Calculator in the context of "Trigonometric table"

An abacus (pl. abaci or abacuses), also called a counting frame, is a hand-operated calculating tool which was used from ancient times, in the ancient Near East, Europe, China, and Russia, until largely replaced by handheld electronic calculators, during the 1980s, with some ongoing attempts to revive their use. An abacus consists of a two-dimensional array of slidable beads (or similar objects). In their earliest designs, the beads could be loose on a flat surface or sliding in grooves. Later the beads were made to slide on rods and built into a frame, allowing faster manipulation.

Each rod typically represents one digit of a multi-digit number laid out using a positional numeral system such as base ten (though some cultures used different numerical bases). Roman and East Asian abacuses use a system resembling bi-quinary coded decimal, with a top deck (containing one or two beads) representing fives and a bottom deck (containing four or five beads) representing ones. Natural numbers are normally used, but some allow simple fractional components (e.g. 1⁄2, 1⁄4, and 1⁄12 in Roman abacus), and a decimal point can be imagined for fixed-point arithmetic.

Solar power, also known as solar electricity, is the conversion of energy from sunlight into electricity, either directly using photovoltaics (PV) or indirectly using concentrated solar power. Solar panels use the photovoltaic effect to convert light into an electric current. Concentrated solar power systems use lenses or mirrors and solar tracking systems to focus a large area of sunlight to a hot spot, often to drive a steam turbine.

Photovoltaics (PV) were initially solely used as a source of electricity for small and medium-sized applications, from the calculator powered by a single solar cell to remote homes powered by an off-grid rooftop PV system. Commercial concentrated solar power plants were first developed in the 1980s. Since then, as the cost of solar panels has fallen, grid-connected solar PV systems' capacity and production has doubled about every three years. Three-quarters of new generation capacity is solar, with both millions of rooftop installations and gigawatt-scale photovoltaic power stations continuing to be built.

Typing is the process of entering or inputting text by pressing keys on a typewriter, computer keyboard, mobile phone, or calculator. It can be distinguished from other means of text input, such as handwriting and speech recognition; text can be in the form of letters, numbers and other symbols. The world's first typist was Lillian Sholes from Wisconsin in the United States, the daughter of Christopher Latham Sholes, who invented the first practical typewriter.

User interface features such as spell checker and autocomplete serve to facilitate and speed up typing and to prevent or correct errors the typist may make.

Consumer electronics, also known as home electronics, are electronic devices intended for everyday household use. Consumer electronics include those used for entertainment, communications, and recreation. Historically, these products were referred to as "black goods" in American English due to many products being housed in black or dark casings. This term is used to distinguish them from "white goods", which are meant for housekeeping tasks, such as washing machines and refrigerators. In British English, they are often called "brown goods" by producers and sellers. Since the 2010s, this distinction has been absent in big box consumer electronics stores, whose inventories include entertainment, communication, and home office devices, as well as home appliances.

Radio broadcasting in the early 20th century brought the first major consumer product, the broadcast receiver. Later products included telephones, televisions, calculators, cameras, video game consoles, mobile phones, personal computers, and MP3 players. In the 2010s, consumer electronics stores often sold GPS, automotive electronics (vehicle audio), video game consoles, electronic musical instruments (e.g., synthesizer keyboards), karaoke machines, digital cameras, and video players (VCRs in the 1980s and 1990s, followed by DVD players and Blu-ray players). Stores also sold smart light fixtures, network devices, camcorders, and smartphones. Some of the modern products being sold include virtual reality goggles, smart home devices that connect to the Internet, streaming devices, and wearable technology.

A transistor is a semiconductor device used to amplify or switch electrical signals and power. It is one of the basic building blocks of modern electronics. It is composed of semiconductor material, usually with at least three terminals for connection to an electronic circuit. A voltage or current applied to one pair of the transistor's terminals controls the current through another pair of terminals. Because the controlled (output) power can be higher than the controlling (input) power, a transistor can amplify a signal. Some transistors are packaged individually, but many more in miniature form are found embedded in integrated circuits. Because transistors are the key active components in practically all modern electronics, many people consider them one of the 20th century's greatest inventions.

Physicist Julius Edgar Lilienfeld proposed the concept of a field-effect transistor (FET) in 1925, but it was not possible to construct a working device at that time. The first working device was a point-contact transistor invented in 1947 by physicists John Bardeen, Walter Brattain, and William Shockley at Bell Labs who shared the 1956 Nobel Prize in Physics for their achievement. The most widely used type of transistor, the metal–oxide–semiconductor field-effect transistor (MOSFET), was invented at Bell Labs between 1955 and 1960. Transistors revolutionized the field of electronics and paved the way for smaller and cheaper radios, calculators, computers, and other electronic devices.

The D-pad (short for directional pad) is a compact input method developed for video games, designed to translate thumb movement into directional control through a flat, cross-shaped surface that rests on four internal switches. Each switch corresponds to a cardinal direction (up, down, left, and right), while diagonal inputs engage two switches simultaneously, enabling eight-directional control at 45-degree intervals. Beneath the center, a pivot mechanism tilts the pad, preventing all four switches from being pressed at once and enhancing tactile feedback.

When introduced, the D-pad offered a space-saving, precise input method at a time when bulky joysticks dominated the market. Although analog sticks have largely superseded D-pads as the primary directional input in modern gamepads, the D-pad's compact, intuitive, and versatile design has led to its adoption in a wide range of devices, including remote controls, calculators, PDAs, mobile phones, and car stereos.