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From: lsr@Apple.COM (Larry Rosenstein)
Newsgroups: comp.sys.mac.programmer
Subject: Re: Tail patches
Message-ID: <5268@internal.Apple.COM>
Date: 18 Nov 89 00:56:12 GMT
Article-I.D.: internal.5268
Sender: usenet@Apple.COM
Organization: Objects-R-Us,  Apple Computer, Inc.
Lines: 42
References:<5212@internal.Apple.COM> <32982@mirror.UUCP> <9010@hoptoad.uucp>

In article <9010@hoptoad.uucp> tim@hoptoad.uucp (Tim Maroney) writes:

> The amount of extra RAM that would be required for Apple to do its ROM
> patches without breaking tail patches is not all that large; perhaps
> 64K above the amount of patches in place now.  We're about to enter a
> year when 2M will be the standard amount of RAM on a Mac, and 64K is

64K sounds like a reasonable guess, given that the typical ROM has 256K 
total.  It is not clear to me that an extra 64K of RAM patches and disk 
space is acceptable.  People are already concerned that System 7 will 
require 2Mb.

Also, there probably will be users who do not choose to use System 7 
because it requires 2Mb.  Those users will continue to have come-from 
patches, which mean tail patches won't be guaranteed to work on those 
machines.  

I think the key point is not how much memory is required, but whether 
allowing tail patches is reall a boon to the Macintosh user.  

> It would also be nice if Apple would make new ROMs widely available.
> That would be a complete solution to the problem.  ROMs are easier
> to change than SIMMs, after all.

In practice, it is expensive for Apple to offer a ROM upgrade.  Plus, it 
only changes the problem; there are always going to be ROM bugs, and RAM 
patches for those bugs.  Plus it just gives developer several more 
hardware configurations to worry about.

> time, I have yet to see any problem with the software that results from
> its tail patching of the Fill routines.  So remember -- tail patching
> is a risk, but depending on what you're doing, it may be an acceptable
> risk.

Correct.


Larry Rosenstein, Apple Computer, Inc.
Object Specialist

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