CIS3355: Business Data Structures
Fall, 2008
 

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    Computers use RAM to hold the program code and data during execution. One defining characteristic of RAM is that its accesses to different memory locations are almost always completed at about the same speed, in contrast to some other technologies that required a certain delay time for a bit or byte to “come around.”

    Memory, usually referred to as Random Access Memory (RAM), is the place where an application loads its data during processing, while a hard disk drive is usually the place where data is stored for long or short term retention.In computing, RAM is random access memory.

    Random access memory or RAM is a type of computer storage whose contents can be accessed in any order. This is in contrast to sequential memory devices such as magnetic tapes, discs and drums, in which the mechanical movement of the storage medium forces the computer to access data in a fixed order. It is usually implied that RAM can be both written to and read from, in contrast to read-only memory or ROM. RAM is usually used for primary storage in computers to hold actively-used and actively-changing information, although some devices use certain types of RAM to provide long term secondary storage.

    Primary storage is a category of computer storage, often called main memory. It is used to store data that is likely to be in active use, so it is usually faster than long-term secondary storage. Secondary storage is a category of computer storage too. It is used to store data that is not in active use. It is usually slower and has higher capacity than primary storage.

How does RAM store data? 

    RAM consists of many capacitors and transistors. A capacitor and a transistor are paired together to make a memory cell. The capacitor represents one "bit" of data, the transistor is able to change the state of the capacitor to either a 0 or a 1. the Zero's and ones when read in a sequence represent the code which the computer understands. This is called binary data because there are only two states that the capacitor can be in.

    In order for a capacitor to achieve a value of 1 it needs to be filled with electrons. To achieve a value of 0 the capacitor needs to be emptied of electrons. You may of noticed when purchasing RAM that many types of RAM you buy are called DRAM or SDRAM. DRAM or Dynamic Random Access Memory has a small problem with the capacitors holding a value of 1. It is called dynamic RAM because its state of 1 or 0 needs to be constantly refreshed on order to stay in the correct state. In order to demonstrate this and for a much more detailed look into the workings of RAM a good site is How stuff works. This article will show you a much more technical look at the workings of RAM and has a great Diagram to illustrate the nature of Dynamic Random Access Memory

http://en.wikipedia.org/wiki/Random_access_memory

http://en.wikipedia.org/wiki/Datum

http://www.howstuffworks.com/ram1.htm

1. Which of the following statements is true about RAM? 

a) to hold the program code and data during execution

b) its accesses to different memory locations are almost always completed at about the same speed

c) it is a random access memory

d) A and C

e) All of the above

2.  __________is a category of computer storage, often called main memory?

a) Magnetic Tapes

b) RUM

c) USB   

d) Primary Storage

e) None of the above

3. Which of the following statements is true about a Bit?

a)  A single bit (short for binary digit) is a 0 (zero) or a 1, or a true or a false, or for that   

     matter any two mutually exclusive states.

b)  is a collection of bits

c)  hold the program code and data during execution

d)  All of the above

e)  None of the above

4. Which of the following statements is true about a Byte?

a)  is a collection of bits

b)  is a category of computer storage, often called main memory

c)  It is used to store data that is likely to be in active use

d)  All of the above

e)  None of the above

5. How do we know where a piece of datum is stored in RAM?

a) We don't know

b)  We don't know

c) We don't know

d) We don't know

e) We don't know

1. E

2. D

3.A

4.A

                      5. We don't know