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From: mrc@Tomobiki-Cho.CAC.Washington.EDU (Mark Crispin)
Newsgroups: comp.arch
Subject: Re: RISC hard to program?
Message-ID: <5071@milton.u.washington.edu>
Date: 14 Jul 90 01:16:10 GMT
References: <40088@mips.mips.COM> <2162@opus.cs.mcgill.ca> <1139@carol.fwi.uva.nl> <9895@pt.cs.cmu.edu>
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In article <9895@pt.cs.cmu.edu> lindsay@MATHOM.GANDALF.CS.CMU.EDU (Donald Lindsay) writes:
>In article <1139@carol.fwi.uva.nl> beemster@fwi.uva.nl 
>	(Marcel Beemster) writes:
>>In general my feelings towards
>>software development are: "If it runs on s SPARC, it runs everywhere",
>
>It's good for portability to develop code on the _least_ forgiving
>machine that you can find.
>
>I once did it the other way around, to my sorrow.  We had a large
>compiler that ran on a DEC-20, and was supposedly working.  I ported
>it to a VAX with BSD 4.2, and there were no end of seg faults.
>Then I ported it from the VAX to a Sun-3.  Another disaster!

My experience with porting code between DEC-20, VAX BSD 4.3, Sun-3,
NeXT, Sun-4, DEC RISC, Macintosh, MS-DOS, and Sequent suggests that
all of these systems are "unforgiving" in their own unique ways.  The
DEC-20 will nail you if you think that bytes are in any way related to
the unit of addressing or if you think you know in what direction the
stack grows.  MS-DOS will nail you if you think that pointers will fit
inside an int or if you use strings larger than 64K.  Macintosh will
nail you on 64K limits and memory management too -- malloc()/free() is
not how you want to use memory on a Mac.  VAXen and other
little-endian machines will nail you if you think that a 16-bit
quantity can be copied to a pair of bytes.  And so on.

It seems to me that using an ANSI compiler and ANSI-style prototyping
saves an amazing amount of time, more than initially developing on any
particular architecture.
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