From: ohland@charter.net   
      
   Oops, good thing I searched the definition... I DIMMly remembered a book   
   title from the early 70s...   
      
   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. 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.   
      
   Question - 1GB -or- 1,023KB? I remember trying a Fujitsu full height F/W   
   SCSI drive with 1,024KB (From Hi Tech Cafe). My 8595-0KF and a high   
   priced Corvette were not having it. Peter sendt me a pair of enhanced T1   
   complex BIOS chips (one to use, one to lose), and it fired up.   
      
   Ah, the Corvette of a high price. Turns out that Caroll Bloyd and I were   
   fighting over it. I beat him with $150, IIRC.   
      
      
   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.   
      
   Question - does Int 4Bh func. 80h - "IBM SCSI interface" actually have   
   any documentation, or is this moniker a SWAG?   
      
   Question - The non-enhanced use the Int13 Funct 1Fh to manipulate the   
   IML fencing. "All T1 system ROMs contain IBM SCSI extensions" that   
   "provides extended SCSI services, incl. SCB". So SCB is there, but not   
   used, or does the early BIOS SCB support lack the SOS Max_LBA that the   
   enhanced BIOS uses to fence the IML partiton?   
      
   The IML routine code allocates EBDA block for SCSI variables, and if not   
   already present in memory, it installs the embedded SCSI ROM extensions.   
      
   Question - "embedded SCSI ROM extensions" from what? The complex BIOS?   
   The IBM SCSI controller?   
      
   Question - for systems with on-board SCSI, like the Bermuda, can we stop   
   the IML process from loading the whatever for the SPOCK and then load a   
   Corvette's code or whatever, instead? Something akin to that would be a   
   P75, with a Corvette as the sole SCSI controller... Sure, the P75 is not   
   IML, but the system loads the 8032 based SCSI first, and won't let a   
   Corvette lay rubber...   
      
   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.   
      
   NOTE: The "non-enhanced" T2 ROM lacks the ESDI code.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)