Friday, February 25, 2005

Programs

Computer programs are simply large lists of instructions for the computer to execute, perhaps with tables of data. Many computer programs contain millions of instructions, and many of those instructions are executed repeatedly. A typical modern PC(in the year 2003) can execute around 2-3 billion instructions per second. Computers do not gain their extraordinary capabilities through the ability to execute complex instructions. Rather, they do millions of simple instructions arranged by people known as "programmers." Good programmers develop sets of instructions to do common tasks (for instance, draw a dot on screen) and then make those sets of instructions available to other programmers.
Nowadays, most computers appear to execute several programs at the same time. This is usually referred to as multitasking. In reality, the CPU executes instructions from one program, then after a short period of time, it switches to a second program and executes some of its instructions. This small interval of time is often referred to as a time slice. This creates the illusion of multiple programs being executed simultaneously by sharing the CPU's time between the programs. This is similar to how a movie is simply a rapid succession of still frames. The operating system is the program that usually controls this time sharing.

2 comments:

Quit Smoking said...

Hello fellow fisherman,

Did you know that 16% of the U.S. population goes fishing at least 16 days a year?

Did you also know that over 75% of the nations fishermen do not fish during "prime time"; fish feeding hours?

Those precious few moments before twilight can be absolutely magical. Even up until 11pm at night, the largest predators of any species feed ravenously.

Don't believe me? Check out Daniel Eggertsen's story, and a picture of a couple of his catches here : "Evening Secrets plus more"

I want you to do me a favor and try it out so I can see what you think of it, and if it works for you as well as it did for me.

You will be one of the first to try it out.

Gone Fishin',

Neil

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