Litronix 2290

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: Numeric display  
New price:   Display color: Red  
    Display technology: Light-emitting diode 
Size: 5½"×3"×1" Display size: 8 digits
Weight: 7 oz    
    Entry method:  
Batteries: 3×"AA" alkaline Advanced functions:  
External power: Litronix adapter   Memory functions:  
    Programming model: Keystroke entry 
Precision: 8 digits Program functions:  
Memories: 1 numbers Program display:  
Program memory: 10 program steps Program editing:  
Chipset:   Forensic result:  

*Four-function programmable!

l2290.jpg (24379 bytes)If there had been an award given for the least functional programmable calculator ever made, the Litronix 2290 would have been a strong contender. Imagine: a basic, four-function calculator with square root (hit ÷ +=) and percent, a single memory register, and room for 10 program steps! It makes me wonder why its designers bothered with programmability at all.

The 2290's programming model is somewhat unusual. Like many of the earliest programmables (e.g., the Novus 4525 from National Instruments) it provides no capability for viewing or editing programs. It simply memorizes your keystrokes, that's all. However, unlike other programmables, the 2290 only memorizes operator keys; when numeric keys are used, for instance, they are interpreted as a halt instruction, causing the calculator to wait for user input.

This is demonstrated by the example shown on the calculator's back label. You can key in a program sequence to multiply two numbers as follows:

C/ON L 2 × 3 += S

To play back the program, you'd then type

10 E 5 E

and the calculator displays 50, the product of 10 and 5. (Incidentally, this also means that it is impossible to store a constant value in a program.)

With 10 programming steps and 4 functions, it is rather difficult to conceive a program that's even remotely meaningful. Certainly no way to implement the Gamma function, the factorial, or even Stirling's formula on this beast! Instead, here's a simple exercise from Newtonian physics, calculating the amount of time it takes for an object to fall from a given height. Storing the gravitational acceleration (9.81 m/s² at sea level) in the calculator's memory, you can key in the following program:

C/ON L += += ÷ RM ÷ += S

To calculate, for instance, the number of seconds it takes to fall from a height of 100 meters, type 100 E (the result is 4.67 seconds. Not a heck of a lot to say your prayers if you happen to jump out a window on the 30th floor.)