Introduction to Computers: Hardware

What’s inside the box?

Whether we are talking about a Windows or Macintosh computer, laptop, tablet, smartphone, or video game system, the basic hardware in the computing device is essentially the same.

Personal Computer (PC) hardware consists of the component devices that are the building blocks of the machine. These are typically installed into a computer case, or attached to it by a cable.

Hardware refers to the physical parts of the computer itself, including processor, motherboard, power supply, memory, drives, case and peripherals.


Processors are the brains of the operation, and include the Central Processing Unit (CPU) and Graphics Processing Unit (GPU) for video.  The term CPU relates to a specific chip that is mounted to the main board (motherboard) in the computer.  Currently the Pentium chip or processor, made by Intel, is the most common CPU in both Windows and Macintosh computers.  However, there are many other companies that produce processors for computing devices, such as AMD, Texas Instruments and Motorola. Current Intel processor naming convention is in the format i3, i5, i7, with higher numbers being faster.

Processors are measured by the speed that they perform calculations (clock speed). Some of the first home computers operated at approximately 30 megahertz (MHz – million cycles per second), and modern home computer processor speeds have increased more than 100 times.   Over the last few years, maximum speeds have plateaued and manufacturers are focusing on including more than one processor in a single chip (dual, triple, quad, etc.) and on smaller processors that consume less power for maximizing battery life in portable devices.

Trav’s Tips:  Apple Macintosh computers used a different processor and hardware format from Windows computers until 2006.  This meant that they were fundamentally incompatible and basically did not ‘play nice together’.  After 2006, Apple changed to use Intel processors and hardware, and now it is possible to install and run Windows on an Apple computer.   Current Windows and Apple computers are virtually identical in how they work inside and share many of the same hardware components.  


Memory comes in two basic formats:  storage and RAM (Random Access Memory).  Storage memory is typically many times larger than RAM memory and storage data remains saved even when the device is powered off.  RAM is temporary memory managed by the device (not the user) and it does not save data.

A hard disk drive (HDD) is a data storage device used for storing and retrieving digital information using rapidly rotating discs (platters) coated with magnetic material. An HDD retains its data even when powered off.  The two most common form factors for modern HDDs are 3.5-inch in desktop computers and 2.5-inch in laptops. HDDs are connected to systems by standard interface cables such as SATA (Serial ATA) internally or USB (externally).  We will discuss USB in more depth.

As of 2012, the primary competing technology for storage memory is in the form of solid-state drives (SSDs). Solid state drives are replacing rotating hard drives especially in portable electronics where speed, physical size, and durability are more important considerations than price and capacity.

Trav’s Tips: Imagine a computer as a house.  The person living and working in the house is the CPU.  That person moves at a maximum speed to get tasks done.  It is possible to replace that person (CPU) with a younger and faster model, and there is a maximum speed that they can complete work.  A multiple core CPU is analogous to several identical people living and working in the house.

The hard drive is the main storage area in the house and is located in the basement.  It is a large area where the person can permanently store items (files, pictures, movies, etc).  However it takes the person (CPU) a certain amount of time to go downstairs and access the items in the basement (hard drive).  The only time items are saved in storage, or retrieved from storage is when the person decides to do it – it is not automatic.

RAM is different type of memory from storage.  RAM is a small magic shelf that is in the same room as the person works.  The RAM is able to guess what the next item the person will need, and this item is immediately placed within reach on the shelf.  It is very quick for the person (CPU) to retrieve the item from the shelf (RAM) – much faster than going downstairs to retrieve it from storage in the basement (hard drive).  The items that go on the shelf constantly change depending on the task the person is doing.  However, the shelf is limited in size, and items that appear on the shelf are simply best guesses; sometimes wrong guesses that require a slower trip to retrieve the needed item from storage.  Buying a bigger shelf (increasing the amount of RAM) allows for more guesses (with greater likelihood of getting it right) and can significantly increase the apparent speed of the computer. 

Orders of Magnitude and Memory

  • Bit                           Simply an on or an off signal.
  • Byte                        The basic unit of storage.  8 Bits.
  • Kilobyte (Kb)            1000 bytes.  (In truth it is 1024 bytes – rounded for simplicity)
  • Megabyte (Mb)        1,000,000 bytes – a million bytes.
  • Gigabyte (Gb)          1,000,000,000 bytes – a billion bytes.
  • Terabyte (Tb)           1,000,000,000,000 bytes – a trillion bytes. 

How large are common files?

  • 1 byte              A single character (letter, number or symbol).
  • 1 kB                Half a page of unformatted text, a text message or a very short email.
  • 30 kB              A 5-page word-processor document.
  • 500 kB            A PDF (Adobe Portable Document Format) document;
  • 1.4 MB            The amount of data on a floppy disc.
  • 5 MB               A three-minute MP3 audio (song) at a very high quality or 1 minute of low-resolution video or the complete works of Shakespeare (uncompressed).
  • 10 MB             Maximum size of an email that you can expect all recipients to receive.
  • 25 MB             The approximate size of the 26-volume 1911 edition of Encyclopedia Britannica.
  • 700 MB          Maximum amount of data on one CD disc or 80 minutes of uncompressed audio.
  • 1.5 GB           A high definition movie file stored in a common format.
  • 2 GB – 10 GB  The typical amount of RAM found in a modern computer.
  • 4.7 GB           The maximum amount of data on a DVD disc (single layer).
  • 25 GB            The maximum amount of data on a Blu-ray disc (single layer).
  • 100 GB          Typical hard drive size on a computer as of 2008.
  • 500 GB – 1 TB  Typical hard drive size on a modern computer.
  • 3 TB               Largest commonly available hard drive as of 2012.

All drives are memory storage devices.  They can be magnetic discs: hard (HDD) or floppy (FDD), solid state (SSD), flash (thumb or USB) or optical disc: CD, DVD, Blu-ray, etc.

Trav’s Tips:  Recordable CD, DVD and Blu-ray discs are all physically the same:  a 4.7” plastic optical disc designed to store digital data (files, documents, music, movies, etc).  They may look the same, but they store vastly different amounts of information and require specific readers (drives) to access that information.


Other extra add-on hardware parts are called peripheral components (or devices) and include the keyboard, mouse, monitor, printer, modem, scanner, camera and add-in cards (sound, video) etc.


In computer hardware, a port serves as an interface between the computer and other computers or peripheral devices. Physically, a port is a specialized outlet to which a plug or cable connects to provide a signal transfer between devices.

Common ports found on home computers include:  audio (analog and digital), video (VGA, DVI, HDMI), Ethernet (internet LAN – Local Area Network), PS/2 (keyboard and mouse), and USB.

Universal Serial Bus (USB) is an industry standard developed in the mid-1990s that defines the cables and connectors for connection, communication and power supply between computers and electronic devices.  USB was designed to standardize the connection of computer peripherals (including keyboards, pointing devices, digital cameras, printers, portable media players, disk drives and network adapters) to personal computers, both to communicate and to supply electric power.

It has become commonplace on other devices, such as smartphones and video game consoles. USB has effectively replaced a variety of earlier interfaces, such as serial and parallel ports, as well as separate power chargers for portable devices.  There are several different shapes of USB cables and ports (standard, mini and micro) and different revisions and specifications (USB 1, 2 and 3).

In computing, a plug and play device is one that facilitates the discovery and set up of a hardware component automatically upon connection.  USB is the most common plug and play connection.

Hardware Learning Check

  1. T or F              Intel makes the majority of the processors for both Windows and Apple computers.
  2. T or F              Processor speed is measured in megabytes.
  3. T or F              A new peripheral made for an Apple computer will probably not work on a Windows computer.
  4. T or F             If my computer is running slowly, buying more RAM will likely help speed it up.
  5. T or F              I can save a music cd as a data file and email it to friends
  6. T or F              I can attach a keyboard to my computer using the HDMI port.
  7. T or F              I can’t save music on a DVD disc because it is only used for movies.
  8. T or F              The USB port can charge the batteries of many portable devices because it transfers both data and power.
  9. T or F              A 1 Tb hard drive should be able to store approximately 1 trillion characters, or over 1000 CD’s, or about 200 DVD’s.
  10. T or F              I can save documents in RAM on my computer to access later.

How Computers Work

Computers basically function by:

  • Accepting input
  • Processing that input information
  • Producing output

Input: Information and programs are entered into the computer through input devices such as the keyboard, disks, or through other computers via network or Internet connections.

Output: Output devices display information on the screen (monitor) or print to a printer and can send information to other computers. They also display messages about what errors may have occurred and provide message or dialog boxes asking for more information to be input.

Processing: The CPU directs the operation of the input and output devices. The memory or RAM temporarily stores information (files and programs) while you are using or working on them. The basic input/output system controls the dialogue between the various devices.