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From: olson@endor.harvard.edu (Eric Olson)
Newsgroups: comp.sys.mac
Subject: Re: Should we support 64K ROMs anymore?
Message-ID: <815@husc6.UUCP>
Date: Wed, 3-Dec-86 13:02:57 EST
Article-I.D.: husc6.815
Posted: Wed Dec  3 13:02:57 1986
Date-Received: Wed, 3-Dec-86 21:54:03 EST
References: <385@runx.OZ> <1366@hoptoad.uucp> <342@apple.UUCP> <4372@ut-ngp.UUCP>
Sender: news@husc6.UUCP
Reply-To: olson@endor.UUCP (Eric Olson)
Organization: Aiken Computation Lab, Harvard University
Lines: 44

In article <4372@ut-ngp.UUCP> werner@ut-ngp.UUCP (Werner Uhrig) writes:
>In article <342@apple.UUCP>, dgold@apple.UUCP (David Goldsmith) writes:
>> In article <1366@hoptoad.uucp> tim@hoptoad.UUCP (Tim Maroney) writes:
>> > [ gripes about various things - possibly justified 
>> You are welcome to try this; however, you will find that 50% of the existing
>> applications break, because they rely on features of the ROM above and
>> beyond those documented in IM, including those which are not "features"
>> but actually implementation details.  Many commercial applications:
>>	[ mostly interesting and probably valid points ]
>
>when I first saw IM I threw it into a corner and decided that it was suicidal
>to even try to develop software based on "that mess" - anyone who did has
>my deepest admiration (and sympathies).  For many types of applications I
>suspect that it was nearly impossible to get things done without going beyond
>what IM told the developer about.  I think it is unfair to make it sound as
>if all developers had to do was to "follow the IM-guidelines", I suspect.
>
>am I terribly off the track with such "heresy"?

Yes (my opinion, of course).  In fact, since you through it into a corner
and presumably the Mac User Interface with it, you didn't give it a chance.
I've spent the last year writing some of the weirdest code I've ever written
for any machine, code that breaks all the rules, and yet it still runs on
every configuration of the Macintosh, including any kind of disk, memory
size, processor (68000 or 020), and I have a high degree of confidence that
it will continue to run on virtually all future architectures.

It's worth pointing out, however, that code that I wrote 2 years ago for
the Mac doesn't work, the reason being the I WROTE IT WRONG.  I used TRAP
instructions to get into supervisor mode (I now know that the Mac is always
in supervisor mode).  I hard-coded the address of the serial chip (which
is available in lo-mem global SCCBase) [If you're wondering why I didn't
use system software to access the SCC, I was reading at 500KBaud].  I
compiled some code with SUMacC (which doesn't run on a Prodigy 4 - don't
know why).

The point being that there ARE correct ways to do these things.  I just
didn't know them.  And I won't take al the blame, either-- this was when
Inside Mac was changing every month (I have a very old chapter that talks
about triple clicking!).  So it's to be expected that some things won't be
right in implementation, but I firmly believe that the OS/Toolbox provides
a correct way to do most anything.

-Eric