From: ohland@charter.net   
      
   The original IML implementation relies largely on standard BIOS calls   
   but uses a few undocumented functions - namely, the Int 13h func. 1Fh   
   calls used to manipulate the IML fencing.   
      
      
   1) The original implementation can only load an IML image from a floppy   
   drive or the first hard drive (limited to 1GB). The T0, early T1, and   
   early T2 complex ROMs use this method.   
      
      
   All T1 system ROMs contain IBM SCSI extensions consisting of the   
   "standard" Int 13 routines and a proprietary Int 4Bh func. 80h - "IBM   
   SCSI interface." This iface provides extended SCSI services, incl. SCB   
   (Subsystem Control Block) support.   
      
      
   The IML routine code allocates EBDA block for SCSI variables, and if not   
   already present in memory, it installs the embedded SCSI ROM extensions.   
      
   If ESDI or SCSI was successfully initialized, the POST uses the standard   
   Int 13h iface to read the first three sectors of the system partition   
   from the first hard drive. If a compatible IML record is found, POST   
   Stage 1 ends by calling it.   
      
   If the hard drive IML load fails, the system re-checks the floppy drive   
   for an IML record. If not found, the system prints an IML error and   
   finally halts.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)