Casio J-3

Casio J-3 Calculator

The Casio J-3 calculator, also known as the J-1211, was an innovative desktop calculator introduced in 1978 by the Japanese electronics company, Casio Computer Co., Ltd. With its large size and distinctive design, the J-3 calculator was a standout product that catered to the needs of the office market.

Casio J-3 Case

The calculator has an impressive 12-digit blue VFD display, with an additional thirteenth digit for indicating negative numbers, memory status, and error messages. The display’s thousand separators added a touch of clarity and professionalism to the numerical output. The calculator’s case was a two-piece design, combining cream and very dark brown smooth plastic, with a brushed aluminum keyboard surround printed with black text. The large square keys featured Casio’s signature black plastic escutcheons, providing a tactile and responsive user experience.

Casio J-3 Display

Beyond its nice appearance, the Casio J-3 offered a range of essential features for everyday calculations. It supported four basic arithmetic operations, along with percentages, delta percentages, square roots, and the ability to change the sign of a number. Additionally, it boasted a three-function memory, allowing users to store and recall values easily.

However, the J-3 calculator was not without its quirks. It’s display driver consumes batteries relatively quickly. Also, certain operations, such as overflow on number input and division by zero, can result in unrecoverable errors, requiring a reset.

Casio J-3 Box

Under the hood, the Casio J-3 was powered by a Hitachi HD38401A 8M15 CPU, complemented by various components, including a 13-digit NEC F1P display, transistors, diodes, capacitors, resistors, and a TDK transformer. The keyboard board was securely attached to the front panel, connecting to the main CPU board via 24 stiff copper wires and an insulating strip.


  • (C) clears the last entry of a number, while (AC) clears the entire calculator.
  • Typing a thirteen-digit number causes an unrecoverable overflow.
  • An overflow error is indicated by a “C” (“E” if negative) in the thirteenth digit and is recoverable using (C).
  • Division by zero results in an unrecoverable “C” in the thirteenth digit.
  • Automatic constant is available for all functions.
  • Square roots of negative numbers are displayed, but the answer is recoverable using (C).
  • Memory store is indicated by a decimal point in the thirteenth digit.
  • Negative numbers are flagged by a “-” sign in the thirteenth digit, allowing full twelve-digit negative numbers.
  • The “F Cut 5/4” switch toggles floating or fixed decimal point.
  • The decimal places can be set to 4, 2, 1, or 0 using a dedicated switch.
  • The change sign key operates on the displayed number even after a function button is pressed.
  • The (delta %) key can be used for mark-up or mark-down calculations.
Casio J-3  Battery

The Casio J-3 calculator was a robust and feature-rich desktop calculator that catered to the needs of the office market in the late 1970s. Its impressive size, distinct design, and comprehensive functionality made it a notable addition to Casio’s lineup at the time and a very collectible calculator today.

Right Now on eBay 
Clicking a link to eBay may result in a referral commission being paid if a purchase is made.

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.