Processing

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					                                Processing

It refers to the manipulation of data by editing and updating. Different application
programs process different data type.


Non- computer tools for processing.

   1. Documentation: writing down the procedure used to process data or how
      calculations are carried.

   2. Data flow diagrams (DFD’s): a graphical method of representing a system and
      it’s input, processing and output. The DFD’s show the flow of data between
      processes in a system.

   3. System flow chart shows both the flow of the data and the logic of the
      system.



Hardware
Processing is carried out by the computer’s Central Processing Unit (CPU). The speed
of processing is measured by the clock speed. The speed of the clock determines how
many cycles of processing can be done in a second.
Processing is also dependent on the memory of the system.

Central Processing Unit

The CPU is regarded as the “brain” of the computer. The CPU accepts the data from
                      an input device, changes this data according to the
                      instructions given by the user and sends the results to an
                      output device. The CPU consists of millions of electrical
                      components located on a silicon chip. There are many different
                      types of chips like: Motorola and Intel, Cyrix.

                         When a CPU is contained on a single integrated circuit, it is
                         called a microprocessor. The integrated circuits are located
on a flat printed circuit board inside the computer called the motherboard. Software
and Hardware manufacturers work together to several industry standards to make
the same programs run on different computers.


CPU Components

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The CPU consists of three components:
1. Control Unit: directs and controls the entire computer system. It directs the
    flow of data within the computer system. It selects and retrieves the instructions
    from storage in sequence, interprets them and sends to the arithmetic logic unit
    for required operation.


2. Arithmetic Logic Unit (ALU )
    This is the part of the CPU that performs the arithmetical and logical
    calculations.
    Arithmetical calculations involve addition, subtraction, multiplication and division.
    Logical calculations have a true or false answer and include relational operators
    such as: <, >, =, <=, >= <>



3. Register a temporary storage area for small amounts of data and instructions
   used for and keeping the results of processing. These are additional areas in the
   CPU. The registers assist the CPU by giving it greater processing speed by
   transfer of data and operators from the RAM.

The Processing Cycle



                       Basic Machine Cycle




       DECODE                                 EXECUTE
   Control unit                                alu


Instruction time            execution time




                   FETCH    STORE
                            memory




This is also called Fetch-Execute Cycle. The processing of data is done in machine
cycles. One machine cycle represents a single instruction carried out by the CPU.

The Fetch-execute cycle consists of the following steps:

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1. Fetch: The control unit fetches(gets) the instruction and data address from the
   memory(RAM).
2. Decode: The control unit decodes the instructions (works out what to do) and
   makes the data available to the ALU.
3. Execute: The arithmetic logic unit performs the required operations on the data.
4. Store: the control unit places the results of processing into the memory or the
   registers.
 Steps 1 and 2 are termed as instruction time.
 Steps 3 and 4 are termed as execution time.

Pipelining: in pipelining the CPU fetches a new instructions as soon as the previous
instruction moves to the next stage. This feature speeds the fetch-execute cycle.



Processing Speed
All computers have an electric clock to regulate the fetch-execute cycle. The clock
speed is based on the number of electrical pulses per second and is measured in
Megahertz (mHz). The higher the clock speed the faster the CPU can work.
Apart from the clock speed the system’s performance is measured using:
   Word size - refers to the number of bits processed by the CPU at once. It can
    be 8, 16, 32, or 64 bits.
   Response time - the time taken for a computer to respond to a command. The
    time varies with the type of data entered or the command issued. Usually it is less
    than one second.

   CPU utilisation - the amount of time the CPU is actually working and not waiting
    to recieve data from disks.


Memory
This is the part of the computer that holds data and programs before and after been
processed by the CPU.
Memory consists of: RAM, ROM, and Cache.


RAM
This is the temporary storage area where the data and instruction are held. RAM is
volatile- when power is turned off, the contents of memory are lost. The data in the
RAM is accessed randomly, meaning that only one byte of memory is accessed without
affecting any other bytes.

There are two types of RAM:


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              Dynamic RAM (DRAM). RAM the memory is constantly refreshed. Must
               be updated a thousand times a second as the capacitors used to store the
               data quickly lose their electrical charges.
               SDRAM is known as synchronous DRAM. It is synchronised with the CPU
               so its faster than the DRAM.

              Static RAM (SRAM) This type of RAM does not need to be refreshed.
               They have a faster access time and are mainly used in portable computers
               and the cache.


Cache
Pronounced as“cash” it is a temporary storage area for frequently used data and
instructions. The larger the cache, the faster the computer will operate. There are
two types of caching:
             Cache memory – a high-speed memory located in between the CPU and RAM.
             Disk cache – works in a similar way as the cache memory. It stores the most
              recent data from the hard disk in RAM. When the CPU needs to access data
              from disk, it checks the disk cache.


ROM
ROM holds instructions that are fixed during production. The instructions stored on
the ROM are called firmware. ROM stores important programs such as: booting and
checking for input and output devices. ROM is non-volatile.


Types of Processing
There are three types of processing used with networks:

1. Centralised processing is controlled by a central computer such as mainframe. It
   allows data and resources to be shared.



2. Distributed processing consists of workstations connected to shared data and
   resources. It will function even if some workstations are down

3. Parallel Processing uses multiple processors. They are much faster.


Software and processing different data types:

Text and Numbers – are processed in by doing the following: deleting, moving,
copying, spell-checking, using for calculation as in spreadsheet, replacing as in
databases.

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Images – are edited by using graphical tools. Images can be cropped, positioned,
resized, and distorted.

Video and audio – edited using digital video production software. editing involves
adding text, audio, and graphics to the video clip. Sounds are edited by deleting
sounds, changing speed, adding effects, overlaying sound files (mixing).




Complete the table below.
Data Types     Software                             File Extensions
Text and
Numbers

Images



Video



Audio



Animation




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