Encoding of Information

-
  • In computers, encoding is the process of putting a sequence of characters (letters, numbers, punctuation, and certain symbols) into a specialized format for efficient transmission or storage.
  • Decoding is the opposite process -- the conversion of an encoded format back into the original sequence of characters.
  • Encoding and decoding are used in data communications, networking, and storage.
  • The code used by most computers for text files is known as ASCII (American Standard Code for Information Interchange).
  • ASCII can depict uppercase and lowercase alphabetic characters, numerals, punctuation marks, and common symbols.
  • Other commonly-used codes include Unicode, BinHex and Uuencode.
  • In data communications, Manchester encoding is a special form of encoding in which the binary digits (bits) represent the transitions between high and low logic states.

Operation Code (Opcode)


  • It specifies the operation to be performed.
  • The operation of the CPU is determined by the instructions it executes.
  • The instructions are referred to as machine instructions or computer instructions.
  • Each instruction must contain the information required by the CPU for execution.

Encoding and decoding

  • It is important that the opcode word be easy to decode.
  • A decoder that must examine a large number of opcode bits simultaneously requires a correspondingly large number of levels of logic gates and introduces a large delay.
  • If the opcode is divided into small fields and a separate decoder is used for each field, the decoding delay will be much smaller.
  • Three formats are used for data manipulation instructions and the fourth is used in flow control instructions such as branch and branch-to-subroutine.
  • The opcode field also determines certain units which will be responsible for completing the execution of the instruction and so should read the information on the source buses.

Comments

Post a Comment

Popular posts from this blog

ONE DIMENSIONAL RANDOM VARIABLES: Handwritten notes

-
Properties of probability Distribution Function Expectation Value For the following problem by using Find the distribution function of x? What is the smallest value of x? for which probability P(X<=x)>0.5 for more click here ---------------------------------------------------------------------------------------------------------------- Continues Random Variable           We call the distribution function as probability density function f(x). Properties of probability density function.  click here ---------------------------------------------------------------------------------------------------------------- Moment Generating Function (MGF) Properties Additional property in MGF  for notes click here ---------------------------------------------------------------------------------------------------------------- Bernoulli Trial       For a single trail with only two possible res...
Read more

Design and Management of Computer Networks Running Notes

-
Architecture and Design Process Hierarchy and Inter-connectivity Network Supportability ------------------------------------------------------------------------------------------- Service Description pdf Service characteristics pdf Service Levels pdf System Components and network services pdf Service Requests and Requirements pdf Service Offerings pdf Service Matrices pdf Performance Characteristics pdf for running notes Download here ------------------------------------------------------------------------------------------- Types of user requirements pdf Timeliness Interactivity Reliability Presentation Quality Adaptability Security Affordability Functionality Supportability Future growth Requirement Analysis pdf The need for Requirement Analysis User Requirements pdf for running notes Download here -------------------------------------------------------------------------------------------  Ap...
Read more

Microprogrammed Control Unit for the Simple Computer

-
Image
In the case of a hard-wired control unit the control matrix is responsible for sending out the required sequence of signals.  Each bit of a microinstruction might correspond to one control signal.  If the bit is set it means that the control signal will be active; if cleared the signal will be inactive.  Sequences of microinstructions could be stored in an internal "control" memory.  Execution of a machine language instruction could then be caused by fetching the proper sequence of microinstructions from the control memory and sending them out to the data path section of the computer.  A sequence of microinstructions that implements an instruction on the external computer is known as a micro-routine.  The heart of the controller is the control 32 X 24 ROM memory in which upt to 32 24-bit long microinstructions can be stored.  Addresses provided to the control ROM come from a micro-counter register  The micro-counter, in turn, receiv...
Read more