Is there anything else which I might have problems with ?
>  Obviously I won't be able to use anything more recent
>  than Inside Mac I to III, but is there anything else
>  which might cause problems ?

	Nope; that should just about do it.  If you have all of the 'tech notes,
you can skim the ones about developing for HFS vs MFS, and checking the
environment you're running under for features being available.  The best
thing to do is to go ahead and use WaitNextEvent if it's present (so your
program will run properly under Multifinder in the background, if so desirable),
and as little else as you can get away with.

	I have written applications which will use color and multifinder and
all sorts of other gadgets on a Mac II and better, and still run on an
original 512K machine; it's really very simple, as Apple (god bless them!) have
made all the Macintoshes compatable from the original 128K through to the
Mac IIsi and IIfx.

	Good luck.
--
	William Edward Woody		   | Disclamer:
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