DISK SWITCHING
by Beverly Howard, Kaypro Club Austin, August 1987

(What happens when you don't reset log in a new disk)

Important Reminder:  Remember that in CP/M, the computer needs to
be told each and every time a different floppy is inserted in a
disk drive.  If you are at the "A>" prompt, you notify the system
of the change by typing CTRL-C  after you insert a disk.  This
important action avoids both the BDOS error nuisance and the more
serious possibility of major damage to your disk's directory and
files.  Many programs such as Wordstar and Newsweep that allow
disk swapping have "Log Disk" features which send the "CTRL-C"
signal to the computer, and it is equally important to use this
function after swapping or inserting disks.  Another
misconception is that typing "DIR" will notify the computer that
a new disk has been inserted.  That is not the case.

The most common problem resulting from not typing a CTRL-C or
correctly logging in the disk is the message "BDOS error - Drive
B: R/O" when you or the program attempts to write a file to the
new disk.  In the middle of a program such as Wordstar or dBase,
you may find to your dismay that the computer dumped you back to
the "A>" prompt, and all the work you accomplished since your
last save has been lost.  The dBase command to log a new disk is
"RESET" after the switch, but be warned that unless all of the 
.DBF files you have been using on that disk have been closed
("USE" by itself), the files may have been permanently damaged
when the current disk was removed.