How Computers Process Data

Where Processing Occurs:

• The Control Unit
• The Arithmetic Logic Unit
• Machine Cycles
• The Role of Memory in Processing 
• Types of RAM

Where Processing Occurs: 

• Processing takes place in the PC`s central processing unit(CPU).
• The system`s memory also plays a crucial role in processing data.
• Both the CPU and memory are attached to the system`s motherboard,which connects all the computers devices together,enabling them to communicate.

The Control Unit:The two main parts of a CPU are the control unit and the arithmetic logic unit(ALU).

• The control unit directs the flow of data through the CPU, and to and from other devices.
• The control unit stores the CPU`s microcode, which contains the instructions for all the tasks the CPU can perform.

The Arithmetic Logic Unit: 

• The actual manipulation of data takes place in the ALU.
• The ALU can perform arithmetic and logic operations.
• The ALU is connected to a set of resisters-small memory areas in the CPU, which hold data and program instructions while they are being processed.

Machine Cycles: 

• The CPU follows a set of steps-called cycle for each instruction it carries out.
• By using a technique called pipelining,many CPU`s can process more than one instruction at a time.
• During the instruction cycle,the CPU "fetches" a command or data from memory and "decodes" it for the CPU
• During the execution cycle,the CPU carries out the instruction, and may store the instruction`s result in memory.

The Role of Memory: 

• RAM stores data and program code needed by the CPU.The contents of RAM change rapidly and often.
• Read-only memory (ROM) is nonvolatile(or permanent).It holds instructions that run the computer when the power is first turned on.
• The CPU accesses each location in memory by using a unique number,called the memory address.

Types of RAM: 

There are two types of RAM:static and dynamic.

• Dynamic RAM (DRAM)chips must be recharged with electricity very frequently,or they will lose their contents.
• Static RAM  (SRAM) does not need to be recharged as often as DRAM, and can hold its contents longer.

Another type of RAM,called flash memory, can store its contents after power is turned off.Flash memory is used in digital cameras to store pictures.