h readers (especially recent college gradu- ates) will be able to properly understand the macroscopic picture of how and why we arrived where we are. This background will enable readers to better view these complementary technologies in rela- tion to each other and to appreciate and understand the main network-processing technologies dis- cussed in this book. IN THE BEGINNING An explosion of information technology (IT) occurred predominantly in the last quarter of the twen- tieth century. Computers, which were exotic devices to previous generations, have by now become indispensable tools for our everyday work and leisure. Today all branches of industry, processes of workflow, channels and methods of education, manufacturing techniques, financial management tools, audio and video entertainment systems, transportation systems, electronics and engine control systems, and even humble video games have taken advantage of this unbelievable progress. In the 1960s and early 1970s, when many of us were in college, working with a computer meant standing in line to use card punchers to write programs in primitive languages. A student program- mer would have to wait until the following day to receive the printout results because the data-center staff had to feed numerous programs on a batch base daily into the university mainframe. The spooler was invented to manage the output for SO many different people at different times of the day. This pro- duced one single output point that would convey the results to the users who were expecting to see the fruit of their work. This all sounds unreal, yet it was still happening just 25 years ago. Large mainframe computers were the solution for that era's IT problems. IBM was the leading par- adigm for these computers. Companies that more or less emulated its business model, such as Amdahl, Burroughs, Control Data, and SO on, also dominated the stage. Only universities, major organizations, Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copy