People wrote letters to their friends on paper, and licked the envelopes and stamps.

Today all these functions have been replaced by processes that represent the music, pictures, text, library catalogue entries and just about every other kind of information you can think of as numbers. These numbers are manipulated by computers that compress, encrypt, slice, chop and mix the information they represent, and exchange this information with other computers, often located at great distances.

What do computers, which run on electricity and manipulate numbers, have to do with photography, or music? How does a song on a iPod manage to take up a smaller number of megabytes than the same song on a CD? (And while we're on the subject, what's a megabyte? ) How does the global Internet, which has become such a dominant presence in our lives, move information around? How is this information kept secure, so that when you type your credit-card number to buy something from a Web retailer, it cannot be read by people who want to steal your money? How is the information indexed so that you can find it quickly on a search engine like Google?

This course has been designed to teach you how this stuff works . Although you will be using a computer all the time in your work in CS074, it is not a how-to course on useful computer applications, but more a look under the hood at the technical underpinnings of the subject, as well as its historical roots and social impact.

Another way to say it is that this course is an introductory survey of Computer Science, whose subject matter is the representation and manipulation of information.

There are three distinct parts to the course.

Part I will examine how computers represent information. Everything in the digital world--text, numbers, audio, still photos, video--is represented as sequences of bits. You will use a software tool that will let you experiment with digital processing of text, audio and images, and learn about methods of data compression.

Part II is devoted to the applications of computers and computing. While you study a number of different topics (cryptography and security, the Internet, machine intelligence), you will also learn the rudiments of computer programming, so that you can begin to get an idea of what goes into the development of such applications.

Part III is devoted to computer hardware and how computers themselves work. You will experiment with building simple digital circuits and play with a very simple processor.