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From: bandy@amdcad.AMD.COM (Andy Beals)
Newsgroups: comp.unix.wizards
Subject: Re: tar (why a swab option?)
Message-ID: <16887@amdcad.AMD.COM>
Date: Fri, 29-May-87 14:16:13 EDT
Article-I.D.: amdcad.16887
Posted: Fri May 29 14:16:13 1987
Date-Received: Sun, 31-May-87 07:48:35 EDT
References: <1003@bobkat.UUCP>
Reply-To: bandy@amdcad.UUCP (Andy Beals)
Distribution: na
Organization: Advanced Micro Devices, Inc., Sunnyvale, Ca.
Lines: 39
Summary: Some computers are brain-damaged

In article <1003@bobkat.UUCP> m5@bobkat.UUCP (Mike McNally (Man from Mars)) writes:
>What's the point of the 's' (swap bytes) option to tar?  Are there any
>systems which store characters of a string in byte-swapped order (so
>"TAMALE" looks like "ATAMEL")?  I dig the scene with integers, man, but
>strings?  Far out.  Especially since it swaps bytes in the header
>blocks as well as in the data.

Well, I don't know what version of tar you're using (I checked both our UTS
and 4.3 systems), becuase I've never heard of that option before, but I think
that it is a useful one.

When I came here to work at AMD, I found out that not everyone who can design
a 1/2" tape interface can get the bytes in the right order.  Some time in the
deep dark past, AMD chose Valid as their workstation to pass out to chip
design teams.  They didn't notice anything funny then, but once AMD started
hooking all the workstations together with tcp/ip, they noticed that the file
format for all of the data files had the bytes swapped!  Also, if you do 
	(cd $src ; tar crf - .) | rsh destmach "(cd $dest ; tar xfB -)"
it wouldn't work.  If you ftp over a big tar file it won't work either.  But
if you say
	dd if=big.tar.file conv=swab | tar xf -
It works just fine.

So what happened here?  The people who designed their magtape interface got
the bytes backwards.  And what happened then?  The PINHEADS at Valid didn't
put a swab down in the driver or simply switch the wires coming out of the
interface, THEY PUT A SWAB INTO EVERY SINGLE PROGRAM THAT USED DATA FROM
MAGTAPE! 

When I heard that, I couldn't believe it; who could be so pinheaded?  But it
is true and every time I go and write another utility, I have to have it peek
aroudn the system to see if it's running on one of those damnable Valids and
put swabs in.

ICK.

Now we're "upgrading" to apollos, bu the valids will still be around.
-- 
Andrew Scott Beals, {lll-crg,decwrl,allegra}!amdcad!bandy +1 408 749 3683