From: mfrank@wilma.cs.wisc.edu (Matt Frank)
Subject: Re: What's in a name?
Organization: University of Wisconsin, Madison -- Computer Sciences Dept.
Date: Sat, 25 Jul 1992 07:51:30 GMT

In article <1992Jul20.103537.57342@cc.usu.edu>, ivie@cc.usu.edu (CP/M lives!)
writes:
>In article <1992Jul20.092822.7666@spool.cs.wisc.edu>,
>mfrank@wilma.cs.wisc.edu (Matt Frank) writes:
>>   Now, assume that Win/NT takes off and everyone buys it.  Will anyone buy
>> WordPerfect or 1-2-3 anymore?  NO, they'll buy something else (very likely
>> Microsoft Word and Microsoft Excel).  
>
>Not initially. It needs to run the old stuff long enough to convince people
>that it's going to take over the world. It takes time for software to ramp
>up and for the software guys to decide which platform to use. But the
>software guy's decisions are based on the hardware that's selling. People
>don't want to buy hardware that holds the _promise_ of eventually running
>useful software, they want to run useful software _today_. 

Both the Apple ][ and Mac are examples of non backwards compatible products
enjoying great success.  So are CD players.  Although it was before my time,
aren't CP/M, minicomputers, DB2 and UNIX other examples?

And in article <MKAHN.92Jul22092527@hopi.sedona.intel.com>,
mkahn@hopi.sedona.intel.com (Mitch Kahn) writes,
>] 1)  Backwards compatability is a waste of everyones time.
>
>Better tell that to DEC, IBM, MIPs, Motorola etc. as well as all the users
>in the world who do not want to buy new software every time they get a
>faster box. What color is the sky in your world?
>
>]
>] 2) Nobody ever uses the backwards compatable features anyway.
>
>You're right. I'm getting a new workstation this week and to celebrate
>I'm going out and buyin $10K worth of new (incompatible) software just
>because some technogeek decided incompatibility wasn't an issue. NOT

I said "BACKWARDS compatible" not "compatible".  In my original post I PRAISED
the idea of a faster 8086.  While I'm at it, I'll also praise the virtual 8086
mode on the 80386.  It was a great idea to allow users to multitask their 8086
sessions.  If people buy a computer, then I'm all for vendors coming out with
faster versions of it.

Nor was I intending to single out Intel for criticism.  I used Intel as an
example because the x86 is the chip I know best.  I've been an MS-DOS
programmer since 1987, and I own a 386 box.  I LIKE my PC-compatible computer.

What I WAS criticizing is that the NEW features in each generation of a
backwards compatible design are more complicated than they would have been
had those features been part of a new design.  In the case of processors,
customers coming over from the old design are winners (but they would have
stayed customers if the designers had just come out with a faster version of
the same chip.)

New customers might lose because:
A) the processor may be slower than a new design would have been, or
B) optimizing compilers and assembly code may be harder to write than they
would have been (so software is slower), or
C) they pay for new features that rarely or never get used because software
manufacturers won't take advantage of them (as is the case with MS-DOS).

To use a database example: IMS on the 370 had great staying power for years
because thousands of customers had a huge investment in applications and data.
When DB2 came out though, the advantages were so numerous that customers
started moving to it.  (Mostly they write new applications in it, and leave
the old applications in IMS until it comes time for a major rewrite).

(Perhaps even more interesting are the shops where they slowly replace all
their terminals with networked PCs running terminal emulators.  Then once
they have a PC on every desk they buy Oracle.)

Lots of companies have made lots of money, and stayed profitable, by
continuously coming up with innovative new ideas.  The argument that no one
will buy a fantastic new design unless it is backwards compatible, doesn't
wash.

If anyone wants to mail me other backwards compatability examples (pro or
con), I'll summarize.

-Matt Frank (mfrank@cs.wisc.edu)
My opinions are my own and may not be those of
Newsgroups: comp.arch