HP 330 Service Information Manual page 161

The state diagram shown in Table 4-4 is executed in the interrupt service routine for the human
interface input device.
N ate that only keys [[] through [TI,
~
through
W ,
and [[] through
rn
are allowed to select
an OS. Other keys are simply ignored. This makes the handling of all nationalized keyboards
much simpler.
Because it is possible to find more OSses than there are lines on the display, the search scan can
be paused and continued by toggling the
I
Return
I
key. The line next to the bottom of the screen
indicates the current state with one of two messages:
SEARCHING FOR A SYSTEM (Press RETURN To Pause)
or
PAUSED (Press RETURN To Continue)"
The menu will wrap around to the top of the screen and overwrite itself whenever all available
lines are used. When the Boot ROM is paused, all activity stops. Because the keyboard is
polled, there may be a delay before a key press takes effect.
Boot ROM Functions
145