## 1.1: Anatomy of a computer ### 1.1.1: Hardware #### Introduction Hardware : the physical pieces of a computing machine In this section, we will look at the different physical components of a computer. They will be described in general, for any type of computing device. However, the images will all be related to how the hardware looks inside a desktop computer. For smaller devices, such as laptops, tablets, smartphones, smartwatches, smart refrigerators, smart doorbells, etc, most of the same components will be necessary, but they will be much more compact and harder to differentiate between the components.

Exterior of a desktop computer

desktop computer interior — What it looks like when you remove the side of the case

#### Components Overview Essential hardware for our typical modern computing devices (desktops, laptops, tablets, smartphones): * The **motherboard** is the electrical component that enables data and power flow between multiple components. Everything connects to the motherboard in one way or another.

desktop computer interior, before components have been added — This is the same desktop computer as shown above, but before any additional components were connected. So, all you can see is the motherboard, the case itself, and some cables.

* The **CPU (Central Processing Unit)** is the processor that does all the "work" and computations for the device.

CPU, pin side up — This is a real desktop/server CPU, showing the pins that plug in to the motherboard.

CPU, pin side down — On the other side of the CPU, you would glue a "heat sink," which is a fan meant to keep the hardworking CPU from overheating and frying its electrical components. You can see the leftover glue on this CPU because I didn't clean it.

* The **RAM (Random Access Memory)**, or often referred to as **main memory** or just **memory**, is where data is stored while it is in use by the device. RAM is *volatile* storage, meaning that its contents are emptied or lost when the device is powered off.

One stick of RAM — A RAM stick that would be plugged directly into the motherboard.

* The **cache** is data storage contained on the processor. It is directly accessible by the processor and is the fastest possible form of data storage. However, because it is on the processor it is very small and limited in the amount of data that can be stored. Cache, like main memory, is volatile storage. * An **HDD (Hard Disk Drive)** or **SSD (Solid State Drive)** serves as the device's non-volatile storage. It is the slowest form of storage discussed here, but it can store large amounts of data and is not emptied when the device loses power. HDDs are older forms of storage which are made of literal circular disks. SSDs allow faster access (for data storage or retrieval) than HDDs and use electrical circuits and flash memory to store data rather than physical disks.

Interior of HDD showing physical disks — This is an HDD with the top cover removed. You can see the physical disks stacked inside the drive.

Interior of SSD showing flash memory blocks — This is an SSD with the top cover removed. You can see the flash memory blocks and other circuitry.

* In lieu of HDD/SSD, we typically refer to the non-volatile storage in smaller devices like tablets and smartphones (as well as USB storage drives, aka "thumb drives" or "flash drives") as **flash memory**. This type of storage is electrical like SSD storage, but is usually built into the device rather than being connected as a separate removable/replaceable drive.

Interior of USB drive — This is a USB drive with the top cover removed. You can see the flash memory blocks and other circuitry.

#### Peripherals Peripherals are also considered hardware. These are devices that are separate from the main computing device but plug in to it to allow for additional functionality, often related user I/O. I/O : stands for Input/Output Common examples of peripherals: * monitors * touchscreens * keyboards (physical keyboards are peripheral devices; on-screen keyboards for touch devices are purely software that uses the screen for I/O)

Photo of four mechanical keyboards of different sizes and designs — These are all custom built or modified mechanical keyboards.

* audio devices (headphones, speakers, microphones) * cameras * mouse * writing and drawing tablets (like Wacom tablets)

Back of a desktop tower, showing all exterior ports — The block of ports on the top left are directly on the motherboard. The two rows of ports in the middle of the case below that are on the video card, which is plugged in to the motherboard.

#### Summary The image from the beginning of this section has been included again below, but now with labels to help you locate all the hardware pieces you just learned about.

The inside of a desktop computer, with important hardware components labelled.

*** All images on this page belong to Angela Berardinelli, except HDD image (source: PCWorld.co.uk) and SSD image (source: tomshardware.com) and USB drive image (source: stock photo from alamy.com)