Computer hardware is the physical part of a computer system that you can touch and see. It includes input devices, output devices, and storage devices.
Input devices allow the user to enter information into the system or control its operation. Output devices display information in a form that is easy to read or hear.
Keyboard
The keyboard is the primary way to input text and other computer commands. Keyboards can be physical devices that sit in the computer case or virtual devices that are part of tablet PCs.
The keys on a keyboard are arranged in a grid called the key matrix. Each key is attached to a switch that completes an electrical circuit.
When a key is pressed, the switch breaks and a small amount of current flows through the circuit. The processor in the keyboard detects this by detecting the scan code that is transmitted when a key is pressed.
The keyboard also has a group of control keys that are used to navigate around the screen by changing the position of the cursor. These keys are usually found between the typing and numeric keypads.
Monitor
A monitor is an output device that displays video and text from a computer. It includes circuitry, a screen, power supply, and buttons to adjust screen settings.
Most modern computer monitors use flat-panel display technology, which is commonly backlit with LEDs. These are thinner and more energy-efficient than their older CRT counterparts.
The contrast ratio of a monitor is one of the most basic measurements, measuring how well the screen can display bright whites and dark blacks. Higher numbers indicate better performance.
Luminance is another key measure, given in “nits” or candelas per square meter. VESA has standardized a suite of tests for luminance, so it’s best to check this against the spec on your monitor.
Response time is a measure of how quickly a monitor’s pixels change from one color to the next. High-quality monitors have fast responses, producing smooth images with no ghosting or blurring effects.
Many gaming monitors, like G-Sync and AMD Radeon FreeSync models, use scaler chips to match their refresh rates with the GPU output of your game, avoiding stutter and tearing.
Hard Drive
Every computer comes with an internal hard drive, which stores your permanent computer data. It can store files from any application on your system and contains a lot of information.
A hard disk drive (HDD) is a type of solid-state storage device that uses magnetic platters to store and retrieve digital information. It can be found in most desktop and laptop computers.
The hard drive works by spinning the disks at a fast rate, allowing data to be read and written quickly. Whenever the computer needs to access data, it will access the drive to get what it needs.
Modern drives have one head for each magnetic surface on the spindle; an actuator (arm) moves this head on an arc across the magnetic platters as they spin. This can take as much as half the rotational period, depending on the bit rate or data transfer rate. This delay is referred to as rotational latency. It is usually not noticeable, but may be significant when large contiguous blocks are transferred.
Power Supply
A power supply is a crucial component of your PC hardware. It converts the alternating voltage (AC) that you get from your home’s electrical system into the DC current that your PC needs to function properly.
A good power supply should have a high efficiency rating, which will save you money in the long run and help prevent overheating. It should also have fans for cooling your components and the unit itself.
Traditionally, power supplies have come with different voltage rails – which is how the power is delivered to various components of your system. For example, a motherboard will draw power from the +12 V rail, while the motors that run your CPU fans will draw from the +5 V rail.
A good power supply will have a power rating that matches the components it’s supplying and should be able to withstand any amount of load. This can be an important consideration, especially when upgrading to new components or if you plan on overclocking your PSU.