The computer systems components are commonly housed in a metallic or plastic case. The internal components remained abstract to us, the computer users. However, these internal components are the parts that actually made up a computer system.
Among the internal components, there some that computer will never run if either of them is absent such as the processor, RAM, or power management device.
In this article, we are going to read about the computer internal components that are very significant in the system, how they operate, and the technology they are used and made from.
MOTHERBOARD
Without a doubt, the most important component in a PC system is the main board often called motherboard, system board, or planar. The motherboard is the computer's main circuit board. It's a thin plate that holds the CPU, memory, connectors for the hard drive and optical drives, expansion cards to control the video and audio, network interface card, and connections to the computer's ports (such as USB ports). The motherboard connects directly or indirectly to every part of the computer. Virtually, every internal component in a PC connects to the motherboard, and its features largely determine what the computer is capable of, not to mention its overall performance.
SYSTEM BUS
A bus is a common pathway across which data can travel within a computer, it carries signals between the components. This pathway is used for communication and can be established between two or more computer elements.
The Personal Computer has a hierarchy of different buses. Most modern PCs have at least three buses - some have four or more. They are hierarchical because each slower bus is connected to the faster one above it. Each device in the system is connected to one of the buses, and some devices act as bridges between the various buses. The main buses that are found in a modern system are as follows:
- Processor bus: Also called the front side bus or FSB, is the highest-speed bus in the system and is at the core of the chipset and motherboard. This bus is used primarily by the processor to pass information to and from cache or main memory and the North Bridge of the chipset.
- Accelerated Graphic Ports (AGP) bus: This is a 32-bit bus designed specifically for a video card. It runs at 66MHz (AGP 1x), 133MHz (AGP 2x), 266MHz (AGP 4x), or 533MHz (AGP 8x), which allows for a bandwidth of up to 2,133MBps. It is connected to the North Bridge or Memory Controller Hub of the chipset and is manifested as a single AGP slot in systems that support it. Current systems have phased out AGP slots in favour of PCI Express.
- Peripheral Components Interconnects (PCI) bus: This bus is generated by either the chipset North Bridge in North/South Bridge chipsets or the I/O Controller Hub in chipsets using hub architecture. This bus is manifested in the system as a collection of 32-bit slots, normally white in colour and numbering from one to three on most motherboards.
- PCI Express (PCIe): PCI Express is a faster development of the PCI bus. PCI Express is a differential signalling bus that can be generated by either the North Bridge or South Bridge. The speed of PCI Express is described in terms of lanes. Each bidirectional dual-simplex lane provides a 2.5Gbps or 5Gbps (PCIe version 2) transfer rate in each direction (250MBps or 500MBps effective speed).
The skeleton of a recent desktop personal computer, showing the typical components and interfaces that are found on the motherboard.
Traditional North/South Bridge Architecture
Most of the PC’s earlier chipsets, use a multitiered architecture incorporating what are referred to as North and South Bridge components, as well as a Super I/O chip:
- The North Bridge: So named because it is the connection between the high-speed processor bus and the slower AGP and Peripheral Component Interconnect (PCI) buses. The North Bridge is what the chipset is named after, meaning that, for example, what its call the 440BX chipset is derived from the fact that the actual North Bridge chip part number for that set is 82443BX.
- The South Bridge: So named because it is the bridge between the PCI bus (66/33MHz) and the even slower Industry Standard Architecture - ISA bus (8MHz).
- The Super I/O chip: It’s a separate chip attached to the Industry Standard Architecture (ISA) bus that is not really considered part of the chipset and often comes from a third party, such as National Semiconductor or Standard Micro Systems Corp. (SMSC). The Super I/O chip included commonly used peripheral items combined into a single chip.
Consequently, chipsets from Intel began using hub architectures in which the former North Bridge chip is now called a Memory Controller Hub (MCH) or an I/O Hub (IOH) and the former South Bridge is called an I/O Controller Hub (ICH). The hub design offers several advantages over the conventional North/South Bridge design, such as fastness, reduced PCI loading, and reduction in bus wiring.
CENTRAL PROCESSING UNIT
The brain or engine of any computer system is the processor - sometimes called microprocessor or central processing unit (CPU). The CPU performs the system’s calculations and processing. The processor is one of the most expensive components in the computer system.
Intel is generally the first corporation credited with creating the first microprocessor in 1971. Up to today, Intel still has control over the processor market, at least for PC systems, although AMD has garnered a respectable market share. Though, some other CPU manufacturers are coming up in the market, such as NVIDIA, VIA, Samsung, Motorola, Qualcomm, and Apple Inc. For the most part, PC-compatible systems use either Intel processors or Intel-compatible processors from AMD.
Processor Specifications
Processors can be identified by two main parameters - that’s how wide they are and how fast they are. The speed of a processor is a fairly simple concept. Speed is counted in megahertz (MHz) or gigahertz (GHz), which means millions or billions, respectively, of cycles per second. The three main specifications in a processor are expressed in width, which are:
- Data (I/O) bus: Also called Front Side Bus (FSB), are lines that carry data to and from the memory. It is a bidirectional bus with width equal to word length of the microprocessor.
- Address bus: The address bus is the set of wires that carry the addressing information used to describe the memory location to which the data is being sent or from which the data is being retrieved.
- Internal Registers (Internal Data Bus): The size of the internal registers indicates how much information the processor can operate on at one time and how it moves data around internally within the chip. This is sometimes also referred to as the internal data bus. A register is a holding cell within the processor - for example, the processor can add numbers in two different registers, storing the result in a third register.
Front and Back view of a Personal Computer Processor (CPU).
Image credit: [PC choice computers] https://pc-choice.com.au/components-computer-motherboard/
MAIN MEMORY - RAM
The system memory, often called RAM (for random access memory), is a temporary storage area where the programs and data being operated on by the processor must reside. Memory storage is considered temporary because the data and programs remain there only as long as the computer has electrical power or is not reset. This type of memory is called RAM, because the locations in the memory can be randomly accessed.
Physically, the main memory in a system is a collection of chips or modules containing chips that are usually plugged into the motherboard. The three (3) main types of physical memory that are used in modern PCs includes the following:
- Read-only memory (ROM): Is a type of memory that can permanently or semi permanently store data. It is called read-only because it is either impossible or difficult to write to. ROM also is often referred to as non-volatile memory because any data stored in ROM remains there, even if the power is turned off.
Illustration of a Read-only Memory (ROM) mounted on a board.
- Dynamic RAM (DRAM): Is the type of memory chip used for most of the main memory (RAM) in a current PC design. This type of memories are volatile, they retain information only if there is electrical current present in the system.
Example of writable volatile random-access memory: Synchronous Dynamic RAM modules for Personal Computer.
IMAGE Credit: By An-d - Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=27224495
- SRAM (Cache memory): Is a high-speed memory buffer that temporarily stores data the processor needs, allowing the processor to retrieve that data faster than if it came from main memory. Static RAM (SRAM) memory is integrated into the processor die.
People new to computers often confuse main memory (RAM) with disk storage because both have capacities that are expressed in similar megabyte or gigabyte terms. The analogy is that, a RAM temporarily stores programs when they are running, along with the data being used by those programs. RAM chips are sometimes termed volatile storage because when you turn off your computer or an electrical outage occurs, whatever is stored in RAM is lost unless you saved it to your hard drive. Whereas, the disk storage serves as a file cabinet, that can be used to store files and data permanently for several years.
HARD DISK DRIVE
The hard disk drive is the primary high-capacity storage media for the computer system. It is a sealed unit used for non-volatile data storage. Non-volatile, or semipermanent, storage means that the storage device retains the data even when there is no power supplied to the computer system.
Image of a Hard Disk Drive.
HDDs contain rigid, circular platters, usually constructed of aluminium or glass. The platters can’t bend or flex - hence the term hard disk. In most drives, the platters are non-removable, which is why they are sometimes called fixed disk drives.
Diagram labeling the major components of a computer Hard Disk Drive (HDD)
Image credit: By I, Surachit, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=4275514
COMPONENTS OF HARD DISK DRIVES
The basic components of a typical HDD include the followings:
- Disk platters (Disks)
- Read/write heads
- Head actuator mechanism
- Spindle motor (inside platter hub)
- Logic board (controller or Printed Circuit Board)
- Cables and connectors
- Configuration items (such as jumpers or switches)
The platters, spindle motor, heads, and head actuator mechanisms usually are contained in a sealed chamber called the head disk assembly (HDA). The HDA is usually treated as a single component - it is rarely opened. Other parts external to the drive’s HDA, such as the logic boards, bezel, and other configuration or mounting hardware, can be disassembled from the drive.
HOW HARD DISKS OPERATE?
The physical design of a Hard Disk Drive consists of spinning disks with heads that move over the disks and store data in tracks and sectors. The heads read and write data in a concentric rings called tracks, which are divided into segments called sectors that typically store 512 or 4,096 bytes each.
Hard Disks usually have multiple disks, that are stacked on top of each other and spin in unison, each with two sides on which the drive stores data. Most drives have two or three platters, resulting in four or six sides, but some Personal Computer hard disks have had up to 12 platters and 24 sides with 24 heads to read them. The identically aligned tracks on each side of every platter together makes up a cylinder. A Hard Drive usually has one head per platter side, with all the heads mounted on a common carrier device or rack. The heads move radially across the disk in unison - they can’t move independently because they are mounted on the same carrier or rack - an actuator.
SOLID STATE DRIVE (SSD)
A recently another high-speed and high-capacity primary storage media for computer system is called Solid State Drive.
A solid-state drive (SSD), sometimes called a semiconductor storage device, a solid-state device or a solid-state disk, is a solid-state storage device that uses integrated circuit assemblies to store data persistently, typically using flash memory, and functioning as secondary storage in the hierarchy of computer storage. SSDs store data in semiconductor cells.
While traditional hard disk drives used spinning platters technology to read and write data, which makes it a little slower for such operations, Solid State Drives (SSDs) use newer technology that stores data on instantly accessible memory chips.
SSDs are typically more resistant to physical shock, run silently, faster, smaller, consume less energy, and have higher input/output rates and lower latency. HDDs are cheaper and offer easier data recovery if damaged.
SSDs can use traditional HDD interfaces and form factors, or newer interfaces and form factors that exploit specific advantages of the flash memory in SSDs. Traditional interfaces (e.g. SATA and SAS) and standard HDD form factors allow such SSDs to be used as drop-in replacements for HDDs in computers and other devices.
mSATA SSD with an external enclosure
Image Credit: By <a href="https://www.wikidata.org/wiki/Q15080600" class="extiw" title="d:Q15080600"><span title="German civil engineer and photographer">Ralf Roletschek</span></a> - <span class="int-own-work" lang="en">Own work</span>, GFDL 1.2, Link
Until the late 2000s, when you bought a new hard disk drive or personal computer, your hard disk storage choices were limited to size and speed — perhaps 5,400 or 7,200 rotations per minute. Today, when you buy a new PC, you have two very different options: you can get one with an SSD or one with an HDD.
POWER SUPPLY UNIT
The power supply unit supplies electrical power to every other component in the system. The basic function of the power supply is to convert the electrical power available at the wall socket to that which the computer circuitry can use. The power supply in a conventional desktop system is designed to convert either 120V (nominal) 60Hz AC (alternating current) or 240V (nominal) 50Hz AC power into +3.3V, +5V, or +12V DC (direct current) power. The power supply must deliver a good, steady supply of DC power so the system can operate properly.
In addition to supplying electrical power to run the system, the power supply ensures that the system does not run unless the voltages supplied are sufficient to operate the system properly. In other words, the power supply actually prevents the computer from starting up or operating until all the power supply voltages are within the proper ranges.
The power supply completes internal checks and tests before allowing the system to start. If the tests are successful, the power supply sends a special signal to the motherboard. This signal must be continuously present for the system to run. Therefore, when the AC voltage dips and the power supply can’t maintain outputs within regulation tolerance, this signal is withdrawn (goes low) and forces the system to reset. The system does not restart until the signal returns to normal operating voltage. All This happens by an intelligently constructed chip in the system called the Power Good or Power OK Signal.
An ATX power supply unit for Desktop Computer with the top cover removed.
Image credit [psu]: Public Domain, https://commons.wikimedia.org/w/index.php?curid=84957
Display Adapter
A video display adapter provides the interface between the computer and the monitor, and it transmits the signals that appear as images on the display. The Graphic adapter controls the information seen on the monitor. The Display adapter also called the video card, graphics adapter, or graphics processing unit [GPU], this often refers to an adapter card plugged into a slot, the video adapter circuitry might also be built into the motherboard or included as part of the motherboard’s chipset. Although it sounds strange, the circuitry is still called an adapter or card even if it is fully integrated into the motherboard, chipset, or processor.
The video display adapters contain certain basic components, which include the followings:
- Video basic input/output system (BIOS): It Provides the firmware controlling the video card.
- Video processor/video accelerator: Places text or graphics information on the screen, and provides 3D acceleration.
- Video memory: Holds the information of an objects that was going to be display on the screen.
- Digital-to-analog converter (DAC): The DAC is usually incorporated into the video processor/accelerator chip. The DAC is not necessary on a purely digital subsystem (digital video card and display) - however, most display subsystems still include analog VGA support.
- Bus connector: This Connects a discrete video card to the motherboard.
- Video driver: It is the Software that communicates with the Operating System (OS) to control the Graphic card.
PC Video Adapter/Card.
Image credit: courtesy of NVIDIA Corporation
SOUND CARD
A sound card - also known as an audio card is an internal expansion card that provides input and output of audio signals to and from a computer under control of a written instructions executed by computer called hardware driver, usually comes with an Operating System. The term sound card is also applied to external audio interfaces used for professional audio applications.
Sound functionality can also be integrated onto the computer motherboard, using components similar to those found on plug-in cards. The integrated sound system is often still referred to as a sound card. Sound processing hardware is also present on the recent graphic cards to output sound along with the video using that connector.
A VIA Technologies Envy sound card for PC, 5.1 channel for PCI slot.
Image credit [sound card]: By Julianprescott2604juuly - Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=36894441
Typical uses of sound cards or sound card functionality include providing the audio component for multimedia applications such as music composition, editing video or audio, presentation, education and entertainment (games) and video projection. Sound cards are also used for computer-based communication such as voice over Internet Protocol - VOIP and in teleconferencing.
NETWORK INTERFACE CARD
A Network Interface Card (NIC, also known as a network interface controller, network adapter, LAN adapter or physical network interface) is a computer hardware component that connects a computer to a computer network. The low cost and availability of the Ethernet standard means that most newer computers have a network interface built into the motherboard.
The network controller implements the electronic circuitry required to communicate using a specific physical layer and data link layer standard such as Ethernet or Wireless Frequencies (Wi-Fi). This provides a base for a full network standard, allowing communication among computers on the same local area network (LAN) and large-scale network communications through routable protocols, such as Internet Protocol (IP).
The NIC allows computers to communicate over a computer network, either by using cables or wirelessly. The NIC is both a physical layer and data link layer device, as it provides physical access to a networking medium.
Technotech Peripheral Components Interconnect (PCI) Local Area Network - LAN Card Network Adapter.
Computer consisted of several internal components that makes it executes tasks efficiently. These components played a very crucial important aspect in computing. The processor device that served as a brain of the computer machine, carried out all the processing tasks, and also controls the other hardware components connected to the computer.
The two types of memories in the computer, the main/primary memory that consisted of RAM plays a significant role in the system by holding the data and information we are currently working on in the computer. The other type of memory in the computer called secondary memory or storage device, hold our data permanently even if there is no electricity in the system or after shutting down the computer. It can also store data for a very long period of time. SSD and HDD are capable of keeping data for over a years or over a decades.
All the internal components of computer are connected to the mainboard. The mainboard all the devices and it also provides a pathway for transporting data and electrical signal among the components. Also, the features of motherboard determined what the system can do.