Specially designed systems (usually several computers tied together). Used primarily in government or research. These are the most expensive and largest systems available, and they possess tremendous computing power. The cost of operating and maintaining them makes them prohibitive hit most organizations. One example of a supercomputer Is 11w one operated by the National Security Agency. Built at a cost
FIGURE 9. Cray Supercomputer shown here with designer Seymour Cray of Cray Research, Inc.
Of approximately $15 million, it is rumored to be capable of 150 to 200 million calculations per second, and has a memory capable of transferring 320 million words per second. This system is reported to be so powerful that the heat is generates would melt is down were it not for a specially designed cooling system.*
At present, there are some 150 supercomputers (similar to that in Figure 9), in operation around the world, with most located in the United States. The latest models have a memory capacity some two billion bytes and processing speeds 40,000 to 50,000 times faster than a personal computer. Tasks that once took a year to accomplish on a second-generation computer can be done in about a second with a supercomputer.* Mainframes. These are the large machines that come to mind when most people think of computers. Costing hundreds of thousands of dollars, and requiring specially built facilities and large supporting staffs of operators, programmers, and analysts, they are designed to handle large volumes of work or complex calculations.
Minicomputer. Smaller than a mainframe and generally costing under $200,000, these systems are ideally suited for a medium- sized organization. They require smaller facilities and less staff than the mainframes, but have enough, power to process a wide range of commercial or scientific jobs.
Microcomputer. This is where the personal computer fits in. Designed to sit on the top of a desk, and within the financial reach of most organizations and many individuals, these systems represent the latest evolutionary stage. While not yet in the same league as their larger cousins, they can easily match or outperform the computing power of their first- and second- generation ancestors.
Lap-Top Computers. An offshoot of the personal computer, these small systems (many are complete with printer and liquid crystal displays) can offer the same type of power and functionality as a desktop model. Designed for portability, they can travel inside an attach case as seen in Figure 10, and can be used just about anywhere.
While personal computers can trace their lineage back several centuries (see Exhibit 5), they are a relatively new phenomenon. The personal computer revolution really got underway in 1969 with the invention of the Intel 4004 microprocessor, which contained 2250 transistors on a single microchip. At first, these were available only to large manufacturers, but in 1971 Intel decided to clear out its stocks by offering the 4004 microprocessor for
nice blog
ReplyDelete