Collection Item 

Casio FX90B
Brand:  Casio. 
Model:  FX90B. 
Origin:  Japan. 
Introduction:  1980? 
Type:  Pocketsize scientific calculator with LCD display and solar cell operation. 
Functions:  4 basic functions, constant, memory, scientific notation, 6level parenthesis, powers, roots, reciprocal, factorial, random number generator, Pi constant, fractions and percentages. Trigonometric direct/inverse functions with angle in degrees, radians and gradients, Hyperbolic direct/inverse functions, Natural/Base10 logarithms, exponentials (10^x and e^x), Coordinates systems conversion (Rectangular to Polar and viceversa). Statistical functions: Number of data, Sum of value and square value, Arithmetic Mean and Standard Desviation. Results can be displayed in fixed or scientific notation. Also you can see fractional numbers (for example 12 7/8) and sexagesimal notation for degrees, minutes and seconds (for example 12ยบ 21' 30"). No programming capability. 
Display:  LCD display with white background and black characters. Scientific notation with 10+2 digits (mantissa and exponent) with negative sign in both components. Nine additional indicators for: Shift key, Memory content, Konstant, Angle mode (DEG, RAD, GRA), Notation mode (Fixed,Scientific) and Statistical mode. 
Keyboard:  24 standard rubber keys on the body of the calculator for basic functions plus 28 ultrathin membrane keys for additional functions. No On/Off key. 
Main chips:  Unknown, I have to destroy this calculator to see the chip inside! 
Remarks:  Very elegant and ultra compact scientific calculator. Must be handled with care! 
Size:  Unfolded: 8.15 x 2.64 x 0.28 in, 207 x 67 x 7 mm. Folded: 4.10 x 2.64 x 0.43 in, 104 x 67 x 11 mm. 
Condition:  (10/10) New, unused, minimal marks on cardboard box, full working. All keys are operative. 
Accesories:  Original cardboard box and operation manual in english/spanish. 
Download:  Casio FX90B Operation/User manual in english and spanish in PDF format, click here. Advertisement on Popular Science magazine, september 1984, click here. 
See also:  Casio FX190 and FX191. 
Pictures taken with 