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4. Inside a Computer – Hardware and Software – How it works Aim: In this lesson, you will learn: The main hardware and software components of a computer. Functions of different computer parts. Jyoti: Computers are made of electronic parts called components. Each component has a specific function. They all work together when a computer is operated. Some of the components can be seen partly from the outside. Some components are hidden inside the computer where we can’t see them. Tejas: Finding information about the components inside a computer was very interesting. Look at the brain of the computer. Whenever we press a key, click the mouse, or start an application, we send instructions to the CPU. These are all executed by the CPU. Jyoti: Can we see the details of the components inside this computer? Moz: Yes. Click on the system submenu. System monitor shows you details and status of hardware and software of the computer . Jyoti: Hey! There are two processors in this computer. There are many details for the processors. Moz: The processing of your instructions is shared between the two processors, just the way you share work among your team. Jyoti: What does 2.10 GHz mean? Moz: This stands for 2.10 Giga Hertz. You know that Mega means million and Giga means billions. Hertz means cycles per second. CPU needs one or more cycles to perform an action. More cycles per seconds means more instructions can be processed per second. So, the higher the Hertz, the faster the computer can process instructions. 12 Processor (CPU) The Central Processing Unit (CPU), also called a processor, is the brain of the computer. It executes instructions in response to commands. Concept Processor (CPU) Central Processor speed is measured in Hz. A processor’s Proceesing speed is measured in megahertz (MHZ), or Unit gigahertz (GHZ), So, the higher the hertz, the (CPU) Info faster the computer can process instructions. The CPU is generally a 2 inch ceramic square with a silicon chip located inside. The chip usually about Executes program the size of a thumbnail. commands Tejas: Main memory is used to store programs and data when CPU is processing. Moz: The computer’s work takes pla1ce in RAM. This is where programs run when you are using Word processor application to create a document, or Scratch to create an animation. Jyoti: What does 2.8 GB mean? Moz: Let us first understand how computers store information. Computers store information digitally. All the information is broken down into pieces and stored as numbers. These are converted to a binary system. Main Memory RAM (Random Access Memory) is also called main memory. RAM is used to store data and instructions that are currently being processed by a computer’s CPU. Data is temporarily stored here until the work Concept is saved to the hard disk. The data in RAM is erased on power off of computer. Main Memory Central Executes RAM is measured in megabytes (MB) or gigabytes Proceesing program (GB). A bit is the smallest unit of data in computer Unit commands processing. A byte is a group of eight bits. A (CPU) Kilobyte (KB) is 2^10 bytes or approximately 1024 Info bytes. A Megabyte (MB) is about one million bytes. A gigabyte (GB) is 1,024 megabytes. The more RAM a computer has, the more things a computer Primary storage can do at the same time, and the faster a computer Main performs tasks. memory area for programs and data that are in active use 13 Jyoti: The content that we save in a computer is written into secondary storage. Tejas: Whatever we save on a hard disk can be retrieved later. It is like a permanent storage device. Moz: The hard disk stores multiple type of data and applications. The documents and content that a user creates and saves, the software to operate the computer and the applications like Word processor, Scratch etc. are stored on the hard disk. The computer loads the instructions from long-term storage (your hard disk) into main memory as and when required. Jyoti: The amount of data, programs that we can store on a hard disk depends on its size which is measured in giga bytes. Tejas: We can also record data to CD/DVD or pen drive. The memory of these devices is not as much as a hard disk drive. Moz: Correct. These devices are called removable storage devices, which can be removed from the computer and connected whenever required and carried. The hard disk is also sometimes removable. Jyoti: A few days back I created a greeting on the computer. I saved it on hard disk and also copied on to the pen drive. Next day the computer did not work. But since I had a copy on the pen drive I could copy it on to another computer and mail it to my friends. Moz: Making another copy of a document or information that you create on the computer is called taking backup. Backup of content (documents, paintings, reports etc.,) that you create is important. Backup can be taken on CD/DVD, pendrive, or a removable hard disk, or another computer where you have access. Tejas: We can also mail a copy to ourselves if we have internet connectivity. Moz: Right. This is good option when you have internet connectivity. Backup Backup of data and information that you create is important. Many backup options are available, like mailing a copy of the content to yourself, taking a backup on pen drive, a CD/DVD, another computer. This ensures that even Concept if one device fails you have a copy of the content (documents, paintings, projects etc that is created using a computer. Jyoti: We also get books, games, educational lessons on CD/DVDs. Moz: Correct. These devices can also be used for distribution and sharing of resources. 14 Secondary Storage Secondary storage is where the information is stored permanently till explicitly deleted. Information is moved between main memory and secondary memory as and when needed. Concept On power off of a computer, data on hard disk and other secondary storage devices is not erased. Secondary Storage Information is Central moved between The hard disk drive is the data center of the computer. Proceesing main memory Operating system, software, content created and Unit and secondary saved by users are stored here. The hard disk drive (CPU) memory as is long-term storage where information is stored needed. permanently until explicitly deleted by user. This is Info usually found inside a computer. CD/DVD and pen drive are removable storage Main Hard disk devices. These can be used to backup important CD/DVD data and information. It is also sometimes used to memory Pendrive distribute or share information, books, software, games, etc., Jyoti: We already know what are input and output devices. Examples of input are keyboard, digital camera, and mouse. Printer, Monitor is examples of output devices. Tejas: This is how input to output happens in a computer. For example the following fig. Shows how the monitor displays an “A” that is typed on the keyboard. 1 0 0 0 0 0 1 0 Central Proceesing A Unit (CPU) Monitor Electrical signal A Keyboard Moz: Correct. User interacts with the computer using these devices, also called peripheral devices. The electrical signals for example the alphabets typed on a keyboard, are converted to binary code. When the computer displays the data on a monitor or when output is a printout, the binary code is again converted to the human understandable characters. 15 Input/output (I/O) devices An input device converts data and instructions entered using the device into a pattern of electrical signals in binary code that can be processed by a digital computer. A user inputs data and instructions (example: using a keyboard), initiates a task (Example: using a mouse), transfers images (example: using a web camera), using the input Concept devices. An output device reverses the process, translating the digitized signals into a form intelligible to the user. The computer displays processed information (example: a print out of the information or audio, video) through the output devices. User interactions are facilitated through I/O devices Input/output (I/O) devices Monitor Central Keyboard, mouse, scanner, webcam are Keyboard examples of input devices. Proceesing Unit Monitor, printer, speakers are examples of Mouse Info output devices. (CPU) Some devices can handle both input and output. Network Network is one such example. Network device called network card in a Hard disk computer is both input and output device. Main CD/DVD memory Pendrive Gurpreet: At the back of the computer we find many sockets which are called connection ports to connect the external devices like keyboard, mouse, speakers, power, monitor etc. Jyoti: Port is of different shape and Connection Ports size. Some of them are network port, USB port, etc. Function of a port: Moz: The ports look different since A port is an interface between the computer and they carry different amounts of other computers or peripheral devices. It provides a signal transfer between devices. A port is connected information. The colour code and from inside to expansion cards which are plugged look also helps to quickly identify Concept into the motherboard and are connected to other the correct port while connecting components by cables which are long, flat bands peripherals. that contain electrical wiring. The ports are controlled through the expansion cards. 16 Connection Ports At the back of a desktop computer various connection ports are available to connect the external devices and power. On a laptop these are available on the left and right side edges.

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