5
K
K
E
E
Y
Y
S
S
&
&
N
N
O
O
T
T
A
A
T
T
I
I
O
O
N
N
C
C
O
O
N
N
V
V
E
E
N
N
T
T
I
I
O
O
N
N
S
S
There are a number of types of keys/buttons that are used on the hp 39gs and hp 40gs.
The basic keys are those that you see on any calculator including scientific ones, such as the numeric
operators and the trig keys. Most of these keys have two or more functions, with the second function accessed
via the
SHIFT
key and the alphabetic character accessed via the
ALPHA
key.
Take for example the
COS
key shown left. If you just press the key,
you get the
COS
function. However above left of the key and below
right you will see two additional meanings assigned via the
SHIFT
and
ALPHA
keys.
In this book, all references to buttons, whether they need the
SHIFT
key or not, are written in this typeface:
KEY
.
The SHIFT and ALPHA keys
The
SHIFT
key gives you the second function for each key. In the case of the
COS
key, the second function is
ACOS
, sometimes referred to as arc-cos or cos
-1
or inverse cos. Most keys have these second functions that are obtained via the
SHIFT
key.
Note: When I want you to use one of these keys that needs to have the
SHIFT
key pressed first I usually won’t say so. It seems to me that you’re intelligent
enough to work out for yourself when the
SHIFT
key needs to be pressed.
The ALPHA key
The next modifier key is the
ALPHA
key. This is used to type alphabetic
characters, and these appear below and right of most keys. Pressing
SHIFT
before the
ALPHA
key will give lower case alphabetic characters. In many views
the calculator can be locked in
ALPHA
mode using one of the screen keys. You
can also simply hold down the
ALPHA
key.
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