TD> With Dual-boot, both OSs (must) reside on the same partition (C:). You
 TD> use BOOT/DOS and BOOT/OS2 to switch between them. The BOOT program
 TD> rewrites the boot sector and copies the appropriate config files into
 TD> the root directory before rebooting. Also obviously (or maybe not)
 TD> the drive has to be FAT.
And also BIOS virus detection has to be disabled, as has any resident 
anti-virus software, otherwise it will complain when BOOT (quite properly) 
attempts to write the correct boot sector for the selected operating system.
 TD> With boot manager, each OS is on its own partition, which normally
 TD> becomes C: once selected. Whichever is selected, the other is
 TD> invisible (I think).
Boot manager simply has an internal table of partitions and names.  The 
"visibility" of the partition is controlled by the standard disc partitioning 
rules, which are independent of Boot Manager.  
One such rule is that of the four primary partitions available in the primary 
Master Boot Record, only one, the "active" one, should be visible.  So if you 
have DOS and OS/2 Warp installed in separate primary partitions, then yes, 
booting the one will make the other invisible and inaccessible.  However, it 
is recommended that if one is starting from a blank hard disc, one install 
OS/2 in a logical drive in an extended partition, and not in a primary 
partition.  OS/2, unlike DOS and DOS+Windows 95, will quite happily boot from 
a non-primary partition.  Using this configuration means that there won't be 
multiple primary partitions rendering each other invisible, but just the one 
primary partition, containing DOS, which will always be visible.
 ¯ JdeBP ®
--- FleetStreet 1.19 NR
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