Computer Hardware Explained

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Computer Hardware Explained


Input devices come in a wide range of shapes, sizes and functions but they all share the same purpose. The input data gathered from real life that humans either see, hear or touch and convert it into digital data which the computer understands. For example, a scanner inputs an object, usually a document that a human can see and touch, and converts it into digitally coded pixels that the computer can understand in order to process, edit or send over digital networks.

Another example would be weather-monitoring devices that measure humidity, wind, temperature, sunlight and much more. These devices are essential for enabling humans to analyse and calculate the world around us in order to help us understand and predict our own environment. Without these, a human would not be able to create a useful working computer.


Output devices share the same purpose of input devices; they enable the communication between computers and humans but in the opposite manner of input devices. For example, a set of speakers or headphones output digitally coded sounds as sound waves so that a humans eardrum can absorb the sound and therefore send the signal to the brain in a form it understands. Without these output devices, a computer would be useless to a human as we wouldn’t be able to understand it.


The main storage device within a computer system is the hard drive, these are mainly disk drives however solid state drives are becoming much more common due to their rapid read/write speeds and durability.

The hard drive usually consists of a spinning magnetic disk contained within a sealed airtight environment. As the disc spins a small electromagnet arm hovers over the disc to read and write binary data. The data is stored in a random-access method that allows any segment of data to be read at any time rather than reading the disk sequentially similar to traditional CDs and DVDs. Disk hard drives, however, are fragile and can easily be destroyed by large shocks or magnets.

The solid-state drive also stores binary data, 0’s and 1’s, however it uses completely different infrastructure to do so. It stores the data in the form of flip-flops across digital logic circuits that can only ever be in one state or two. Flip-flops maintain their state even when the disk drive loses power so the data can be stored and the machine can be switched off.

The state of the flip-flops are changed when electrical triggers are received, however, the digital circuit only has a set lifetime of flip-flops before it becomes worn and unusable. Despite this solid-state drives are on the increase and are becoming more and more popular mainly due to the rapid read/write speeds, for example, a Samsung 850 EVO SSD can read at speeds up to 540MB per second and write up to a speed of 520MB per second. Another factor is price, when solid-state drives first hit the market they were an unaffordable luxury for most people but as technology has progressed their price has come down to a reasonable level making a solid-state drive upgrade worthwhile.


There are three main types of memory within a normal computer system as each has different characteristics in order to fulfil its role as efficiently as possible. These three types are ROM, SRAM and DRAM.

ROM, which stands for read-only memory is not editable once programmed. It also stores data in a random access method, which means any part of data can be accessed at any position on the memory at any time. ROM is also non-volatile which allows data to be retained even when the memory loses power. Due to these characteristics, ROM is commonly used in BIOS chips planted on motherboards of computer systems. These chips are programmed with the basic coding to self-test and start all the components of a fully working computer system before booting the operating system from the storage device.

SRAM, which stands for static random access memory, is extremely fast memory that does not need to be refreshed constantly like DRAM; this enables access speeds as low as 10 nanoseconds. SRAM is volatile memory so unlike ROM it loses its contents when power is lost. SRAM is commonly located alongside a CPU as a memory cache to hold small but valuable processing data whilst the CPU processes other binary data. Due to its complicated manufacturing process and its requirement to be fabricated with much more silicon than other memory types SRAM is expensive and therefore isn’t usually used for large capacity stores. For example, a 64Mbit chip can cost £51.00 and a 1TB hard drive only costs £44.24.

DRAM stands for dynamic random access memory and allows data to be randomly accessed at any location within the memory at any time. DRAM stores its binary data in the form of capacitors on individual circuits, the capacitor is either charged or not charged and so forth these two states represent the 0 and 1 values. The DRAM is volatile and so forth loses all data stored when powered down. Due to the way it stores bits in capacitors DRAM needs to be consistently refreshed in order to store the data; this process is called refreshing. This type of memory is usually used to store the working data of active applications and operating systems that are currently being used on the computer system. DRAM speeds range from 1066MHz to 2400MHz. This speed enables a much faster response time for the software to read active data required to run as opposed to using conventional storage devices such as optical drives.

Processing Sections

A CPU or computer processing unit is an essential component of any computer system. A CPU controls all the algorithmic calculations required for a PC to function, it processes all electronic binary signals of off/on to 0’s/1’s in order to then translate and use that data across the components and peripherals of a computer system. A CPU is made up of three distinct parts, the ALU or arithmetic logic unit, computer hardware registers and the main control unit.

The control unit’s purpose within a CPU is simply to control, it’s the dictator and communicator of the computer. The control unit communicates with the memory, logic unit and input/output devices to control how the components respond to tasks created by the software. It then takes these instructions and converts them into commands to pass to the ALU for calculation.

The ALU is often considered the main “brain” of the CPU as it processes all of the mathematical calculations required. It’s the last segment of the processor to perform calculations as it takes operands and code from the control unit to complete operations for input data. When complete it feeds the results of the calculations back into the memory to then be passed to the control unit again to comprise further instructions for more calculations. However, the processing power of the CPU is all dependent on the size of the register.

The register is the organiser of the CPU, it orders the bits into calculable sizes that the control unit and ALU understands. In the early days of computing, registers were just 8-bits in size however in today’s modern world most computer systems are running 32-bit and 64-bit registers that have increased computing power considerably. For example, a system built with a 32-bit register within its CPU can only ever understand 32-bit components and sizes up to 4GB’s. So if an 8GB DRAM module was installed on a 32-bit register architecture motherboard it would only understand up to 4GB’s of it.

Other than the main CPU in a computer system there is also the North Bridge and the South Bridge, which are installed on the motherboard to act as data “bridges” to the processor. These data bridges are required to accelerate the bit rate of components and peripherals for the data to be compatible for processing by the CPU at around 3.2GHz. The North Bridge is usually located close to the CPU on the motherboard and accelerates, then passes data from the RAM modules (1333 MHz) and graphics card (1300MHz) to the CPU and back again through the same bridge. The South Bridge performs a similar job only it reports to the North Bridge as opposed to the CPU. This is because the South Bridge communicates with slower components and interfaces, such as USB 3.0 (5Gb/s), PCI(10Gb/s), SATA(5Gb/s), Ethernet (100Mb/s) and Audio cards (320Kb/s) that it accelerates for the North Bridge.


The case of a computer system offers a simple but essential job for all types of the system whether it be, mobile, micro, mini or mainframe. The case creates the structure of which the components can safely be cradled within offering stable protection to the system and to the user. In micro desktop systems, there are two main forms of the case, ATX and Micro ATX. These two sizes allow for the standardisation of motherboards and optical drive sizes.


As its name suggests the motherboard is the mother of all the internal components of a computer system. It’s a digital printed circuit that houses and connects components to each other such as the CPU, PCI cards, optical drives, storage and memory along with all external data interfaces such as USB, FireWire and PS/2. The connections between all of these components are called busses and they operate at the same bit rate as the processor to allow compatibility.

Power Supply

A PSU or power supply unit is critical for a computer to function as their circuitry only understands and runs on direct current (DC) so forth the PSU converts mains alternating current (AC) into direct current. Power supplies come in a range varying wattage from 400W up to 1KW depending on the number and power of the internal components. For example, a high-end gaming PC with multiple optical drives, hard drives and graphics cards would require a significantly greater wattage from its power supply to run all of the components properly.

Sound Card

Sound cards within computer systems allow digital data to be converted into real-life sound waves when using an external set of speakers/headphones. They vary from a simple 2 channel AUX socket to 2.1, 5.1 and 7.1 surround sound ports and are usually either built into the motherboard or come as a separate removable PCI card. This enables humans to hear digitally stored music.

Graphics Card

Graphics cards are one of the most demanding and high-performance components of computer systems as a vast amount of processing power is needed to decode data into a form of pixels that the human eye can see. This data is then usually passed through an interface such as HDMI, DVI or VGA to then be displayed on a monitor to the user. Many graphics processing units are built-in to the motherboard or CPU on lower end PC’s and laptops to save production costs, however, most desktops have the ability to install a high-performance graphics card via the PCI interface. These higher performance cards often hold their own memory modules and processing units for faster performance, for instance, this NVIDIA Geforce GT 74O comes with 2GB of DDR3 memory and a graphics processor capable of speeds up to 1059MHz.

Network Interface

A computer system usually contains a network interface of some kind, as without it the system would be extremely limited to the preinstalled functions and software. When networked to other computers using the World Wide Web computers can be powerful machines delivering data and resources from around the world in a matter of seconds. As humans, this is brilliant for the sharing and collaboration of knowledge to educate and discover. Due to these reasons, a network interface has now become essential for most computer systems and usually come in the form of Ethernet sockets built into motherboards, Wi-Fi cards attached to PCI slots or mobile antennas to access a cellular data network. Commonly only Wi-Fi adapters and mobile antennas are used in mobile devices as hard-wired Ethernet becomes less and less popular due to its fixed point limitation.


As described above computers are useless without peripherals, which enable humans to understand and interact with computer systems. There are many types of peripherals for many different reasons, some of which are listed below:

  • Printer: Outputs digital data in a form that can be physically touched and read from a real life object i.e. paper.
  • Camera/Scanner: Translates real-life images, which humans can see, into the code to be inputted into computer systems.
  • Monitor: Outputs digitally coded images in a form of which the human eye can see.
  • Keyboard: Translates and inputs letters and symbols into binary data that the computer understands.
  • Mouse: Translates physical movements by humans into digital binary data that the computer is programmed to understand as gesture commands

Each one of these peripherals has become well known as some of the most common ways of communicating with computer systems in order to input/output data for the benefit of humankind. As you can see from the below graph the forecasted expenditure on peripherals over the years stays roughly the same as these are a required necessity for most people using computer systems.

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