Collection Item 

Casio ASA
Brand:  Casio. 
Model:  ASA. This example has a brand plate "Calcutronic" on the front and the back of the case. The ASA calculator is identical to the model 121A. 
Origin:  Japan. 
Introduction:  1971, my example has the Showa code 45.7.1 that means July 1, 1971. 
Type:  Basic desktop calculator with Nixie tubes display. Operates only with AC power (220v in my example). 
Functions:  4Basic function, no decimal point, no constant, no memory... just the basic! 
Display:  12 bright nixie tubes with no decimal point. No indication for negative, error, etc. As a guide you can use a sliding plastic rule to indicate the position of decimal point, thousands and millions, or any position you want. 
Keyboard:  15 reedswitch in two blocks: Numerals and Clear in white keys and the 4 basic functions in black keys. Note the rare notation =+ and = instead the classic += and = of the pseudoRPN calculators. 
Main chips:  Many chips from NEC and Hitachi, most with only 4 or 8 logic gates. This is the first generation of integrated chips. All components are mounted on two printed circuits boards connected by wires on one side. 
Logic comments:  Pseudo RPN notation, the classic approach of that time. Negative numbers are represented by the complementary system. 
Remarks:  Probably the first lowcost calculator from Casio. Also, the first model in the AS series. 
Size:  13.00 x 5.12 x 3.86 in, 330 x 130 x 98 mm. 
Condition:  (7/10) Very Good, not working. You can enter numbers but functions key does not generate any logic result, just erratic numbers. Probably there are one or more failed components. 