Path: utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!sun-barr!newstop!texsun!convex!swarren
From: swarren@convex.com (Steve Warren)
Newsgroups: comp.arch
Subject: Re: IBM RISC
Message-ID: <100147@convex.convex.com>
Date: 21 Feb 90 18:36:21 GMT
References: <9376@portia.Stanford.EDU> <E58.+d@cs.psu.edu>
Sender: news@convex.com
Organization: Convex Computer Corporation; Richardson, TX
Lines: 45

In article <E58.+d@cs.psu.edu> schwartz@barad-dur.endor.cs.psu.edu (Scott E. Schwartz) writes:
>In article <9376@portia.Stanford.EDU> Dwight Joe writes:
>>So, does Sun launch that new architecture, say ARX, to compete
>>against the IBM 6000?  ....
>>If the answer is "no" (we don't incorporate upward compatibility),
>>then Sun LOSES.  The new Sun competitor against the IBM 6000
>>won't have ANY software adantage, which would be crucial in
>>the highly competitive marketplace.  
>
>I don't understand your claim here.  In this day and age porting an
>application (other than a compiler of some sort) to a new architecture
>(at least in the Unix world) usually involves typing "cc *.c".  The
                              [...]
Well, some disadvantages to loosing binary compatibility that come to
mind are,

1)  Rewrite the compiler (instead of re-optimizing the same compiler),
    which is added expense/time.

2)  Convince software venders to port to the new architecture.  Admittedly
    this should not be too bad if they have been successful with the
    previous architecture.  But any vendors who are disappointed with
    sales may not want to port.  And they are unlikely to provide the
    source code to individuals.  Even an unpopular application might
    make or break a few sales to specific niche customers.

3)  Risk the dissappointment of past customers who realise that new
    software will not be available for their (now) obsolete machines.
    The applications may slack off gradually, but the trend starts when
    the old architecture goes out of production.  (This is something
    that every customer has to face eventually, but the longer the
    manufacturer holds it off while remaining competitive, the happier
    his customer base is going to be.)  Naturally, upward compatibility
    does not imply downward compatibility.

4)  Customers with mixed machines will need duplicate partitions with
    appropriate copies of all their executables. 

Of course if the price/performance boost is high enough then it will
outway these dissadvantages.

--
--Steve
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