Hewlett-Packard HP-19BII

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: 1990-2001 Display type: Graphical display  
New price:   Display color: Black  
    Display technology: Liquid crystal display 
Size: 6"×8"×½" Display size: 137×32 pixels
Weight: 8 oz    
    Entry method: Algebraic with precedence 
Batteries: 3×"N" alkaline Advanced functions: Trig Exp Lreg Solv Fin Cmem Snd Mtrx 
External power:   Memory functions: +/-/×/÷ 
I/O: IR output     
    Programming model: Formula programming 
Precision: 12 digits Program functions: Jump Cond  
Memories: 6700(0) bytes Program display: Formula display  
Program memory: 6700 bytes Program editing: Formula entry  
Chipset: Saturn   Forensic result:  

Hewlett-Packard HP-19BII

hp19b2.jpg (53732 bytes)The clamshell design of the HP-19B calculator must obviously have been popular: that machine's direct successor, the HP-19BII, was still sold by Hewlett-Packard more than ten years after its introduction.

Like its predecessor, the HP-19BII also has the "SOLVE" feature as a form of programmability, and includes the conditional function IF and the summation function Σ.

The example I developed for this calculator is an implementation of the Gamma function, extended over the domain of negative numbers with the use of the conditional and summation functions.

G=(-1)^Σ(I:X:0:1:1)÷EXP(Σ(I:X:15:1:LN(ABS(i))))×
L(Q,Σ(I:X:15:1:1)+X)^Q÷EXP(Q)×SQRT(2×PI÷Q)×
EXP(((((1÷1188÷SQ(Q)-1÷1680)÷SQ(Q)+1÷1260)÷SQ(Q)-1÷360)÷SQ(Q)+1÷12)÷Q)