Casio Personal-8

Casio Personal 8 Calculator

The Casio Personal-8 is a compact and sleek calculator that exudes a sophisticated design. Measuring 73mm x 125mm x 23mm and weighing a mere 116g without batteries, this calculator boasts a smooth black plastic case with an aluminum inset on the front and sides. Its rounded corners and ridged end sections make it comfortable to hold, while the recessed sticker bearing the Casio logo and name adds a touch of elegance. The neutral and flat display filter ensures a clean and bright image, and the squishy yet responsive buttons are a hallmark of Casio’s quality.

Casio Personal 8 Calculator

Powering the Casio Personal 8 are two AA batteries or an optional AD-2S 3V 0.2W adapter, which can be connected through a socket on the top right side. The calculator features an 8-digit blue VFD display without a ninth digit, providing a clear and easy-to-read interface.

Under the hood, the Casio Personal 8 is equipped with a Hitachi HD3679 5A53 28-pin DIL CPU, a single-tube round-face NEC LD8120 VFD display, seven capacitors, four resistors, three resistor arrays, and a Fuji MPS 0606 5A-22 transformer module (patent number 427559). The keyboard assembly (A8S-E4A) is connected to the floating main CPU board (A8R-1B) via 12 sturdy wires, ensuring reliable operation.

Casio Personal 8 Calculator

Disassembling the calculator is a straightforward process: simply remove the screw from the battery compartment, gently pop the lugs on the left and right sides, and the rear section will lift away, providing access to the internals.

Casio Personal 8 Calculator Box


  • The (C) button clears the last entered number, while the (AC) button clears the entire calculator.
  • Overflow on number input is suppressed, and keying in a ninth digit is ignored.
  • An overflow error is indicated by an “E” in the far-right (first) digit and is not recoverable.
  • Divide by zero also results in an unrecoverable “E” in the far-right digit.
  • Automatic constant is enabled for all functions.
  • Negative numbers are flagged by a “-” sign in the immediate left digit, limiting negative numbers to seven digits.
  • The calculator exhibits the “negative zero bug”: keying in (0)(-)(1)(=) to give “-1”, followed by (+1)(=), will result in “-0”.
  • It also suffers from the divide-to-zero bug: keying in (-)(1)(=) to give “-1”, followed by (/)(1)(0)(=)(=)(=), etc., will eventually result in “-0”.
Casio Personal 8 Calculator Back

The Casio Personal-8 is a well-designed and compact calculator from 1975, boasting a sleek appearance and a respectable set of features for its time. While its logic has some quirks and limitations, it remains a notable entry in Casio’s early calculator lineup.

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