The central processing unit by group 5 2015

GROUP 5PRESENTATION

Kufa Tendai Portia Maramba Bigboy Nyazwigo Michelle Manyeku Valerie Nhachi Makandanje Farai Samuel Makota Taranganayi Blessing Kapingura Partmore Karuma Tendai Taruvinga Joseph

CPU..

Brief history….

PRESENTER>>>VALERIE NHACHI

HISTORY..

Continued…

The Motherboa

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TENDAI KUFA

• The motherboard serves as a single platform to connect all the parts of a computer together.

• It can be considered as the backbone of a computer.

• Some of the popular manufactures are: ASUS, Intel, Aopen, ABIT, Biostar, Gigabyte and MSI

CONTROL UNIT

PRESENTER…PORTIA MARAMBA

CONTROL UNIT• DEFN This is a portion of a computer that coordinates

the operation of all the computer’s devices, prescribing specific actions according to a given program.

It directs traffic (it represents the flow of info) eg camera, traffic lights

Functions • The control unit generates control

• It manages and coordinates all the units of the computer.

• It is responsible for controlling the transfer of data and instructions among other units of a computer.

• It communicates with Input/Output devices for transfer of data or results from storage.

• It does not carry out data processing or storage

HOW IT WORKS• It obtains the instructions from

the memory, interprets them, and directs the operation of the computer

• - This part of the of the CPU is the one that is in charge of all the operations being carried out.

• - It helps in communication between the memory and the arithmetic logical unit.

• - It also aids in the loading of data and instructions residing in the secondary memory to the main memory as required.

IT COMPRISES OF 3 main elements of that are the decoder , timer/ clock

and the control logic circuits

Decoder

Timer

Control logic circuits

TYPES OF C.UHardwired Hard-wire control units were the

first type of control units. (wires)

These are were faster, and durable

Attaching to cpu was expensive , time consuming

Difficult to change it

Micro progam Consists of memory chip that runs small

programs. ( circuits)

These programs send specific directions to each function of the machine.

This type of control unit is more popular and simple to install.

The microprogram unit sends distinct messages to certain parts of the machine to run effectively.

EXAMPLE• Advancement of technology• A Rather Large Control Unit

This is the CPU control unit of the ILIAC IV computer in the 1960s. Today, the equivalent circuitry fits on the head of a pin. (Image courtesy of The Computer Museum History Center

ARITHMETIC LOGIC UNIT

PRESENTER>>>BIBOY NYAZWIGO

The first is the arithmetic logic unit (ALU), which performs simple arithmetic and logical operations. An ALU is a fundamental building block of many types of computing circuits, including the central processing unit (CPU) of computers, FPUs, and graphics processing units (GPUs).The inputs to an ALU are the data to be operated on, called operands, and a code indicating the operation to be performed; the ALU's output is the result of the performed operation. In many designs, the ALU also exchanges additional information with a status register, which relates to the result of the current or previous operations.

THE ARIHMETIC LOGIC UNIT (ALU)

SIGNALS

DATAA basic ALU has three parallel data buses consisting of two input operands (A and B) and a result output (Y). Each data bus is a group of signals that conveys one binary integer number. Typically, the A, B and Y bus widths (the number of signals comprising each bus) are identical and match the native word size of the encapsulating CPU (or other processor).

CIRCUIT OPERATIONSAn ALU is a combinational logic circuit, meaning that its outputs will change asynchronously in response to input changes. In normal operation, stable signals are applied to all of the ALU inputs and, when enough time (known as the "propagation delay") has passed for the signals to propagate through the ALU circuitry, the result of the ALU operation appears at the ALU outputs. The external circuitry connected to the ALU is responsible for ensuring the stability of ALU input signals throughout the operation, and for allowing sufficient time for the signals to propagate through the ALU before sampling the ALU result.

In general, external circuitry controls an ALU by applying signals to its inputs. Typically, the external circuitry employs sequential logic to control the ALU operation, which is paced by a clock signal of a sufficiently low frequency to ensure enough time for the ALU outputs to settle under worst-case conditions.

For example, a CPU begins an ALU addition operation by routing operands from their sources (which are usually registers) to the ALU's operand inputs, while the control unit simultaneously applies a value to the ALU's opcode input, configuring it to perform addition. At the same time, the CPU also routes the ALU result output to a destination register that will receive the sum. The ALU's input signals, which are held stable until the next clock, are allowed to propagate through the ALU and to the destination register while the CPU waits for the next clock. When the next clock arrives, the destination register stores the ALU result and, since the ALU operation has completed, the ALU inputs may be set up for the next ALU operation.

THE PROCESSO

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PRESENTER…TENDAI KARUMA

MAIN MEMORY…

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PRESENTER…MICHELLE MANYEKU

Memory or Storage Unit

• This unit can store instructions, data and intermediate results.

• It supplies information to other units of the computer when needed.

• Its also known as internal storage unit or main memory or primary storage or RANDOM ACCESS MEMORY(RAM).

• Its size affects speed, power and capability. Primary memory and secondary memory are two types of memories in the computer..

Functions of memory units

• It stores all the data and the instructions required for processing.• It stores intermediate results of processing.• It stores final results of processing before

these results are released to an output device.• All inputs and outputs are transmitted through

main memory

Physical Types of Memory

RAM (volatile or non-volatile)• Memory cards• External hard drive• Flash • Compact Disc• Tape• DVD

PICTORIAL DISPLAY

• ,

MAIN MEMORY

PIC DISPLAY,,,

CONT….

COMPARISON …

TYPES OF RAM

• -

REGISTER

BLESSING TARANGANAYI

WHAT EXACLY ARE REGITERS

• Register are used to quickly accept, store, and transfer data and instructions that are being used immediately by the CPU.

• In computer architecture, a processor register is a small amount of storage available as part of a digital processor, such as a central processing unit (CPU).

• Registers are used for performing the various Operations

• E.g While we are working on the System then Registers are used by the CPU for Performing the Operations. When We Gives Some Input to the System then the Input will be Stored into the Registers and When the System will gives us the Results after Processing then the Result will also be from the Registers. So that they are used by the CPU for Processing the Data which is given by the User.

Registers perform the following• Fetch =>The Fetch Operation is used for taking the instructions

those are given by the user and the Instructions those are stored into the Main Memory will be fetch by using Registers.

• Decode=>The Decode Operation is used for interpreting the Instructions means the Instructions are decoded means the CPU will find out which Operation is to be performed on the Instructions.

• Execute=>The Execute Operation is performed by the CPU. And Results those are produced by the CPU are then Stored into the Memory and after that they are displayed on the user Screen.

• MAR (memory address register)• PC (program counter)• AC (accumulator register)• MDR (memory data register)• DR (data register)• MBR( Memory buffer register)• ID (index register)

TYPES OF REGSTERS

PRESENTER>>>TARUVINGA

CATEGORIES OF REGISTERS

• USER VISIBLE REGISTERS• DATA REGISTERS• ……can be assigned by the user program to perform operations on

data

• ADDRESS REGISTERS • …...contain memory address of data and insructions• …….may contain a portion of an address that is used to calculate the

complete address.

• Examples of address Registers

• a; Index/Offset• Involves adding an index to a base value to get an address

• B, Segment pointer• ….when memory is divided into segments ,memory is referenced by a

by a segment and an offset.

• C, Stake pointer

• Points to the top of the stack

• D, Program status word • a register or group of registers containing the following

• *condition code and status information bits• *interrupt enable /disable bit• *supervise (os)/user mode bit

• Control and status registers

• …Generally not available to the user programs• ….Some registers are used by C P U to control its operation• ….Some are used by OS to control program execution

• Examples of control and status Registers

• A , Contains address of the next to be fetched

• B , Contains the instruction most recently fetched

SYSTEM BUS

PRESENTER…SAMUEL STROVER MAKOTA

System Bus

Computer Architecture

SYSTEM BUS•Group of wires which carries information form CPU to peripherals or vice –versa

•Single bus structure: Common bus used to communicate between peripherals and microprocessor

Buses• There are a number of possible

interconnection systems• Single and multiple BUS structures are most

common

What is a bus?• A communication pathway connecting two or

more devices• more devices share the same bus• Usually broadcast • Often grouped

• A number of channels in one bus• e.g. 32 bit data bus is 32 separate single bit

channels

Data Bus• Carries data• Remember that there is no difference

between “data” and “instruction” at this level• Width is a key determinant of performance• 8, 16, 32, 64 bit

Address bus• Identify the source or destination of data• e.g. CPU needs to read an instruction (data)

from a given location in memory• Bus width determines maximum memory

capacity of system– e.g. 8080 has 16 bit address bus giving 64k

address space

Control Bus• Control and timing information

– Memory read/write signal– Interrupt request

Bus Interconnection Scheme

CPU SCHEDULING

PRESENTER>>>PARTMORE KAPINGURA

PRESENTER>>>FARAI MAKAKANJE& PARTMORE KAPINGURA

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