I'm not clear with the some of the concepts regarding computer such as :
The Processor line i386,i486,i586,i686 etc.What is the meaning of this ?Please somebody brief me.
1) Why term " IBM compatible PC " is used in the market? What standards IBM set for the PC ?
2) is it possible to get voltage at the USB port ? that means how USB transfers information in-terms of voltage or light(fiber optic) ? What are the contents inside the USB drive? is USB static or dynamic storage media ?
3) What is the role of RAM for the operating system?
Tried Google/Wikipedia but confused with someterms,so i thought it will be good idea to post here.Post your views
This is almost all history, so circle around boys and girls while we give you this little lesson in computer history. Now before I go explaining what I know, just be forewarned I am certainly no expert, but I have lived through this history and remember much of it from a personal perspective.
Way back when, there was this tiny company called Intel. They were known for making VLSI integrated circuits (now more commonly known as computer chips). One of the most popular chips was known simply by it's model number, the 8086 chip. This was little more than a calculator chip, but for many engineers who designed such systems based on the chip, they were able to make computers.
Back then, many different manufacturers made many different computers in many different ways. There were no standards, even between lines within the same company in many cases. Companies such as Apple Computers, Acer, Hewlett Packard, Tandy Computer Corp, and others burst on to the scene to create these machines. They were, however, completely incompatible with one another, and the hardware and software associated with the machine was custom made for that model only.
Around this time, established companies like IBM were determining how to utilize this new technology to leverage their existing systems. IBM in particular had been around for a long time custom making (mainframe) computers from whatever was most appropriate at the time - vacuum tubes, integrated circuits, wire, you name it. With the advent of the 8086 processor, IBM started making mainframes and other distributed computing systems with this cheaper technology.
Now IBM was long established within corporate America, and indeed around the world, long before computers came about. They created ticker-tape machines, typewriters, lithograph machines, etc.; so you name it, and IBM probably made it. This gave IBM a strong competitive advantage when they started selling their own version of a personal computer to bring the mainframe to the desktop (also known as the dumb terminal). However, business pressures and technology advances pushed them to selling what we would now recognize as a PC instead. With all this technology and selling power at their hands, IBM started cashing in on the very lucrative business market - really, it was the only real market at the time.
Many of the other makers were trying to break into IBM's market share as the only other market was for the hobbyist, who would not buy prebuilt machines anyway. The cost was just too high for the average person (for reference, I remember my buddy's father coming home with a low end i286 based IBM machine with a green screen that cost his company almost $6,000 in the early to mid 1980's). Therefore with IBM's dominance in business, and the makers chasing the business market, a standard arose from the dominant player. In essence, it was a might makes right situation. Everyone wanted to play with IBM, so they had to play by IBM's rules. Machines that were certified (or claimed to be certified) compatible with IBM software and machines were labeled "IBM Compatible". As this became more standard more machines acquired the title, and it became a defacto standard.
It is interesting to note that at least one company was trying to differentiate itself at the time by NOT being IBM compatible. That company was Apple Computers. After IBM more or less won the standard-setting war, most computers were seen as belonging to one of two oligarchies, Either it was an IBM Compatible, or an Apple. IBM's were just too expensive for the name brand, so the "compatible" moniker grouped all non-Apple machines. UNIX machines still existed at the time, but they were not a player on the desktop front, so it is not part of this story.
Back to Intel. From this little war between customers, Intel profited greatly. They continued to refine the 8086 chipset architecture and developed new technologies based off of it. Each new major change kept the 86 ending and it sort of became a new naming standard within Intel to define the decendants of the 8086 chipset. Each new number represented a major change (such as a version number in software). So 286 was a major change to the 8086 chip design, 386 was a major change to the 286 design, etc. Minor updates were designated by a step number. These numbers often accompanied marketing names such as MMX as f0dder mentioned. They were extension of the existing architecture in that chip family.
Frequently an x86 family change (early in its life) meant you needed completely new software. 8086 software did not run on 286 machines, 286 software did not run on 386 machines, etc. But then something happened with the 386 line. A standard was set with an upgrade path. Suddenly 386 software would generally run on 486 machines. Even today, on the newest Intel x86 processors, software made for a 386 machine will happily run - though much faster than intended, so don't 386 run games on them if you want to see what is going on
Enough of the history lesson, your other questions are best answered by others, and some of them have been quite nicely already. I have said too much already though I do think you will have to be a bit more specific about your questions on the USB. USB is a standard interface, not just a thumbdrive or a printer or other piece of hardware. When you say a USB drive, do you mean a thumbdrive or a hard drive with a USB interface? When you ask is it static or dynamic storage, what do you mean by this?