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ITT Course – Unit I. Chapter 2 Parts of Computer. Learning Objectives. To understand the various functions of CPU To know the concept of Virtual Memory To discuss about Bus, add-on cards, motherboard, sound card and expansion slots. An Introduction.
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ITT Course – Unit I Chapter 2 Parts of Computer
Learning Objectives • To understand the various functions of CPU • To know the concept of Virtual Memory • To discuss about Bus, add-on cards, motherboard, sound card and expansion slots
An Introduction A computer is really a system of many parts working together. The physical parts, which you can see and touch, are collectively called hardware.
Typical PC Hardware Hardware of PC:-1. Monitor2. Motherboard3. CPU4. RAM Memory5. Expansion card6. Power supply7. CD-ROM Drive8. Hard Disk9. Keyboard10. Mouse
Common Computer Architecture • Computers come in different forms, but most of them have a common architecture. • All computers have a CPU • All computers have some kind of data bus which lets them get inputs or output things to the environment. • All computers have some form of memory. These are usually chips (integrated circuits) which can hold information. • Many computers have some kind of sensors, which lets them get input from their environment. • Many computers have some kind of display device, which lets them show output. They may also have other peripheral devices connected.
Basic Computer Components (at a glance…) • Case (Computer Cabinet) • Power Supply • Motherboard • Microprocessor • Memory • Drive Controllers • Hard Disk Drive • CD-ROM Drive • Floppy Drive • DVD Drive • Monitor • Keyboard • Mouse
Case (Computer Cabinet) • There are two basic styles of cases the computer may come assembled in as follows:- • Tower Style Case • Desktop Style Case Front View Rear View
Desktop Style Case Desktop style is in the shape of a rectangular box, that sets flat on a desk. Usually the computer monitor is placed on top of it.
Tower Style Case • A tower case, looks similar to a tower and are placed off to the side of the keyboard and monitor. • The tower case is the most popular style of desktop computer today. • Tower cases comes in varied sizes as mini tower, mid tower and full tower.
Computer Case Related Terminology Pin - A part of a connector that extends outward to extend into and make contact with a socket. Referred to as the male side of a connector. Socket - A part of a connector that contains an internal contact to receive the extended side (pin) of a connector. Referred to as the female side of a connector. Jack - A receptacle where power of signal connectors may be plugged into. These are usually on the case of a computer or the motherboard and are made to receive plugs from devices such as keyboards. Plug - The part that connects with the jack, which comes from a keyboard, mouse, monitor or other device. This is the side associated with a cable.
SMPS A SMPS (Switched-Mode Power Supply is an electronic PSU (Power Supply Unit) that incorporates a switching regulator in order to provide the required output voltage. It attempts to produce a smoothed, constant-voltage, output from a varying input voltage.
Inside SMPS • Legend: • A - bridge rectifier • B - input filter capacitors • C - transformer • D - output filter coil • E - output filter capacitors
Motherboard A motherboard is the central printed circuit board (PCB) in a modern computers, and holds many components of the system, while providing connectors for other peripherals. • A typical desktop computer has its microprocessor, main memory, and other essential components on the motherboard. • Components such as external storage, controllers for video display & sound, and peripheral • devices may be attached to the motherboard as plug-in cards or via cables. “In modern computers it is increasingly common to integrate some of the above mentioned peripherals into the motherboard itself.”
Modern Motherboard Configuration • Sockets (or slots) in which one or more microprocessors are installed. • Slots into which the system's main memory is installed. • A chipset which forms an interface between the CPU's front-side bus, main memory, and peripheral buses. • Non-volatile memory chips (usually Flash ROM in modern motherboards) containing the system's firmware or BIOS • A clock generator which produces the system clock signal to synchronize the various components • Slots for expansion cards (these interface to the system via the buses supported by the chipset) • Power connectors flickers, which receive electrical power from the computer power supply and distribute it to the CPU, chipset, main memory, and expansion cards. • logic and connectors to support commonly-used input devices, such as PS/2 connectors for a mouse and keyboard. • Additional peripherals such as disk controllers and serial ports were provided as expansion cards.
Role of Motherboard Organization of Devices: Everything is connected to the motherboard & the way that the motherboard is designed dictates how the entire computer is going to be organized. Control of the Devices: Built-in to the motherboard is the chipset and BIOS program, which between them control the majority of data flow throughout the different computer systems. System Communication: Almost all communication between the PC and its peripherals, other PCs, and, the user, goes through the motherboard. Processor Support: The motherboard socket depicts which choice of processor can be used in the system. Peripheral Support: The motherboards components determine what type of peripherals can be used in the PC. For example, you can not use AGP cards if you only have PCI slots. System Performance: The motherboard is a major factor in your system's performance as it dictates which type of processors, memory, system buses, and hard disk interface speed the system can have via its connectors or BIOS settings. Upgradeability: As motherboards are developed newer processors may not be compatible with the hardware as limitations of the circuitry built-in to the board itself will not allow them to run. As a result a user can look for any upgrades.
Modern Motherboard (Block Diagram) • Modern Motherboard supports many on-board peripheral functions as well as several expansion slots. • It is now possible to include support for many peripherals on the motherboard by combining many functions on one PCB • The physical size and total cost of the system may be reduced & highly-integrated motherboards can be produced.
Bus • A 'bus' is a set of wires or copper tracks that are built into the motherboard. • A bus is a parallel data communication path over which information is transferred a byte or word at a time. • The buses contain logic that the CPU controls. • The items controlled are the transfer of data, instructions, and commands between the functional areas of the computer: CPU, memory, and I/O. • The direction of signal flow for the different buses may be unidirectional or bidirectional depending on the type of bus and type of computer. • Need for a Bus:- • The CPU needs to move information in and out of memory. • Data needs to move between the hard disk and the CPU. • Data needs to move between the graphics card and the CPU • Data needs to move between the CDROM / DVD and the CPU • External buses such as USB can transfer data in & out of computer.
Types of Buses All computers use three types of basic buses. The name of the bus is generally determined by the type of signal it is carrying or the method of operation. Following are the types of buses:- Data Bus: These buses carry data from one unit to other, it is a bi-directional bus i.e., the data can be carried in both directions. Address Bus: These buses carry address given by the CPU from one unit to another in the computer. Control Bus: These buses carry control signal from ALU to memory and from memory to ALU and then to the output unit.
Data Bus The bidirectional data bus, sometimes called the memory bus, handles the transfer of all data and instructions between functional areas of the computer. The bidirectional data bus can only transmit in one direction at a time. The data bus is used to transfer instructions from memory to the CPU for execution. It carries data (operands) to and from the CPU and memory as required by instruction translation. The data bus is also used to transfer data between memory and the I/O section during input/output operations. • A bus usually contains between 1 to 64 wires or more, the no. of wires equals the number of 'bits' that can be transferred in one clock cycle. • An 8 bit bus has 8 wires - it can transfer 8 bits in one go, with 1 bit on each wire. • A 16 bit bus can transfer 16 bits in one cycle - 1 bit per wire.
Address Bus The address bus consists of all the signals necessary to define any of the possible memory address locations within the computer, or for modular memories any of the possible memory address locations within a module. An address is defined as a label, symbol, or other set of characters used to designate a location or register where information is stored. Before data or instructions can be written into or read from memory by the CPU or I/O sections, an address must be transmitted to memory over the address bus. • The number of lines in the address bus determines the amount of memory that can be directly addressed as each line carries one bit of the address. • A computer with a 32-bit address bus can directly address 4GB of physical memory, while one with 36 bits can address 64GB.
Control Bus The control bus is used by the CPU to direct and monitor the actions of the other functional areas of the computer. It is used to transmit a variety of individual signals (read, write, interrupt, acknowledge, etc.) necessary to control & coordinate the operations of the computer.
Other Classification of Bus • Buses can be parallel buses, which carry data words in parallel on multiple wires, or serial buses, which carry data in bit-serial form. • Most computers have both internal and external buses. An internal bus connects all the internal components of a computer to the motherboard (and thus, the CPU and internal memory). These types of buses are also referred to as a local bus, because they are intended to connect to local devices, not to those in other machines or external to the computer. An external bus connects external peripherals to the motherboard. • Examples of external computer buses : • Parallel • SCSI (Small Computer System Interface) • ATA (Advanced Technology Attachment) • Serial • USB (Universal Serial Bus) • Serial ATA • Examples of internal computer buses : • Parallel • ISA (Industry Standard Architecture) • Multibus for Industrial Systems • Serial • 1-Wire • PCI Express
Input – Output Ports / Interface Input-output ports are material elements on the computer, allowing the system to communicate with exterior elements, in other words to exchange data, hence the name input-output interface.
Serial Ports / Interface • Serial ports (also called RS-232, after the name of the standard they refer to) represent the first interfaces to allow computers to exchange information with the "outside world". • The term serial refers to data sent via a single wire: the bits are sent one after the other. • A personal computer generally has between one and four serial ports. Serial connectors generally have 9 or 25 pins and take the above form as DB9 & DB25 connectors respectively
Parallel Ports / Interface • Parallel data transmission involves sending data simultaneously on several channels (wires). The parallel ports on personal computers can be used to send 8 bits (one octet) simultaneously via 8 wires. Parallel ports, like serial ports, are built into the mother board. DB25 connectors allow connection to an exterior element (e.g. a printer).
CPU • The Central Processing Unit (CPU) or processor is the portion of a computer system that carries out the instructions of a computer program, and is the primary element carrying out the computer's functions. • It controls all internal and external devices, performs arithmetic and logic operations. • It interprets and carries out, or processes, instructions and data contained in the software.
Arithmetic Logical Unit • The arithmetic and logic unit (ALU) is the part where actual computations take place. It consists of circuits which perform arithmetic operations (e.g. addition, subtraction, multiplication, division) over data received from memory and capable to compare numbers. • While performing these operations the ALU takes data from the temporary storage area inside the CPU named registers.
Registers • Registers are a small amount of memory locations built into the CPU. • Registers are a group of cells used for memory addressing, data manipulation and processing. • Some of the registers are general purpose and some are reserved for certain functions. • It is a high-speed memory which holds only data for immediate processing and results of this processing. • If these results are not needed for the next instruction, they are sent back to the main memory and registers are occupied by the new data used in the next instruction.
Basic Register Types (differentiated by CPU architecture) Basic Registers System Registers Operating systems and application programs access Basic Registers via instructions in order to store code / data / state information, change / compare data and transfer / change program flow. The System Registers are mainly used by operating systems and system development programs (e.g. compilers). Types of Registers
Data Register User Accessible Register Index Register Address Register Conditional Register Stack Register General Purpose Register Floating Point Register Constant Register Vector Register Program Counter Special Purpose Register Instruction Register Model Specific Register Program Status Word Control & Status Register Categories of Registers
Registers Categories (Explained) User-accessible Registers User-accessible registers are divided into data registers & address registers. Data registers are used to hold numeric values such as integer and floating-point values. Address registers hold addresses and are used by instructions that indirectly access memory. Index registers are used for a special kind of indirect addressing where an immediate constant (i.e. which is part of the instruction itself) is added to the contents of a register to form the address to the actual operand or data. Stack register can be used by some instructions to maintain a stack (data structure). Conditional registers hold truth values often used to determine whether some instruction should or should not be executed. General purpose registers can store both data and addresses, i.e., they are combined Data / Address registers. Floating point registers store floating point numbers in many architectures. Constant registers hold read-only values such as zero, one, or pi. Vector registers hold data for vector processing done by SIMD instructions (Single Instruction, Multiple Data). Special purpose registers hold program state; they usually include the program counter , stack pointer, and status register . Model-specific registers store data and settings related to the processor itself. Control and status registers has three types. Program counter, instruction registers, Program status word.
Facts about CPU • The Central Processing Unit (CPU) is the brain of the computer. • Modern CPU's are what are called 'integrated chips'. • The CPU is composed of thousands of transistors. • Each transistor is a set of inputs and outputs. When the inputs receive electricity, the combined charge changes the state of the transistor internally and you get a result out the other side. This simple effect of the transistor is what makes it possible for the computer to count and perform logical operations, all of which we call processing. • The CPU attaches directly to a CPU "socket" on the motherboard. The CPU is inserted into the socket pin-side-down and a small lever helps to secure the processor. • After running, modern CPUs can get very hot. To help dissipate this heat, it is necessary to attach a heat sink and a small fan directly on top of the CPU. • A CPU usually contains an execution core with two or more pipelines, a data and address bus, a dedicated arithmetic logic unit (ALU, also called the math co-processor), and in some cases special high-speed memory for caching program instructions from RAM. • The CPU's in most PC's and servers are general purpose integrated chips composed of several smaller dedicated-purpose components which together create the processing capabilities of the modern computer.
CPU Operation The fundamental operation of most CPUs is to execute a sequence of stored instructions called a program. The program is represented by a series of numbers that are kept in some kind of computer memory. There are four steps that nearly all CPUs use in their operation: fetch, decode, execute, and writeback. Step 1: The first step, fetch, involves retrieving an instruction from program memory. Step 2: the decodestep, the instruction is broken up into parts that have significance to other portions of the CPU. Step 3: the executestep is performed during which the various portions of the CPU are connected so they can perform the desired operation. Step 4: The final step, writeback, simply "writes back" the results of the execute step to some form of memory.
Processing device Control unit ALU (2) Decode (3) Execute I-time E-time Registers (1) Fetch (4) Store Memory CPU Operation (Diagrammatic View)
CPU Components • Execution Core • Data Bus • Address Bus • Math Co-processor • Instruction sets / Microcode • Multimedia extensions • Registers • Flags • Pipelining • Memory Controller • High-Speed Cache Memory
Processor Manufacturer American Micro Devices (AMD) Intel Motorola IBM Texas Instruments Cyrix
Expansion Slots An opening in a computer where a circuit board can be inserted to add new capabilities to the computer. The primary purpose of an expansion card is to provide or expand on features not offered by the motherboard. Expansion Slots are used for adding more memory, graphics capabilities, and support for special devices. The boards inserted into the expansion slots are called expansion boards, expansion cards, cards , add-ins , and add-ons.
Expansion Slot Standards • PCI Express (Peripheral Component Interconnect Express) • AGP (Accelerated Graphics Port) • PCI (Peripheral Component Interconnect) • ISA (international Standard Architecture)
Expansion Slot Standards PCI a computer bus for attaching hardware devices in a computer. Typical PCI cards used in PCs include network cards, sound cards, modems, extra ports such as USB or serial, TV tuner cards and disk controllers. PCI Express is a computer expansion card standard designed to replace the older PCI, PCI-X, and AGP standards. PCI Express is used in consumer, server, and industrial applications, as a motherboard-level interconnect. AGP is a high-speed point-to-point channel for attaching a video card to a computer's motherboard, primarily to assist in the acceleration of 3D computer graphics. ISA is all but gone today Apart from specialized industrial use.
Computer Data Storage • Computer data storage, often called storage or memory, refers to computer components, devices, and recording media that retain digital data used for computing for some interval of time. • Computer data storage provides one of the core functions of the modern computer, that of information retention.
Storage Terminologies • A digital computer represents data using the binary numeral system. • Text, numbers, pictures, audio, and nearly any other form of information can be converted into a string of bits, or binary digits, each of which has a value of 1 or 0. • The most common unit of storage is the byte, equal to 8 bits. • 1 Byte = 8 bits • 1 Kilobyte (KB) = 1024 bytes • 1 Megabyte (MB) = 1024 KB • 1 Gigabyte (GB) = 1024 MB • 1 Terabyte (TB) = 1024 GB
Storage Hierarchy Various forms of storage, divided according to their distance from the central processing unit. The fundamental components of a general-purpose computer are arithmetic and logic unit, control circuitry, storage space, and input/output devices.
Computer Memory Computer systems use memory to store data. Memory should not be confused with hard disk space. In general, memory is used for programs and data that are currently being used. Hard disks store data permanently.
Primary Storage / Main Memory • Main memory is a device that records data and programs within a computer. • It is also called "Main storage unit“ or “Primary Storage”. • This memory is the only one which is directly accessible to the CPU. • The CPU continuously reads instructions stored there and executes them as required. • It uses semiconductor elements to record electrically, which makes it possible to perform fast operation and to read and write directly from CPU. • It cannot be used in large quantities because the price for each unit is high.
Processor Register • They are located inside the processor. • Each register typically holds a word of data (often 32 or 64 bits). • CPU instructions instruct the arithmetic and logic unit to perform various calculations or other operations on this data. • Registers are technically among the fastest of all forms of computer data storage.
