1) The trackball, a related pointing device, was invented in 1946 by Ralph Benjamin as part of a post-World War II-era fire-control radar plotting system called the Comprehensive Display System (CDS). Benjamin was then working for the British Royal Navy Scientific Service. Benjamin’s project used analog computers to calculate the future position of target aircraft based on several initial input points provided by a user with a joystick. Benjamin felt that a more elegant input device was needed and invented what they called a “roller ball” for this purpose.^[9][10]

The device was patented in 1947,^[10] but only a prototype using a metal ball rolling on two rubber-coated wheels was ever built, and the device was kept as a military secret.^[9]

Another early trackball was built by Kenyon Taylor, a British electrical engineer working in collaboration with Tom Cranston and Fred Longstaff. Taylor was part of the original Ferranti Canada, working on the Royal Canadian Navy‘s DATAR (Digital Automated Tracking and Resolving) system in 1952.^[11]

DATAR was similar in concept to Benjamin’s display. The trackball used four disks to pick up motion, two each for the X and Y directions. Several rollers provided mechanical support. When the ball was rolled, the pickup discs spun and contacts on their outer rim made periodic contact with wires, producing pulses of output with each movement of the ball. By counting the pulses, the physical movement of the ball could be determined. A digital computer calculated the tracks and sent the resulting data to other ships in a task force using pulse-code modulation radio signals. This trackball used a standard Canadian five-pin bowling ball. It was not patented, since it was a secret military project.^[12][13]

2) Is making a record of each key that is pressed. Keystroke logging can be used to measure employee activity. Hackers can also use keystroke logging to get private information, such as passwords. This can be done by putting a piece of hardware in the keyboard or on the cable, or by installing malware in the computer. A wireless keyboard makes it especially easy for the hacker to detect the wireless signals.^[1][2]

The use of any keyboard may cause repetitive strain injury to the hands, wrists, arms, neck or back.^[3] The risks of injuries can be reduced by taking frequent, short breaks to get up and walk around, a couple of times every hour. Users should also vary tasks throughout the day, to avoid overuse of the hands and wrists. When using a keyboard, a person should keep the shoulders relaxed with the elbows at the side, with the keyboard and mouse positioned so that they are comfortable to use. The chair height and keyboard should be adjusted so that the wrists are straight, and not resting on sharp edges of tables or the computers themselves.^[4] Some technology ranging from special keyboards to pen-tablet interfaces or speech recognition software can reduce the risk of injury. Pause software reminds the user to pause frequently.

Researchers are studying if keyboards can spread diseases. Some keyboards were found to contain five times more germs than a toilet seat.^[5]

3) A motherboard (also called mainboard, main circuit board, MB, base board, system board, or, in Apple computers, logic board) is the main printed circuit board (PCB) in general-purpose computers and other expandable systems. It holds and allows communication between many of the crucial electronic components of a system, such as the central processing unit (CPU) and memory, and provides connectors for other peripherals. Unlike a backplane, a motherboard usually contains significant sub-systems, such as the central processor, the chipset‘s input/output and memory controllers, interface connectors, and other components integrated for general use.

Motherboard means specifically a PCB with expansion capabilities. As the name suggests, this board is often referred to as the mother of all components attached to it, which often include peripherals, interface cards, and daughterboards: sound cards, video cards, network cards, host bus adapters, TV tuner cards, IEEE 1394 cards, and a variety of other custom components.

Similarly, the term mainboard describes a device with a single board and no additional expansions or capability, such as controlling boards in laser printers, television sets, washing machines, mobile phones, and other embedded systems with limited expansion abilities.

4) A graphics card (also called a video card, display card, graphics accelerator, graphics adapter, VGA card/VGA, video adapter, display adapter, or colloquially GPU) is a computer expansion card that generates a feed of graphics output to a display device such as a monitor. Graphics cards are sometimes called discrete or dedicated graphics cards to emphasize their distinction to an integrated graphics processor on the motherboard or the central processing unit (CPU). A graphics processing unit (GPU) that performs the necessary computations is the main component in a graphics card, but the acronym “GPU” is sometimes also used to erroneously refer to the graphics card as a whole.^[1]

Most graphics cards are not limited to simple display output. The graphics processing unit can be used for additional processing, which reduces the load from the CPU.^[2] Additionally, computing platforms such as OpenCL and CUDA allow using graphics cards for general-purpose computing. Applications of general-purpose computing on graphics cards include AI training, cryptocurrency mining, and molecular simulation.^[3][4][5]

Usually, a graphics card comes in the form of a printed circuit board (expansion board) which is to be inserted into an expansion slot.^[6] Others may have dedicated enclosures, and they are connected to the computer via a docking station or a cable. These are known as external GPUs (eGPUs).

Graphics cards are often preferred over integrated graphics for increased performance.

5) A hard disk drive (HDD), hard disk, hard drive, or fixed disk^[a] is an electro-mechanical data storage device that stores and retrieves digital data using magnetic storage with one or more rigid rapidly rotating platters coated with magnetic material. The platters are paired with magnetic heads, usually arranged on a moving actuator arm, which read and write data to the platter surfaces.^[1] Data is accessed in a random-access manner, meaning that individual blocks of data can be stored and retrieved in any order. HDDs are a type of non-volatile storage, retaining stored data when powered off.^[2][3][4] Modern HDDs are typically in the form of a small rectangular box.