**Retro Review: Radio Shack EC-4024**

**Quick Facts:**

Model: EC-4024

Company: Radio Shack

Equivalent of: Casio fx-50F

Type: Scientific

Years: approximately 1987 - 1995

Display: 10 digits

Batteries: Solar

Logic: Algebraic (AOS)

Memory:

Registers: 7

Constants: 9

Pre-Programmed Formulas: 23

Programming Steps: 29 between 2 slots

**Features: A Little Bit of Almost Everything**

The EC-4024 has the following modes:

Mode 0: Compute (Main mode)

Mode 1: Base Mode (can be used in programs)

Mode 2: Linear Regression (y = A + Bx) (can be used in programs)

Mode 3: Single Deviation (one variable stats) (can be used in programs)

Mode 4: Degrees Angle Mode

Mode 5: Radians Angle Mode

Mode 6: Gradians Angle Mode

Modes 7, 8, and 9: Fixed, Scientific, and Normal (standard) display modes, respectively.

Mode . (decimal point) sets the EC-4024 in run mode while Mode EXP sets the EC-4024 in program writing mode.

The calculator handles fractions and converts results between fractions and decimal equivalents.

The base mode has the traditional four bases (binary, octal, decimal, hexadecimal integers) with Boolean algebra (OR, AND, NOT, XOR, NXOR, NEG).

**Equivalents**

The Radio Shack EC-4024 is the equivalent of the Casio fx-50F calculator from the late 1980s. There is a calculator similar to them both, which is a Casio fx-10F, however the fx-10F has an angled body and lacks the scientific constants.

**Constants**

Outside of the statistics mode, the shift keys of the 1 through 9 keys holds the following constants that can be recalled (1978 Japan Industrial Standard, JIS Z-8202-1978) :

1: C: Speed of Light: 299792458 m/s

2: h: Plank Constant: 6.626176 * 10^-34 J s

3: G: Universal Gravitational Constant: 6.672 * 10^-11 N m^2 kg^2

4: e: Elementary Charge: 1.6021892 * 10^-19 C

5: me: Electron Mass: 9.109534 * 10^-34 kg

6: u: Atomic Mass Unit: 1.66055655 * 10^-27 kg

7: Na: Avogadro Constant: 6.022045*10^23 / mol

8: k: Boltzmann Constant: 1.380662 * 10^-23 J/K

9: Vm: Molar Value of Ideal Gas at Standard Temperature and Pressure: 0.02241383 m^3/mol

What is neat about this is that the units are listed next the constant name. Example: C(ms^-1) is the shift function of the 1 key.

**Statistics Variables**

The following are the variables used in the statistics mode. The functions for the y values, A, B, and r are available to LR mode only. The left parenthesis key becomes the comma key, and the right parenthesis key is the predict key (LR mode only).

Shift 1: average of x values

Shift 2: population deviation of x values

Shift 3: sample deviation of x values

Shift 4: averages of y values

Shift 5: population deviation of y values

Shift 6: sample deviation of y values

Shift 7: A: intercept

Shift 8: B: slope

Shift 9: r: correlation

Kout 1: Σx^2

Kout 2: Σx

Kout 3: n (number of data points)

Kout 4: Σy^2

Kout 5: Σy

Kout 6: Σxy

**Formulas**

There are 23 formulas. The character that is on the far left side of the screen prompts for the variable to be entered. For a full list of formulas, please see the link below to download the manual. The fx-10F manual also applies to both fx-50F and EC-4024 as well.

Enter required values with the [RUN] key, not the [ = ] key.

**Programming**

The program capacity is only 29 steps. Thankfully, most of the shift/Kout/Mode key combinations are merged keystrokes. For example, [MODE] [ 5 ] takes only one step, and so does [SHIFT] [ 1/x ] (for x!). However, each press of a number key in terms of entering numbers takes a step, so to enter a numerical constant for example, 400, takes three steps ([ 4 ], [ 0 ], [ 0 ]). With only 29 steps, economy and storing constants prior to running programs is key.

There are a few programming tools:

x>0: Tests whether the value in the display is positive. If so, the program loops back to the first step in the program.

x≤M: Tests whether the value in the display is less than or equal to the value in the M register. If the test is true, the program loops back to the first step in the program.

ENT (the [RUN] key in write mode): Prompts the user to enter a value. You'll need to have a valid number entered to continue programming.

HLT (the [SHIFT] [RUN] key in write mode): Stops the calculator to show the display mid-program. Press the [RUN] key to continue.

ALPHA (the [FMLA] key in write mode): Prompts the user to enter a value with a prompt "A?" through "F?". The values are stored here are stored in registers 1 through 6, respectively.

A → K1, B → K2, C → K3, D → K4, E → K5, F → K6

Sample Program: Use the formula below to estimate gravity:

g = G * mass / radius^2 = G * A / B^2

G is the Gravitational Constant (use [SHIFT] [ 3 ])

Let A = mass

Let B = radius

Program: P1/P2 (you designate which program area to use)

SHIFT 3 (G)

×

FMLA a b/c (A?)

÷

FMLA ° ' '' (B?)

(enter a non-zero number here, like 1)

x^2

=

Test: Press P1/P2

Enter 5.96E24 at the A? prompt

Enter 6.38E6 at the B? prompt

Result: 9.76924362

All programming is done blind. The only edit function is that during programming, pressing [SHIFT] [ C ] erases the last step.

The program space can be erased by entering a number program from scratch or prior to choosing which program slot, pressing [SHIFT] [ C ]. A little confusing.

**Verdict**

The keyboard is very clean and organized. Despite the lack of steps, the EC-4024 is a great calculator and programmable scientific calculators that run on solar power are far and few between. I was lucky to find the EC-4024 because usually fx-10F, fx-50F, and EC-4024 are either not available or command a medium to high price.

Download the manual here:

Source:

Casio "fx-10F/fx-50F Scientific Calculator" manual.

Eddie

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