Path: utzoo!utgpu!water!watmath!clyde!cbosgd!ihnp4!inuxc!iuvax!pur-ee!uiucdcs!uiucdcsp!gillies
From: gillies@uiucdcsp.cs.uiuc.edu
Newsgroups: comp.sys.mac
Subject: Re: Will DMA ever be used in the Mac?
Message-ID: <76000065@uiucdcsp>
Date: 11 Dec 87 18:27:00 GMT
References: <5094@iuvax.UUCP>
Lines: 31
Nf-ID: #R:iuvax.UUCP:5094:uiucdcsp:76000065:000:1583
Nf-From: uiucdcsp.cs.uiuc.edu!gillies    Dec 11 12:27:00 1987


Here are some (possible) reasons why you won't see sophisticated DMA
devices or more distributed (outboard graphics) processing on an Apple
PC in the near future:

(1) Apple wants all its peripherals to work with all its computers.
This vastly simplifies marketing for Apple's peripherals.  Apple is
moving even farther in this direction, by standardizing the ADB bus,
therefore standardizing keyboard, mouse, and graphics tablet
interfaces.  Apple has settled on SCSI so that all its disks will be
hardware interchangeable.  So when you sell (or junk) that Macintosh
128 and buy a Mac II, you don't have to throw away that disk drive OR
modem.

(2) Apple does everything in software, possibly because of a holdover
philosophy from Xerox.  Xerox does everyhing in software--microcode!
There are very good reasons for this, especially if you're trying to
do a state-of-the-art product.  When you release a product, if there's
a serious bug, you can *ALWAYS* provide a software patch (unless the
bug is in the early part of system startup, like the Mac II Nubus 1Mb
bug).  Then, at worst, you can provide new ROMS.  Bugs in software are:
	(1) Easier to diagnose & fix
	(2) Faster to fix (replace a ROM or release new system/finder)
	(3) Therefore, Cheaper to fix.
Why do you think CRAY Computer corp *REFUSES* to design
state-of-the-art supercomputers in custom or unproven circuit
technologies?  When you try to do a state-of-the-art system, it is
important to have some stable ground to stand on.

Don Gillies {ihnp4!uiucdcs!gillies} U of Illinois
            {gillies@p.cs.uiuc.edu}