HP 9100B Operating & Programming Manual page 26

NOW YOUR 91008
AL
I
lf a mathematically illegal operation, such as division by 0, is
performed, then a light, located at the left of the display, is
'set' (lights up). lf the calculator 1s running a program when
the illegal operation occurs the light will remain lit, but the pro-
gram will continue to run. The light can be 'reset' (switched
off) by pressing any key on the keyboard. Illegal operations are
listed on Page
21.
EXAMPLE:
division by 0 (zero)
SWITCH:
RUN
PRESS: CLEAR
the light 'sets'.
1
t
0
•
-
•
Notice that the operation is performed even though
lf
is 'Illegal'; the result, 9.999 999 999 x
10
99
,
which
is infinity as far as the calculator is concerned, ap-
pears in the Y register.
PRESS: any key
the light 'resets'.
NOTE
There are (apparent) exceptions to this when a key
is pressed which then performs another illegal opera-
tion; although the light does 1n fact 'reset' it will be
immediately 'set' by the new 1llegal operat1 on.