41CL User Manual
© 2019, Systemyde International Corporation
7
Can my calculator be upgraded?
The 41CL is an upgrade created by replacing the CPU circuit board in a 41C/CV/CX with
the 41CL circuit board. This replacement is only possible for calculators that actually
have a CPU circuit board. The easiest way to tell if this is the case is to look at the HP-41
display. If the light part of the display has square corners, like those shown below, the
calculator is a candidate for replacing the CPU circuit board.
Hewlett-Packard changed the display driver circuitry in the 41 series during production,
and this change affected one component value on the CPU circuit board. The 41CL
circuit board implements the component value used in later production units. Units with
the correct display driver can be identified as follows:
•
I
f
your
41C
(
not
CV
or
CX)
ha
s
a
s
e
r
i
a
l
numbe
r
s
t
a
r
t
i
ng
wi
t
h
“
1954”
or
l
a
r
ge
r
i
t
us
e
s
the correct display driver.
•
I
f
your
41CV/
CX
ha
s
a
s
e
r
i
a
l
numbe
r
s
t
a
r
t
i
ng
wi
t
h
“
2003”
or
l
a
r
ge
r
i
t
us
e
s
t
he
c
or
r
e
c
t
display driver.
It is theoretically possible to use the 41CL circuit board with the older display driver, but