Casio fx-5500

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: 1986  Display type: Alphanumeric display  
New price:   Display color: Black  
    Display technology: Liquid crystal display 
Size: 3"×5"×½" Display size: 12 characters
Weight: 4 oz    
    Entry method: Algebraic with precedence 
Batteries: 2×"CR-2032" Lithium Advanced functions: Trig Exp Hyp Lreg Symb Cmem Const 
External power:   Memory functions: +/- 
    Programming model: Formula programming 
Precision: 11 digits Program functions:  
Memories: 12 numbers Program display: Formula display  
Program memory: 237 program steps Program editing: Formula entry  
Chipset:   Forensic result:  

fx5500.jpg (25906 bytes)This beautiful little calculator is a surprising machine. Like many other Casio calculators, it has a formula memory, which qualifies it as a simple programmable device (albeit without conditional execution or branching capabilities.) However, in addition to storing and executing formulae, this machine can do something few other calculators can: it can symbolically manipulate formulae. It can expand, factor, and simplify formulae, and also solve linear or quadratic equations. Not bad!

The limitation of each formula to 79 steps is, however, quite a drawback. Because of this, I see no way to implement my favorite, the Gamma function. Stirling's formula, on the other hand, fits easily:


The method used here makes the formula operate on the result of any previous calculation, rather than prompting for the values of any independent variables.