Hewlett-Packard HP-22S
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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Hewlett-Packard HP-22S
The HP-22S belongs to the Pioneer series of Hewlett-Packard's line of calculators. Although it is a close relative to the HP-20S and HP-21S, it is not a keystroke-programmable machine; instead, it has a built-in "SOLVE" function that lets you enter equations in algebraic form and solve for unknown variables. Since this SOLVE feature also has the capability to evaluate formulae, this makes the HP-22S technically a programmable machine; you can enter a mathematical expression which is then stored permanently in the calculator's continuous memory, and you can evalute the expression at a later time.
Whereas some other Hewlett-Packard calculators with a similar SOLVE feature offer special functions for conditional execution or loops, these functions are not present in the HP-22S. Therefore, this calculator is limited to more straightforward formulae. That said, I was suprised to find that the machine has sufficient storage for an implementation of my favorite example, the Gamma function, with plenty of memory to spare.
G=SQRT(2×π)÷X×(1.00000000019+ 76.1800917295÷(X+1)-86.5053203294÷(X+2)+ 24.0140982408÷(X+3)-1.23173957245÷(X+4)+ 1.20865097387E-3÷(X+5)-5.39523938495E-6÷(X+6))× (X+5.5)^(X+.5)÷EXP(X+5.5)
Looks ugly, but it works! Better yet, thanks to the built-in SOLVE feature, we automatically get an inverse Gamma function as well. Instead of specifying X and solving for G, you can specify G and solve for X; for instance, you can determine that the Gamma function's value is exactly 100 for 5.89251869634.