Casio fx-4000P

Datasheet legend
Ab/c: Fractions calculation
AC: Alternating current
BaseN: Number base calculations
Card: Magnetic card storage
Cmem: Continuous memory
Cond: Conditional execution
Const: Scientific constants
Cplx: Complex number arithmetic
DC: Direct current
Eqlib: Equation library
Exp: Exponential/logarithmic functions
Fin: Financial functions
Grph: Graphing capability
Hyp: Hyperbolic functions
Ind: Indirect addressing
Intg: Numerical integration
Jump: Unconditional jump (GOTO)
Lbl: Program labels
LCD: Liquid Crystal Display
LED: Light-Emitting Diode
Li-ion: Lithium-ion rechargeable battery
Lreg: Linear regression (2-variable statistics)
mA: Milliamperes of current
Mtrx: Matrix support
NiCd: Nickel-Cadmium rechargeable battery
NiMH: Nickel-metal-hydrite rechargeable battery
Prnt: Printer
RTC: Real-time clock
Sdev: Standard deviation (1-variable statistics)
Solv: Equation solver
Subr: Subroutine call capability
Symb: Symbolic computing
Tape: Magnetic tape storage
Trig: Trigonometric functions
Units: Unit conversions
VAC: Volts AC
VDC: Volts DC
Years of production: 1985  Display type: Alphanumeric display  
New price:   Display color: Black  
    Display technology: Liquid crystal display 
Size: 5½"×3"×½" Display size: 12 characters and 3 digits
Weight: 5 oz    
    Entry method: Formula entry 
Batteries: 2×"CR-2032" Lithium Advanced functions: Trig Exp Hyp Lreg Cmem BaseN 
External power:   Memory functions:  
    Programming model: Formula programming 
Precision: 12 digits Program functions: Jump Cond Subr Lbl Ind  
Memories: 94(26) numbers Program display: Formula display  
Program memory: 550 program steps Program editing: Formula entry  
Chipset:   Forensic result: 9.00000716758  

fx4000p.jpg (23375 bytes)After initially offering such marvellous calculators as the fx-201P or the FX-602P, Casio went steadily downhill; most of their later programmable models have extremely limited programmability, both in terms of capacity and in terms of functionality.

Not so the fx-4000P. This is a no-compromise, high-end, classic programmable. With a full set of scientific functions and a whopping 550-step program memory, this is definitely a serious engineering tool. They just don't make machines like this anymore!

I first came across the fx-4000P in its OEM guise as the Radio Shack EC-4020. At the time, I did not yet know about the fx-4000P model number, so the find represented a bit of a mystery.

In 2012, some 13 years after I received my first EC-4020 and 11 years after I came across the first fx-4000P, a kind calculator owner, Aron from NJ sent me his old fx-4000P, this time with an English manual. At last! (Well, I did have a German manual and the English manual for the EC-4020, but it's not quite like the real thing.) I must say, it is still a lovely, very capable machine; my only two complaints are the somewhat hard to read display and a less than ideally robust construction.

The program below, intended to demonstrate the fx-4000P's programming model, uses the Lanczos-approximation to accurately compute the logarithm of the Gamma function. A conditional expression is used to compute the correct result for negative arguments (the machine must be in radians mode; also note the difference between minus signs, '-', and subtraction signs, '−'):

Abs X→Z:
ln (2.506628275+6.3E-10+(225.5255846+1.9E-8)÷Z−
(Z−.5)ln (Z+4.65)−Z−4.65→G:
X<0⇒ln (-π÷X÷sin πX)−G→G:G