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Path: utzoo!watmath!clyde!burl!hou3c!hocda!houxm!ihnp4!alberta!calgary!ubc-vision!mprvaxa!tbray
From: tbray@mprvaxa.UUCP (Tim Bray)
Newsgroups: net.lang
Subject: bit ordering - war story
Message-ID: <591@mprvaxa.UUCP>
Date: Tue, 18-Sep-84 21:24:20 EDT
Article-I.D.: mprvaxa.591
Posted: Tue Sep 18 21:24:20 1984
Date-Received: Tue, 25-Sep-84 05:48:27 EDT
Organization: Microtel Pacific Research, Burnaby, B.C, Canada
Lines: 17

A coupla years back, there was this little engineering company that had
a decade's worth of financial records stored on tapes created by an IBM
1130 (a computer for real men), in binary floating point format.  They
had this shiny new VAX, and no data interchange facility.

Solution - a VAX assembler routine which takes an 1130 double precision
floating point number - six (6) bytes - and spits out the equivalent
VAX double precision datum.

Bit orders.  Hah. You think you know about bit orders.   Latent bits.
Middle-ender word ordering.  One's complement mantissas for negative
numbers - any idea what that does to negative powers of 2?

Of course, the auditors wet their collective pants when all the bottom
lines in the million-dollar plus items started being off by a few
pennies on the new computer.  Tim Bray {ihnp4!alberta,
decvax!microsoft} !ubc-vision!mprvaxa!tbray