Casio fx-7700GBus

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: 1993  Display type: Graphical display  
New price:   Display color: Black  
    Display technology: Liquid crystal display 
Size: 6½"×3½"×½" Display size: 96×64 pixels
Weight: 6 oz    
    Entry method: Formula entry 
Batteries: 3×"CR-2032" Lithium + 1×"CR-2032" Lithium Advanced functions: Trig Exp Hyp Lreg Grph Intg Ab/c Cmem BaseN 
External power:   Memory functions:  
I/O: Serial port     
    Programming model: Formula programming 
Precision: 13 digits Program functions: Jump Cond Subr Lbl Ind  
Memories: 4(0) kilobytes Program display: Formula display  
Program memory: 4 kilobytes Program editing: Formula entry  
Chipset:   Forensic result: 9.000000590443  

These kind folks at Casio really know how to confuse the poor calculator enthusiast. Three nearly identical model numbers (fx-7700G, fx-7700GB, and fx-7700GBus); three different calculators! The GB/GBus models, as the name supposedly implies, are distinguished from the baseline version by the presence of a serial communications port.

The machine's programming model is demonstrated by this ultra-accurate implementation of the logarithm of the Gamma function, shown below:

Abs X->Z
(ln (2.506628275+6.34E-10+(225.5255846+1.92E-8)÷Z-
(Z-.5)ln (Z+4.65)-Z-4.65->G
X>0⇒Goto 1
ln(-π/Z/sin πZ)-G->G
Lbl 1