Downloadable shareware: <http://www.simtel.net/pub/pd/44102.html>
 <ftp://garbo.uwasa.fi/pc/bootutil/>

 The included documentation says it works by writing a new boot sector on
 a disk in your a: drive that redirects the boot to your B: drive. (A
 similar utility is bboot.zip in the same directory at Garbo only.)

 If that doesn't work, you can always interchange your A: and B: drives
 by switching ribbon cables and changing the setup in your BIOS. From an
 article posted 27 Jan 1993 on another newsgroup:

 [begin quotation]
   Take  the  "ribbon" connector, as you call it, and  switch
   them.  To double-check, start at the end of the cable that
   connects to the motherboard or floppy controller.   Follow
   the  cable until you get to the first connector.   Connect
   this to the drive you want to be B:.
  
   After this, there should be a few lines on the cable  that
   get flipped left to right.  (On most cables, they just cut
   the lines and physically reverse them.  It should be quite
   obvious from looking at the cable.)  Anyway, the connector
   after  the pins get flipped right to left is the connector
   for your a: drive.
 [end quotation]