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: LightEmitting Diode Liion: Lithiumion rechargeable battery Lreg: Linear regression (2variable statistics) mA: Milliamperes of current Mtrx: Matrix support NiCd: NickelCadmium rechargeable battery NiMH: Nickelmetalhydrite rechargeable battery Prnt: Printer RTC: Realtime clock Sdev: Standard deviation (1variable 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 


Most of the calculators I own have nearly as many buttons as your average nuclear submarine. Not this one: the Casio SL800 is a basic fourfunction calculator. Its interesting claim of fame is that this is one of the few calculators that are truly credit card size.
It is easy to make a calculator that has the same width and height as a credit card. In fact, some of the cheapest promotional calculators that are given away as freebies are of this size. The Casio SL800, however, is creditcard size in all three dimensions: in other words, in addition to the width and height, it has the same thickness as those ubiquitous pieces of plastic.
I received this calculator from a former employer in Austria (thank you, Harald!) back in 1986. I've been carrying it in my wallet for the next 12 years or so, I sat on it many times, it's been left in the sun, in freezing cold, and more. Yet, despite the signs of heavy use, it still works and its display remains, if less than perfect, still entirely legible.
The calculator has no batteries, only a solar cell as its power source. In fact, the entire unit is a sealed plastic card, so it's actually the only waterproof, washable calculator in my possession.
Considering the engineering compromises that had to be made to pack the electronics of a calculator into a package that's only 1 mm thick, I am quite surprised, but very pleased, to see that it still works. I no longer carry this unit in my pocket; it is now part of my cherished collection.