# 4.2 Understanding Computer Hardware ### **4.2 Understanding Computer Hardware** **Weight:** 2 **Description:** Familiarity with the components that go into building desktop and server computers. **Key Knowledge Areas:** * Hardware **The following is a partial list of the used files, terms and utilities:** * Motherboards, processors, power supplies, optical drives, peripherals * Hard drives, solid state disks and partitions, /dev/sd\* * Drivers ## Hardware Components of a Computer \ Hardware Components of a computer refers to the collection of physical parts of a computer\ system that we can touch or feel. This includes the computer case, monitor, keyboard, and\ mouse. It also includes all the parts inside the computer case, such as the hard disk drive,\ motherboard, video card, and many others.\ The hardware components of a computer or personal computer is categorized into 4 primary\ categories: 1. System Unit 2. Display Device 3. Input Devices 4. External Devices 5. System Unit ### 1. System Unit \ A System Unit is the main component of a personal computer, which houses the other devices\ necessary for the computer to function. It is comprised of a chassis and the internal components\ of a personal computer such as the system board (mother board), the microprocessor, memory\ modules, disk drives, adapter cards, the power supply, a fan or other cooling device and ports\ for connecting external components such as monitors, keyboards, mice, and other devices.

System Unit components

### 2. Display Devices A display device is a personal computer component and is an output device that enables user to\ view the text and graphical data associated with a computer program. Display devices\ commonly connect to the system unit via a cable, and they have controls to adjust the settings\ for the device. They vary in size and shape, as well as the technology used.

Display Device

### 3. Input Devices An input device is a personal computer component that enables users to enter data or\ instructions into a computer. The most common input devices are keyboards and computer\ mice. Input devices can connect to the system via a cable or a wireless connection.
### 4. External Devices Any peripherals devices that are not housed inside the system unit are inherently external\ devices. A personal computer’s functionality can be enhanced by connecting different types of\ external devices to the system unit, often called peripherals devices. These devices typically\ provide alternative input or output methods or additional data storage. External devices are\ connected to the system unit via a cable or wireless connection. Some of them have their own\ power source and some draw power from the system. | | | | | --------------------------------------------------------------------------------------------------- | --------------- | -------------------------------------------------------------------------------------- | |
| Microphone | Provides audio input | |
| Digital Camera | Provides graphical input | |
| Scanner | Provides graphical input | |
| Speaker | Provides audio output | |
| Printer | Provides printed output | |
| Network device |

Provides communication with other
computers, such as access to the Internet.

| |
| External device | Provides additional data storage | ### 5. System Unit Components 1. The System Board 2. Central Processing Unit 3. Memory 4. Power Supplies 5. Cooling Systems etc. #### 1. The System Board The system board is the personal computer component that acts as the backbone for the\ entire computer system as it serves as a single platform to connect all of the parts of a computer\ together. It connects the CPU, memory, hard drives, optical drives, video card, sound card, and\ other ports and expansion cards directly or via cables. System Board is also known as\ motherboard. It consists of a large, flat circuit board with chips and other electrical components\ on it.\ Some popular manufacturers of the motherboard are: * Intel * Asus * Gigabyte * Biostar * Msi

System Board or Motherboard

#### 2. Central Processing Unit (CPU) \ The Central Processing Unit (CPU), sometimes called microprocessor or just processor, is\ the real brain of the computer and is where most of the calculations take place.\ Some popular manufacturers / designers of the CPU are: * Intel * AMD * Qualcomm * Media Tek * NVIDIA \ Central Processing Unit (CPU) consists of the following features:
* CPU is considered as the brain of the computer. * CPU performs all types of data processing operations. * It stores data, intermediate results, and instructions (program). * It controls the operation of all parts of the computer.

Central Processing Unit (CPU)

#### 3. memory Memory devices are hardware components that store digital data, categorized as primary (RAM, ROM) for active processing or secondary (HDD, SSD, USB drives, SD cards) for long-term storage, differing in speed, volatility (temporary vs. permanent data retention), and use, from fast volatile RAM for running apps to slow non-volatile drives for files. They work by representing data as binary digits (0s and 1s) using various physical states like voltage, magnetism, or charge. Types of Memory Devices * **Primary Memory (Main Memory)**: Directly accessible by the CPU. * **RAM (Random Access Memory)**: Volatile (loses data without power); used for active programs and data (e.g., DRAM, SRAM). * **ROM (Read-Only Memory)**: Non-volatile; stores permanent instructions like BIOS (e.g., PROM, EPROM, EEPROM). * **Cache**: Very fast, small memory for frequently used data. * **Secondary Storage (Auxiliary Storage)**: Non-volatile, for long-term storage. * **Magnetic**: Hard Disk Drives (HDDs), floppy disks, magnetic tapes. * **Solid-State**: Solid State Drives (SSDs), USB flash drives, memory cards (SD cards, etc.). * **Optical**: CDs, DVDs, Blu-ray discs. Key Characteristics * **Volatility**: Volatile (RAM) vs. Non-Volatile (ROM, SSD, HDD). * **Speed**: Cache > RAM > SSD > HDD > Optical/Tape. * **Storage Capacity**: Varies greatly (GBs in RAM to TBs in HDDs). #### 4. Power Supply Power Supply known as switch-mode power supply (SMPS) is an electronic circuit that\ converts power using switching devices that are turned on and off at high frequencies, and\ storage components such as inductors or capacitors to supply power when the switching\ device is in its non-conduction state.\ Switching power supplies have high efficiency and are widely used in a variety of electronic\ equipment, including computers and other sensitive equipment requiring stable and efficient\ power supply.

SMPS

#### 5. Colling System Cooling may be required for CPU, Video Card, Mother Board, Hard Drive, etc. Without\ proper cooling, the computer hardware may suffers from overheating. This overheating causes\ slow downs, system error messages, and crashing. Also, the life expectancy of the PC's\ components is likely to diminish. The following are commonly used techniques for cooling the\ PC or Server components: * Heat Sinks * CPU/Case Fans * Thermal Compound * Liquid Cooling Systems \ **Heat Sinks:** The purpose of a heatsink is to conduct the heat away from the processor or any\ other component (such as chipset) to which it is attached. Thermal transfer takes place at the\ surface of a heatsink. Therefore, heat sinks should have a large surface area. A commonly used\ technique to increase the surface area is by using fins. A typical processor heat sink is shown\ in the figure below:

intel Dual Core Xenon LGA 771 heatsink

**Fan:** The Fan is primarily used to force cooler air in to the system or remove hot air out of the\ system. A fan keeps the surrounding cooler by displacing air around the heatsink and other parts\ of the computer. A typical CPU fan is shown below.

Heatsink with Fan

**Thermal Compound:** A thermal compound is used for maximum transfer of heat from CPU\ to the heatsink. The surface of a CPU or a heatsink is not perfectly flat. If you place a heatsink\ directly on a CPU, there will be some air gaps between the two. Air is a poor conductor of heat.\ Therefore, an interface material with a high thermal conductivity is used to fill these gaps, and\ thus improve heat conductivity between CPU and heatsink.
\ **Liquid Cooling Systems:** Like a radiator for a car, a liquid cooling system circulates a liquid\ through a heat sink attached to the processor. First, the cooler liquid passes through the heatsink,\ and then gets hot due to transfer of heat from the processor to the heatsink. Then the hot liquid\ passes through the radiator at the back of the case, and transfers the heat to the secondary\ coolant (air). Now, the liquid is cool enough to pass through the hot processor heatsink, and the\ cycle repeats. The chief advantage of LCS (Liquid Cooling System) is that the cooling takes\ place very efficiently (since liquids transfer heat more efficiently than air/solids). The disadvantages include bulkier cooling system, cost, and additional reliability issues associated with\ LCS.
## Device Drivers Drivers are used to help the hardware devices interact with the operating system. In windows, all the devices and drivers are grouped together in a single console called device manager. In Linux, even the hardware devices are treated like ordinary files, which makes it easier for the software to interact with the device drivers. When a device is connected to the system, a device file is created in **/dev** directory. **Most Common types of devices in Linux:** 1. **Character devices** - These devices transmit the data character by characters, like a mouse or a keyboard. 2. **Block devices** - These devices transfer unit of data storage called a *block,* USB drives, hard drives, and CD ROMs To list all the device files use the below command: ``` ls -l /dev ``` ``` [root@earth ~]# whoami root [root@earth ~]# ls -l /dev total 0 crw-------. 1 root root 10, 123 Dec 9 08:52 acpi_thermal_rel crw-r--r--. 1 root root 10, 235 Dec 9 08:52 autofs drwxr-xr-x. 2 root root 340 Dec 9 08:54 block drwxr-xr-x. 2 root root 80 Dec 9 08:54 bsg drwxr-xr-x. 3 root root 60 Dec 9 12:22 bus drwxr-xr-x. 2 root root 4220 Dec 9 15:38 char crw--w----. 1 root tty 5, 1 Dec 9 08:52 console lrwxrwxrwx. 1 root root 11 Dec 9 12:22 core -> /proc/kcore drwxr-xr-x. 10 root root 200 Dec 9 12:22 cpu crw-------. 1 root root 10, 124 Dec 9 08:52 cpu_dma_latency drwxr-xr-x. 9 root root 180 Dec 9 12:22 disk brw-rw----. 1 root disk 253, 0 Dec 9 08:52 dm-0 brw-rw----. 1 root disk 253, 1 Dec 9 08:52 dm-1 drwxr-xr-x. 2 root root 60 Dec 9 12:22 dma_heap drwxr-xr-x. 3 root root 140 Dec 9 08:52 dri crw-rw----. 1 root video 29, 0 Dec 9 08:52 fb0 lrwxrwxrwx. 1 root root 13 Dec 9 12:22 fd -> /proc/self/fd crw-rw-rw-. 1 root root 1, 7 Dec 9 08:52 full crw-rw-rw-. 1 root root 10, 229 Dec 9 08:52 fuse crw-------. 1 root root 254, 0 Dec 9 08:52 gpiochip0 crw-------. 1 root root 242, 0 Dec 9 08:52 hidraw0 crw-------. 1 root root 242, 1 Dec 9 08:54 hidraw1 crw-------. 1 root root 242, 2 Dec 9 08:54 hidraw2 crw-------. 1 root root 10, 228 Dec 9 08:52 hpet drwxr-xr-x. 2 root root 0 Dec 9 08:52 hugepages crw-------. 1 root root 10, 183 Dec 9 08:52 hwrng lrwxrwxrwx. 1 root root 12 Dec 9 08:52 initctl -> /run/initctl drwxr-xr-x. 4 root root 540 Dec 9 15:38 input crw-r--r--. 1 root root 1, 11 Dec 9 08:52 kmsg crw-rw-rw-. 1 root kvm 10, 232 Dec 9 08:52 kvm lrwxrwxrwx. 1 root root 28 Dec 9 12:22 log -> /run/systemd/journal/dev-log crw-rw----. 1 root disk 10, 237 Dec 9 08:52 loop-control crw-rw----. 1 root lp 6, 0 Dec 9 08:52 lp0 crw-rw----. 1 root lp 6, 1 Dec 9 08:52 lp1 crw-rw----. 1 root lp 6, 2 Dec 9 08:52 lp2 crw-rw----. 1 root lp 6, 3 Dec 9 08:52 lp3 drwxr-xr-x. 2 root root 100 Dec 9 08:52 mapper crw-------. 1 root root 10, 227 Dec 9 08:52 mcelog crw-rw----+ 1 root video 237, 0 Dec 9 08:52 media0 crw-------. 1 root root 238, 0 Dec 9 08:52 mei0 crw-r-----. 1 root kmem 1, 1 Dec 9 08:52 mem drwxrwxrwt. 2 root root 40 Dec 9 12:22 mqueue drwxr-xr-x. 2 root root 60 Dec 9 12:22 net crw-------. 1 root root 239, 0 Dec 9 08:52 ng0n1 crw-rw-rw-. 1 root root 1, 3 Dec 9 08:52 null crw-------. 1 root root 240, 0 Dec 9 08:52 nvme0 brw-rw----. 1 root disk 259, 0 Dec 9 08:52 nvme0n1 brw-rw----. 1 root disk 259, 1 Dec 9 08:52 nvme0n1p1 brw-rw----. 1 root disk 259, 2 Dec 9 08:52 nvme0n1p2 crw-------. 1 root root 10, 144 Dec 9 08:52 nvram crw-r-----. 1 root kmem 1, 4 Dec 9 08:52 port crw-------. 1 root root 108, 0 Dec 9 08:52 ppp crw-rw-rw-. 1 root tty 5, 2 Dec 9 15:51 ptmx drwxr-xr-x. 2 root root 0 Dec 9 12:22 pts crw-rw-rw-. 1 root root 1, 8 Dec 9 08:52 random crw-rw-r--+ 1 root root 10, 242 Dec 9 08:52 rfkill lrwxrwxrwx. 1 root root 4 Dec 9 08:52 rtc -> rtc0 crw-------. 1 root root 250, 0 Dec 9 08:52 rtc0 brw-rw----. 1 root disk 8, 0 Dec 9 08:52 sda brw-rw----. 1 root disk 8, 1 Dec 9 08:52 sda1 brw-rw----. 1 root disk 8, 2 Dec 9 08:52 sda2 brw-rw----. 1 root disk 8, 3 Dec 9 08:54 sda3 brw-rw----. 1 root disk 8, 4 Dec 9 08:52 sda4 brw-rw----. 1 root disk 8, 5 Dec 9 08:52 sda5 brw-rw----. 1 root disk 8, 6 Dec 9 08:52 sda6 brw-rw----. 1 root disk 8, 7 Dec 9 08:52 sda7 brw-rw----. 1 root disk 8, 8 Dec 9 11:39 sda8 brw-rw----. 1 root disk 8, 16 Dec 9 08:54 sdb crw-rw----. 1 root disk 21, 0 Dec 9 08:52 sg0 crw-rw----. 1 root disk 21, 1 Dec 9 08:54 sg1 drwxrwxrwt. 2 root root 140 Dec 9 15:51 shm crw-------. 1 root root 10, 231 Dec 9 08:52 snapshot drwxr-xr-x. 3 root root 320 Dec 9 08:52 snd lrwxrwxrwx. 1 root root 15 Dec 9 12:22 stderr -> /proc/self/fd/2 lrwxrwxrwx. 1 root root 15 Dec 9 12:22 stdin -> /proc/self/fd/0 lrwxrwxrwx. 1 root root 15 Dec 9 12:22 stdout -> /proc/self/fd/1 crw-rw----. 1 tss root 10, 224 Dec 9 08:52 tpm0 crw-rw----. 1 tss tss 253, 65536 Dec 9 08:52 tpmrm0 crw-rw-rw-. 1 root tty 5, 0 Dec 9 15:51 tty crw--w----. 1 root tty 4, 0 Dec 9 08:53 tty0 crw--w----. 1 root tty 4, 1 Dec 9 08:53 tty1 crw--w----. 1 root tty 4, 10 Dec 9 08:52 tty10 ``` In the above output, we can see some other types of file types, some of them have **B** for a block device, **C** for character device some devices start with /dev/sda or /sdb. etc. ### /dev/sd\* In Linux, the disk names are alphabetical. For example, dev/sda is the first hard drive, dev/sdb is the second hard drive, and so on. These devices are mass storage devices like memory sticks, hard drives, etc. Hence, sda means that this device was detected by the computer first. * Example of **character device** is : ***/dev/consoles*** or ***/dev/ttyS0***. These devices are accessed as a stream of bytes. * Example of **block device**: /***dev/sdxn***. Block devices allow the programmer to read and write any size of the block. Pseudo devices act as device drivers without an actual device. * Examples of **pseudo devices** are ***/dev/null,*** ***/dev/zero,*** ***/dev/pf*** that's all. . . . *** sources: --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. 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