D
D
i
i
f
f
f
f
e
e
r
r
e
e
n
n
t
t
m
m
o
o
d
d
e
e
l
l
s
s
u
u
s
s
e
e
d
d
i
i
f
f
f
f
e
e
r
r
e
e
n
n
t
t
m
m
e
e
t
t
h
h
o
o
d
d
s
s
t
t
o
o
c
c
o
o
m
m
m
m
u
u
n
n
i
i
c
c
a
a
t
t
e
e
As has been discussed on page 7, the hp 39gs and
hp 40gs were aimed at different markets. Both of
them require communication with a PC and so both
come with a standard “mini-USB” port and cable.
The mini-USB cable (shown left) is identical to one
commonly used with digital cameras and
replacements can be bought very cheaply in any
electronics store.
Mini USB cable
Mini Serial cable
Although communication with a PC is identical on both models, the similarity ends there. On the hp 39gs
communication between calculators is accomplished using the infra-red port. This is very similar in operation
to that of a remote control. Communication is only possible over a very short distance – up to about 8cm.
In the markets for which the hp 40gs was designed infra-red communication was not considered desirable
and a mini-serial cable connection is used instead. This cable (shown above right) connects two hp 40gs
calculators via their mini-serial ports. It is an HP proprietary cable which can only be purchased from HP or
an HP reseller. Both cables are supplied with the hp 40gs calculator as standard equipment but the hp 39gs
is supplied standard with only the mini-USB cable because there is normally no need for the mini-serial cable
with an hp 39gs. The mini-serial port is still present though because it is anticipated that it may be used in the
future to connect to data-loggers and other possible peripherals.
Mini-USB port
Mini-serial
port
Infra-red port
If you are using the cable on an hp 40gs then alignment of the calculators
is obviously not a problem. For infra-red, of course, it is. Look at the
keyboard side of the calculator, near the HP label above the screen, you’ll
find a small black triangle. This marks the position of the infra-red port so
that you can line up calculators when looking down from above.
227
