The Anita 810 was an advanced handheld calculator released in the early 1970s by the Sumlock Comptometer company in the United Kingdom. With its sleek and modern design, the Anita 810 stood out among the bulky calculators of its time.
At around 70mm x 120mm x 23mm, the Anita 810 had a compact rectangular shape that made it easily portable. Despite its small size, it packed impressive capabilities into its three internal circuit boards connected by wires. The calculator was powered by three AA batteries or could run off an AC adapter.
The Anita 810 featured an eight-digit red LED display, allowing it to show full eight-digit negative numbers thanks to a dedicated minus sign indicator. Input overflow was silently suppressed, letting the user enter long numbers without issue. The display could also show up to two decimal places when enabled.
Beyond basic arithmetic, the Anita 810 implemented constant calculation across all four math functions. It had early support for Reverse Polish Notation (RPN) input, a style popular among technical users. The calculator could round results up or down to two decimal places.
The Anita 810’s case was as innovative as its electronics. It used a two-tone plastic body with a unique sliding metal back plate. An aluminum panel on the front provided markings for the key functions. The design gave it an aesthetic rarely seen in affordable calculators.
Inside, the Anita 810 utilized cutting-edge semiconductor technology. Its central processing unit was a 1974-era Rockwell chip containing the entire calculator logic. Supporting it were various diode, transistor and capacitor components that handled the display, math and interface.
With its forward-looking design and functionality, the Anita 810 showed the potential of handheld calculators. It pioneered features like RPN input and multi-board construction well before they became common. The Anita 810 demonstrated that pocket calculators could be both highly practical and stylistically elegant.