I recently purchased two calculators from https://www.devicegoround.com:
* Casio fx-115D SUPER-FX and
* Radio Shack EC-4004 (I'll talk about this in another post).
Date the fx-115D SUPER FX was first manufactured: about 1995, according to calculator.org (http://www.calculator.org/pages/calculator.aspx?model=fx-115D&make=Casio
I honestly thought this model was around in the late 1980s or early 1990s. Hard to tell when Casio does not date their user manuals.
As with most solar-powered calculators, the fx-115D SUPER FX (herein referred to as fx-115D from this point forward) has a battery backup. This means we can store data and it will be retained after the calculator is turned off.
In addition to the independent memory (M), the fx-115D has six additional memory registers. The Kin key stores the number into one of the six registers, which the Kout key is the recall key. Better yet, the fx-115D supports storage arithmetic.
Storage Arithmetic:
Let # represents registers 1 through 6:
Add x to #: x [ Kin ] [ + ] #
Subtract x from #: x [ Kin ] [ - ] #
Multiply x to #: x [ Kin ] [ × ] #
Divide #/x: x [ Kin ] [ ÷ ] #
Constant arithmetic operation keys are executed by pressing the arithmetic key twice. Then enter each operand then the equals key. I wonder if anyone used this feature? Here are the procedures for constant arithmetic operation:
Addititon: x + a, x + b, etc...
x [ + ] [ + ] a [ = ], b [ = ], repeat
Subtraction: a - x, b - x, etc...
x [ - ] [ - ] a [ = ], b [ = ], repeat
Multiplication: x * a, x * b, etc...
x [ × ] [ × ] a [ = ], b [ = ], repeat
Division: a/x, b/x, etc...
x [ ÷ ] [ ÷ ] a [ = ], b [ = ], repeat
Other features include:
* Complex Numbers. This is unique for the time as complex numbers were the imaginary parts were entered with a [ i ] key (actually Kin and Kout were deactivated in this mode) instead of the a and b keys. Available functions in complex numbers: arithmetic, 1/x, absolute value, and argument. Powers, logarithms, and trigonometric functions worked only on real numbers.
* Engineering Mode. The shift of the number keys allowed the user to enter an engineering prefix (nano-, micro-, etc...).
* Single Variable statistics
* Linear Regression
* Base Mode with conversion, with Boolean functions AND, NOT, OR, XOR, and XNOR. The [ 1/x ] acts like a negation key, but I am not sure it is 1's or 2's compliment. The manual doesn't state.
* Fractions, complete with mixed/proper fraction conversion. The decimal/fraction works to, if you initially enter a fraction.
* ENG and <-ENG key. These represent a number in different ways:
ENG: decreases the exponent part by 10^3, multiplies the mantissa by 1000
<-ENG: increases the exponent part by 10^3, divides the mantissa by 1000
Example: 23400 [ = ]
[ ENG ] (23.4 x 10^3)
[ ENG ] (23400 x 10^0)
[ ENG ] (23400000 x 10^-3)
23400 [ = ]
[ <-ENG ] (0.0234 x 10^6)
[ <-ENG ] (0.0000234 x 10^9)
[ <-ENG ] (0.0000000234 x 10^12)
These keys are still present on Casio non-graphing calculators, including the entry level fx-260 Solar.
The operating system is AOS (Algebraic Operating System). I realize that AOS is a Texas Instruments term, but it applies here. Simply put, any one-argument function (e^x, trig, log) are pressed after the number is entered. Example:
ln 2431.74 is calculated as 2431.74 [ ln ] (Result: 7.796362329)
Another calculator that I had fond memories of is now back in the collection.
Eddie
This blog is property of Edward Shore. 2014
