BB> OS/2 will interrogate the actual hardware via the IBM1S506.ADD driver
 BB> and if you add a /V parameter it will show bios geometry, actual
 BB> geometry, and geometry being used. 
I haven't traced completely through the source yet, but as far as I can see
from what I have looked at so far the values in Act ("actual") are what are
reported to the higher layers of OS/2, the values in I13 ("INT 13h") are what
were found by the OS/2 boot loader when it interrogated INT 13h (which it 
oes
before loading the kernel, so that information as to what disc drives the 
IOS
thinks are present is available to device drivers, so that they in turn can
align their configurations with that of the BIOS), the values in CMD 
("command")
are any geometry overrides specified on the command line, and the values in 
D
("Identify") are the values returned from the ATA IDENTIFY command to the 
isc
controller chips themselves.
Just in case you, or anyone, were interested.
 ¯ JdeBP ®
--- FleetStreet 1.19 NR
---------------