Casio H-1

Casio H-1 Calculator

The Casio H-1 is a slim, handheld calculator released in 1982-1983. It measures 77mm x 136mm x 19.7mm and weighs 108g without batteries. The H-1 is powered by two AA batteries or an optional AC adapter. With manganese batteries it lasts about 8 hours, while alkaline batteries extend use to 28 hours.

Casio H-1 Calculator

The case design is typical of early Casio calculators. It has a cream plastic base and brown smooth plastic top, with brushed aluminum panels surrounding the display and keys. The model name and logo are printed on top. There is a switch to control decimal rounding. The blue vacuum fluorescent display (VFD) shows 8 digits.

The H-1 performs basic 4 function calculations, percentages, square roots, and has a two value memory. The vintage technology source states this model lacks a 9th digit, limiting the calculator in some cases. Negative numbers are also limited to 7 digits.

Casio H-1 Calculator

Inside, the main components are:

  • CPU: NEC D1877C 8303K9 – 28 pin DIL chip
  • Display: NEC LD8225 single glass tube 8 digit VFD
  • 1 transistor, 7 diodes, 7 capacitors, 4 resistors
  • Transformer

The main and keyboard circuit boards connect via 16 copper wires. Opening the case requires removing 1 screw on the back and gently prying from the bottom.

Casio H-1 Calculator

There is an H-1 version and an H-1 B version. the B version is a later revision of the earlier H-1. The H-1 uses the same IC and components except for 8 diodes, 12 capacitors and 3 resistors. 

Casio H-1B Calculator

Key logic aspects:

  • C clears last entry, AC clears everything
  • 9 digit overflow ignored, no error
  • Overflow error shows E in first digit
  • Divide by zero gives unrecoverable E error
  • Constant on all functions using double operator press
  • Square roots of negative numbers allowed
  • AC also clears memory
  • No memory store indication, user must track
  • Negative number sign limits to 7 digits

Overall, the Casio H-1 is a capable early handheld calculator with the slim styling characteristic of the brand. The lack of a 9th digit and small negatives are drawbacks. But it provides square roots and memory in a pocketable design.

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