Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!mnetor!seismo!think!husc6!husc4!hadeishi From: hadeishi@husc4.harvard.edu (mitsuharu hadeishi) Newsgroups: net.micro.amiga,net.micro.68k Subject: Re: The Motorola 68030 Message-ID: <321@husc6.HARVARD.EDU> Date: Sat, 4-Oct-86 14:31:28 EDT Article-I.D.: husc6.321 Posted: Sat Oct 4 14:31:28 1986 Date-Received: Mon, 6-Oct-86 18:45:15 EDT References: <2270@gitpyr.UUCP> <262@husc6.HARVARD.EDU> <877@Shasta.STANFORD.ED <3853@amdahl.UUCP> <1177@hoptoad.uucp> Sender: news@husc6.HARVARD.EDU Reply-To: hadeishi@husc4.UUCP (mitsuharu hadeishi) Organization: Harvard Science Center Lines: 61 Summary: More Motorola versus Intel Xref: mnetor net.micro.amiga:5082 net.micro.68k:1347 In article <1177@hoptoad.uucp> John Gilmore writes: >[==> Followups have been redirected to net.micro.68k <== If you care >about this topic, please start reading about it there. The mac/amiga/atari >users have enough to talk about without Intel/Motorola flames. I'm just glad >nobody has tried including net.micro.pc, then the flames would really start!] I don't have time to read another newsgroup, so I'm keeping this thread here. Sorry! >My impression is that the relative power of each chip relates strongly >to its design date. Thus, Motorola chips have tended to be more >powerful than the corresponding Intel chips, because they were designed >slightly later. The 80386 should be faster than the 68020, since it is >coming out about a year later. Agreed. >I'm not going to argue the merits of Intel versus Motorola. It is clear >to me that both have learned from each other. Now it is up to us, the >users, to learn to write our stuff portably so we can move it to the machine >of whoever is learning the fastest at each point in time. It is really not very easy to write portably for the two micro- processors, since they are such massively different architectures. If you're writing in a high-level language, then things are difficult because of the massive differences between MS-DOS and 68000-based operating systems. If you're willing to restrict yourself to character- screen oriented applications, then you might have a slim chance working completely in a high level environment (read: SLOW on an 8086.) I think the basic issue comes down to elegance. The Motorola designers decided to throw away the past when they came up with the 68000, and I think they made the right decision. Intel instead decided to sidle themselves with an endless nightmare of backward-compatibility. The 80386 operates, for example, on 32-bit objects when in native mode, and to get it to address words you have to switch to '286 emulation mode. (Although both address bytes with no problems.) The '386 has to have two emulation modes ('286 and 8086) in order for software to run properly; this makes the whole software engineering project all the more complicated. I feel sorry for the Intel designers in particular who have to put in all this extraneous crap to maintain compatibility. The 68000 series, on the other hand, is upward compatible with no need for emulation modes. (With the exception of MOVE SR,(ea)) 68000 code will run unmodified on a 68010 and a 68020. The only differences are in the interrupt exception handlers, and even this is not a problem because the 68020 will still be able to handle 68000-style interrupts without having to change the program code (only the exception handlers.) AmigaDOS/Intuition does this with no problems. The issue here is elegance as well as performance. It is much easier to take a large base of 68000 software and run it to full advantage on a 68020 because 68000 code is essentially written as though it were running on a true 32-bit machine. When it is run on a true 32-bit machine, it *really* blazes. The fact that the '020 and '030 need no "emulation modes" makes the upgrade path infinitely smoother; an MS-DOS task running under emulation mode on a 386 still has to deal with a 640K RAM limit, even if you're using virtual memory. This isn't really a serious limitation in most cases, but it is certainly ugly and to my mind unnecessarily complex and non-uniform. -Mitsu