Radio Shack EC-4020

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:   Display type: Alphanumeric display  
New price:   Display color: Black  
    Display technology: Liquid crystal display 
Size: 5"×3"×½" Display size: 12 characters
Weight: 4 oz    
    Entry method: Formula entry 
Batteries: 2×"CR-2032" Lithium Advanced functions: Trig Exp Hyp Lreg Cmem BaseN 
External power:   Memory functions: +/-/×/÷ 
    Programming model: Keystroke entry 
Precision: 12 digits Program functions: Jump Cond Subr Lbl Ind  
Memories: 94(26) numbers Program display: Mnemonic display  
Program memory: 550 program steps Program editing: Auto-insert program entry  
Chipset: Casio fx-4000P   Forensic result: 9.00000716758  

ec4020.jpg (25744 bytes)Over the years, Radio Shack released many OEM calculators under the Radio Shack or Tandy brand names. The EC-4020 is their OEM version of the Casio fx-4000P. It is certainly programmed the same way as other high-end Casio calculators, as demonstrated by the Gamma function implementation shown here.

? -> X:
1 -> Y:
Lbl 1:
X >= 0 => Goto 2:
X×Y -> Y:
X+1 -> X:
Goto 1:
Lbl 2:
e(ln ((1+(76.18009172+9.5E-9)/(X+1)-86.50532033/(X+2)+
√(π×2)/X)+(X+.5)× ln (X+5.5)-X-5.5)/Y