Chapter 1: Introduction - I

Chapter Goals

• To understand the activity of programming
• To learn about the architecture of computers
• To learn about machine languages and higher-level programming languages

What is a Computer?

• Computers can handle repetitive chores without becoming bored or exhausted.
• A computer is programmable to handle different tasks:
  • Balancing checkbooks
  • Processing words
  • Playing games
• Computer actions are composed of huge numbers of extremely primitive operations
• The computer gives the illusion of smooth interaction because it executes these operations a great speed.
• Examples:
  • Put a red dot at this screen position
  • Get a number from the location in memory
  • Send a letter A to the printer
  • Add up these two numbers
  • If this value is negative, continue the program at that instruction.
• Computers are flexible: they can handle a wide range of tasks.

What is Programming?

• A program tells the computer the sequence of steps needed to fulfill a task.
• A programmer designs and implements these programs.
• Most computer users are not computer programmers.
• Programming is an essential skill for a computer scientist.
• Programming is not the only skill required to be a successful computer scientist.
• Early programming experiences are mundane and will not rival sophisticated software that you are familiar with.
• Once certain skills are developed, even simple programs can be thrilling.

The Anatomy of a Computer

• CPU (Central Processing Unit):
  • Plastic, metal and mostly silicon.
  • Composed of several million transistors.
  • Enormously complicated wiring.
  • Performs program control, arithmetic, and data movement.
  • Locates and executes program instructions.
• Memory:
  • RAM (Random Access Memory): read-write memory.
  • ROM (Read Only Memory): contains certain programs that must always be present.
  • Secondary storage (e.g. a hard drive) provides persistent storage.
• The bus is a set of electrical lines that connect the CPU, RAM, and other devices.

• The motherboard holds the CPU, memory, and bus, as well as card slots which connect peripherals to the computer.
• Peripherals allow the user and computer to interact:
  • Printer
  • Mouse
  • Keyboard
  • Modem
• Some computers are connected to one another through networks.