比较题

1.SRAM and DRAM

*RAM is short for random access memory.

@Static RAM(SRAM) keeps data in the main memory,without frequent refreshing,for as long as power is supplied to the cicuit. SRAM is very fast but it is much more expensive than DRAM and takes more space than DRAM.

Dynamic RAM(DRAM) is the most often used RAM in today's computer.DRAM can hold its data if it is refreshed by special logic called the refresh circuit.It is much cheaper and take much less space than DRAM.

2.System software and Application software

*What is software?

Collection of programs is called software .

*What is computer softwar?

It is defined as the instructions and associated data , stored in electronic format , that direct the computer to accomplish task.

*what is the shareware ?

Shareware is copyrighted software marketed under a “try before you buy” policy.

@Systemsoftware is the stuff that make your computer work.The application software is generally the computer programs which are used for the purpose of performing special tasks using a computer,it trains the PC s brain for higher cognitive functions rather than just keeping the PC alive and connected to the other.

*Examples about Application Software:(1)Accounting software(2)Collaboratire software(3)Compilers and Interpreters(4)Computers Games(5)Database(6)Educational software(7)E-mail

http://doc.xuehai.netN and WAN

LAN:A LAN is a high-speed data network that covers a relatively small geographic area .It typically connects workstations, personal computer, printers, servers, and other devices.

WAN:A WAN connect multiple geopgraphically nearby LANs to one another over great geographic distances. The speed available on a WAN waries depending on the cost of the connections and may be low. WANs opeate using routers , which can “choose ” the most appropriate path for data to take to reach a network node.

4.What's the difference between Software Engneering & System Engneering ? @System Engineernig is concerned with all aspects of computer based systems development

including hardware ,software and process engineering.Software Engineering is part of this more general process.