Week 1: Computer BasicsLesson 7: How Does My Computer Work?

• When you shoot a basketball, your eyes, brain, and muscles send many signals back and forth. When you use a computer, you send signals to the computers CPU (Central Processing Unit)., which is like the computer’s brain. A CPU, or microprocessor, is a small chip that performs calculations and carries out all the instructions you give to your computer. Every time you press a key on the keyboard or click the mouse, you give instructions to the CPU.

A faster CPU generally means that a computer can process more data in less time. The process of receiving and carrying out instructions is called a cycle. The speed of a CPU is measured in:

Megahertz (MHz) –millions of cycles per second Gigahertz (GHz) – billions of cycles per second

Bits, Bytes, and Binary Numbers

•Computers can process only two numbers: 1 and 0. All data a computer processes is turned into a string of 1s and 0s called binary numbers.

•A bit is the smallest unit of information, always either a 1 or a 0. Each letter, number, and symbol that we use in English is represented by eight bits. Eight bits make a byte, the building block for all information that flows through a computer. A computer file can contain thousands, millions, or even billions of bytes. A five-page research paper may use 40,000 bytes (or 40KB). A movie on a DVD holds around five billion bytes (or 5 GB).

Computer Memory and Storage BasicsComputers process a lot of data, but what do they do with it? They store it. Computers store data in three main places:

Random-access memory (RAM) Read-only memory (ROM) On a separate storage device

Types of Computer Memory

When do I use RAM and ROM?

•Both RAM and ROM work together to keep your computer running smoothly.

•When you turn the computer on and off, that is when ROM is working. ROM tells your computer how to start up and tells the operating system to start up.

•When you start and use software, you are using RAM. Once the computer starts, RAM takes over. When the operating system starts and you can see the desktop, you are using RAM. The computer will access information stored in the RAM when you start a software program like Microsoft Word.

How is information stored?

•We have all experienced that dreaded moment when we forgot to save our work and we shut down the computer. Our work is lost. This is because when you are working on something, like typing a paper in Word, the data is stored in RAM. And of course, when we shut down the computer, everything in RAM is erased.

•Therefore, it is very important to save your work, and save often. When you save a file, you move it from RAM to a storage device, such as a hard drive, a server, or a disk. A storage device is like your long-term memory, where you store important information, like your home address or memories of important events.

Types of Storage Devices

How big is a Terabyte?

• 1 Kilobyte (KB) = 1,000 bytes

• 1 Megabyte (MB) = 1,000 KB

• 1 Gigabyte (GB) = 1,000 MB

• 1 Terabyte (TB) = 1,000 GB