Radio Shack EC-4021
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 |
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Radio Shack EC-4021
Yet another pawn shop find: an old Radio Shack EC-4021 calculator, an OEM Sharp model. A very simple calculator this is; only 40 program steps, 3 memories, and no program control instructions of any kind. It is also one of those annoying models that zeroes the display when you switch to program entry mode, making it unnecessarily difficult to enter algorithms that yield an error on an argument of zero. Needless to say, you won't be able to implement a complex algorithm like that of the Gamma function on this beast. Here is instead a version of Stirling's formula, which calculates the extended factorial of the number on the display with quite good accuracy:
+ 1 = MS yx MR ÷ MR ex × ( 2 × π ÷ MR ) √ × ( 1 2 1/x ÷ MR ) ex =