Casio FX-29

The Casio FX-29 is a scientific calculator from 1977. It has a sleek plastic case with brushed aluminum panels and measures 84mm x 152mm x 22.5mm. Weighing 148g without batteries, the FX-29 runs on two AA batteries or an AC adapter.

The calculator features a blue vacuum fluorescent display (VFD) with eight main digits and a ninth digit for negative numbers. Inputs are made through a subtle black and gray keyboard with orange highlights on the power and units keys.

In terms of functionality, the FX-29 handles basic arithmetic, square roots, trigonometry, logs, and statistics. It can display fractions, degrees/minutes/seconds, and scientific notation. The calculator has a four-function memory and overflow suppression on input.

Inside, the FX-29 contains a Hitachi HD36130 central processing unit along with transistors, diodes, capacitors, resistors, and a transformer. The keyboard connects to the main circuit board via copper wires. Opening the case involves removing one screw and carefully popping the rigid plastic lugs on each side.

Some key details about the logic and interface:

  • The C key clears the input, AC clears everything
  • Overflow is suppressed, 9th digit ignored
  • Constant function via double press of operator
  • No indication of memory usage
  • Negative sign pushes left, allows 8 digit negatives
  • Overflow shows E, not recoverable
  • Divide by 0 shows E, not recoverable
  • Negative roots error as E
  • Scientific mode limited to 6 digit input
  • Change sign mid-number entry allowed
  • No error recovery

The Casio FX-29 represented an early milestone in handheld scientific calculators. With its efficient design and useful features, it remained popular well into the LCD era. The FX-29 demonstrated Casio’s strengths in packaging, interface, and miniaturized electronics.

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