Casio fx-50F/Radio Shack EC-4024 Program Collection: October 2026
Notes:
* The fx-50F/EC-4024 has a 29 step program space between two program spaces. Program steps can not be edited but can be cleared by [SHIFT] [ C ] (PCL) key sequence.
* Formula calls can not be included as a program step, but scientific constants can be. The values for the constants most likely are from the Japan Standards of 1978 (JISZ-8020-1978), so a little dated to 2026 standards.
* The Casio fx-10F is similar as fx-50F/EC-4024 except that the fx-10F does not have the scientific constants and has a slightly inclined keyboard.
* Mode changes can be included. SHIFT and Kin arithmetic calls are merged.
The programs presented today require inputs to be stored in registers 1-6 using [ SHIFT ] [ Kout ] (Kin) ((K)onstants In).
Angle Between 2 Lines (in Degrees)
Θ = arctan( abs((y – x) ÷ (1 + x * y)) )
abs(x) = √(x^2), key sequence: [ x² ] [ √ ]
x: slope of line 1 (Kin 1)
y: slope of line 2 (Kin 2)
Program Code (20 steps):
MODE 4 (degree)
(
(
Kout 2
-
Kout 1
)
÷
(
1
+
Kout 1
×
Kout 2
)
)
x²
√
TAN^-1
=
Maximum and Minimum of Two Numbers
The two numbers are stored in registers 1 and 2 (Kin 1, Kin 2).
max(x,y) = (x + y + abs(x – y)) ÷ 2 = min(x,y) + abs(x – y)
min(x,y) = (x + y - abs(x – y)) ÷ 2 = max(x,y) - abs(x – y)
Program Code (21 steps):
Kout 2
-
Kout 1
=
x²
√
Kin 3
(
Kout 1
+
Kout 2
+
Kout 3
)
÷
2
=
HLT (show maximum)
-
Kout 3
= (show minimum)
Terminal Velocity of a Spherical Object
vt = √(2 * g * mass ÷ (ρ * cd * exposed area of the object) (units: m/s)
≈ √(34.05656 * mass ÷ (π * radius^2))
The following constants are assumed:
g = 9.80665 m/s² (Earth’s gravitational constant)
ρ ≈ 1.225 kg/m³ (air pressure)
cd = 0.47 (coefficient drag of a sphere)
2 * g ÷ (ρ * cd) ≈ 34.06565 m^4/(s^2 kg)
Program Code (19 steps):
Kout 1
×
3
4
.
0
6
5
6
5
÷
(
π
×
Kout 2
x²
)
=
√
=
Ideal Thermal Voltage and Shockley Diode Equation
Thermal Voltage:
vt = k * T ÷ q * 10^3 (mV)
Shockley Diode Equation:
Id = Is * (exp(vD ÷ (n * vt)) – 1)
Ideal: n = 1
Inputs:
Is: scale current in milliamps (mA) Kin 1
Vd: diode voltage in millivolts (vA) Kin 2
T: temperature in degrees Kelvin (K) Kin 3
Outputs:
vt: Thermal Voltage (mA),
Id: diode current (mV)
Constant used (see comments on the scientific constants above):
k: Boltzmann Constant ([SHIFT] [ 8 ]): 1.380662 * 10^-23 J/K
(q) e: Electron Charge ([SHIFT] [ 4 ]): 1.6021892 * 10^-19 C
Program Code (21 steps):
Kout 3
×
k (SHIFT 8)
÷
e (SHIFT 4)
×
3
10^x
=
HLT (see vt: thermal voltage)
1/x
×
Kout 2
=
e^x
-
1
=
×
Kout 1
=
Source:
“Shockley Diode Equation” Wikipedia. Last Edited November 13, 2025.
https://en.wikipedia.org/wiki/Shockley_diode_equation
Retrieved June 19, 2026.
Eddie
All original content copyright, © 2011-2026. Edward Shore. Unauthorized use and/or unauthorized distribution for commercial purposes without express and written permission from the author is strictly prohibited. This blog entry may be distributed for noncommercial purposes, provided that full credit is given to the author.