Texas Instruments TI-67 Galaxy

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:   Display type: Alphanumeric display  
New price:   Display color: Black  
    Display technology: Liquid crystal display 
Size: 3½"×5"×½" Display size: 12 characters
Weight: 5 oz    
    Entry method: Formula entry 
Batteries: 2×"LR44" button cell Advanced functions: Trig Exp Hyp Lreg Solv Intg Ab/c Cplx Cmem Const 
External power:   Memory functions: +/-/×/÷ 
    Programming model: Formula programming 
Precision: 13 digits Program functions: Jump Cond Subr Lbl  
Memories: 1536(0) bytes Program display: Formula display  
Program memory: 1536 bytes Program editing: Formula entry  
Chipset:   Forensic result:  

ti67.jpg (27206 bytes)For all practical intents and purposes, the TI-67 looks like a much needed upgrade of the popular TI-68 calculator. Not only does the TI-67 have more than three times the memory of its "bigger" cousin, it also offers capabilities that turn the machine into a true programmable: the ability to call subprograms, evaluate expressions conditionally, and execute loops.

Appearance-wise, the TI-67 belongs to the "Galaxy" series of calculators that includes the TI-65 and the TI-66. The TI-67 does, however, have a more robust appearance; it also sports a hard cover that prevents premature battery drain or other malfunctions due to erratic keystrokes that can occur during storage.

The programming model of the TI-67 is essentially a formula programming model, but it does offer advanced features that go beyond evaluating simple expressions. A formula can contain multiple expressions separated by the colon character. Additionally, formula storage is also used to store "programs", that are really formulae that do not readily evaluate to a value; they may contain instead instructions such as goto or lbl that permit complex flow control.

This is best demonstrated by my favorite programming example, the Gamma function. The implementation shown here computes this function's logarithm using the modified Stirling formulae, made accurate for small values with an added iteration. In addition to positive arguments, the formula also evalutes for negative values whose integer part is odd (e.g., -3.5). The program does not prompt for input; it uses instead the result of the last computation (Ans) as its input argument. The program's result is both displayed and stored in Ans for further chain calculations.

lbl L:
if X>9:
goto G:
goto L:
lbl G:
X*ln X-X-ln LNG+ln √(2*π÷X)+((((1÷1188÷X2-1÷1680)÷X2+1÷1260)÷X2-1÷360)÷X2+1÷12)÷X

Note that this program has been broken up into multiple lines for readability; on the calculator, it appears as a single formula line.