Date   : Fri, 12 Nov 1982 1709-:00EST
From   : Bob Clements <CLEMENTS@Bbna>
Subject: when to log-in a new disk?

In response to your message of 12 Nov 1982 1628-EST

Either I misunderstand your question, or the answer is much simpler
than Steve's suggestion.

Whenever the BDOS calls the SELDSK entry of BIOS, it supplies
its idea of whether the drive is new. Bit 0 of register E is a 1
if the drive is already logged, and a 0 if it's new, as determined
by the "logged disks" vector. So your BIOS should check that bit
and do any needed setup only when the bit is zero.
So if you go through the warm boot routine (by typing ^C)
when you change media, you're all set. If you're trying
to detect changed disks WITHOUT a warm boot, I can't help you.

/Rcc