Date: Thu, 26 Jan 95 09:00:43 +0100
From: thomas AT moli DOT bph DOT ruhr-uni-bochum DOT de (Thomas Rink)
Apparently-To: djgpp AT sun DOT soe DOT clarkson DOT edu

Dear DJGPP people,

this week I have been compiling the GROMSD molecular dynamics program
using f2c and gcc on an i486 PC (HP Vectra VL2 486DX2/66) under MSDOS 6.22. 
While the first tests without optimization ran just fine (about three times 
faster than on an SGI IRIS workstation), I encountered a problem which 
seems to be related to optimization. When compiling with the switches 
"-fforce-mem" or "-ffast-math", the program fails to write an output file.
MSDOS then reports a fatal error like "sector not found" and the FAT is 
usually corrupted after aborting the operation. With "-ffast-math", even
the hard disk's Master Boot Block was destroyed ;-(. The PC has a 540 MB
IDE harddisk with a single primary DOS partition (4096 Bytes cluster size).
Writing the output file was forced by command line redirection of stdout
as the program's output normally goes to stdout.
Have bugs of this kind already been reported? If you have an idea about
what could have caused the trouble I'd be grateful to hear about it.
My address is

        Thomas Rink
        Department of Biophysics
        Ruhr-Universitaet Bochum
        D-44780 Bochum
        Germany
email: thomas AT bph DOT ruhr-uni-bochum DOT de