In article ,
The Natural Philosopher wrote:

Well of course MAC OS/9 'select a boot device' took one look at the
Tiger disk and said 'dunno what that is' and refused to let me set it to
boot from back into OS/X.

Fortunately my PC was in the next room and a quick google and a print
gave me a series of random keys to press while doing yoga like exercises
to hit the reset button, and it finally 'came up OS-X'

One should be sufficient. Hold down option (aka alt) at boot time and
all the available bootable systems from all available devices (including
external drives) will be presented in a graphical interface (with
varying eye-candy depending on generation) for you to choose from.