IBM floppy drives (fwd)

[chan4@husc.harvard.edu (Derek V. Chan)]

Hi all!   Just came upon some info. on the TP 750C & Linux!  I'll try this 
out and let you all know about this asap!

Later.


-- Derek





>From: xxxxxxxx@husc
>Subject: IBM floppy drives (fwd)
>To: chan4 (Derek Chan)
>Date: Sat, 2 Apr 1994 13:38:52 -0500 (EST)
>Content-Length: 1902      
>
>Forwarded message:
>>From xxxxxxxx@husc Sat Apr  2 04:17:29 1994
>Date: Sat, 2 Apr 94 04:17:24 -0500
>From: xxxxxxxx@husc
>To: xxxxxx
>Subject: IBM floppy drives (fwd)
>Organization: Evil Geniuses for a Better Yesterday Afternoon
>
>
>Newsgroups: comp.os.linux.misc
>Subject: ThinkPad 750C floppy controller and linux
>From: dan@symcom.math.uiuc.edu (Daniel R. Grayson)
>Date: 2 Apr 94 04:03:30 GMT
>Reply-To: dan@math.uiuc.edu
>Organization: University of Illinois at Urbana
>NNTP-Posting-Host: orion.math.uiuc.edu
>
>In case anyone wants to know, here is how we just managed to get linux
>working with the floppy controller on the IBM ThinkPad 750C.  The main
>difference is that when you read from port 3f7 and look at bit 7 to see
>whether the media has been changed, the controller reports 1 if not, and 0 if
>so (at least when the motor is on: when the motor is off, the status of the
>bit never changes).  This is exactly the reverse of the usual situation.
>
>To fix it, one must edit drivers/block/floppy.c so that the three occurences
>of
>
>	inb(FD_DIR) & 0x80
>
>are replaced by
>
>	!(inb(FD_DIR) & 0x80)
>
>We don't know what kind of controller chip it uses, because IBM says that
>information is PROPRIETARY!  But we managed to figure it out anyway with a
>great little msdos program called iospy which comes with the book "The
>Undocumented PC" by Frank van Gilluwe (publ Addison-Wesley, isbn
>0-201-62277-7).  Iospy will display the contents of ports on the screen in
>an out of the way place while you use debug to step through the BIOS or
>whatever.  Get it!
>
>
>..............................................................................
>If Murphy's Law were really true, every time you went to take a breath, all the
>air would be on the other side of the room.
>..............................................................................
>ecolson@husc.harvard.edu                   ecolson@ecolson.student.harvard.edu
>
>
>