ucs.pptxUCS UNIT 4 INPUT AND OUTPUT DEVICE

ucs.pptxUCS UNIT 4 INPUT AND OUTPUT DEVICE

• 1.
  Von-Neumann Model
• 2.
  Von-Neumann Model • Von-Neumannproposed his computer architecture design in 1945 which was later known as Von-Neumann Architecture. • It consisted of a Control Unit, Arithmetic, and Logical Memory Unit (ALU), Registers and Inputs/Outputs. • Von Neumann architecture is based on the stored-program computer concept, where instruction data and program data are stored in the same memory. • This design is still used in most computers produced today.
• 3.
  There have been2 types of Computers: • Fixed Program Computers – Their function is very specific and they couldn’t be reprogrammed, e.g. Calculators. • Stored Program Computers – These can be programmed to carry out many different tasks, applications are stored on them
• 4.
  Fixed Program Computers •They were designed to do very specific operations. • A calculator is a fixed program counter. • It can do basic mathematics, but it cannot used as a word processor or a gaming console. • Changing the program of a fixed-program machine require rewiring, restructuring, or redesigning the machine.
• 5.
  Stored Program Computers •A stored-program computer is one that stores program instructions in electronic memory. • Therefore easily reprogrammable. • Von Neumann is a stored program architecture introduced by John von Neumann.
• 7.
  Components of Von-NeumannModel: • I/O Interfaces • CPU • Memory Unit
• 8.
  I/O Interfaces • TheI/O interfaces allow the computer’s memory to receive information and send data to output devices. • Allow the computer to communicates to the user and to secondary storage devices .
• 9.
  Central Processing Unit •The part of the Computer that performs the bulk of data processing operations is called the Central Processing Unit and is referred to as the CPU. • The Central Processing Unit can also be defined as an electric circuit responsible for executing the instructions of a computer program. • The CPU performs a variety of functions type of instructions that are incorporated in the computer. • The major components of CPU are :- • Arithmetic and Logic Unit (ALU) • Control Unit (CU) • Registers.
• 10.
  Arithmetic and LogicUnit (ALU) • The Arithmetic and Logic Unit (ALU) performs the required micro- operations for executing the instructions. • In simple words, ALU allows arithmetic (add, subtract, etc.) and logic (AND, OR, NOT, etc.) operations to be carried out.
• 11.
  Control Unit • TheControl Unit of a computer system controls the operations of components like ALU, memory and input/output devices. • The execution of each instruction is determined by a sequence of control signals produced by the control unit.
• 12.
  Registers • Registers referto high-speed storage areas in the CPU. The data processed by the CPU are fetched from the registers. • Following is the list of registers that plays a crucial role in data processing.
• 13.
  Registers Description MAR (MemoryAddress Register) This register holds the memory location of the data that needs to be accessed. MDR (Memory Data Register) This register holds the data that is being transferred to or from memory. AC (Accumulator) This register holds the intermediate arithmetic and logic results. PC (Program Counter) This register contains the address of the next instruction to be executed. CIR (Current Instruction Register) This register contains the current instruction during processing.
• 15.
  Buses • Buses arethe means by which information is shared between the registers in a multiple-register configuration system. • A bus structure consists of a set of common lines, one for each bit of a register, through which binary information is transferred one at a time. • Control signals determine which register is selected by the bus during each particular register transfer. • Von-Neumann Architecture comprised of three major bus systems for data transfer.
• 16.
  Bus Description Address BusAddress Bus carries the address of data (but not the data) between the processor and the memory. Data Bus Data Bus carries data between the processor, the memory unit and the input/output devices. Control Bus Control Bus carries signals/commands from the CPU.
• 17.
  Memory Unit • Amemory unit is a collection of storage cells together with associated circuits needed to transfer information in and out of the storage. • The memory stores binary information in groups of bits called words. • The internal structure of a memory unit is specified by the number of words it contains and the number of bits in each word.