Introduction to CPU architecture and motherboard
- Objectives: at the end of this lesson you shall be able to
- State what is hardware and test internal and external hardware
- Brief the listed hardware
- State what is partitions and their types
- Explain the booting and its procedures.
Computer Hardware
The physical units of a computer are called as the hardware of a computer.
Internal Hardware Examples:-
- Blu-Ray, CD-ROM, and DVD
- CPU
- HARD DRIVE
- MOTHERBOARD
- RAM
- SOUND CARD
- VIDEO CARD
- SMPS
External Hardware Examples
- Flat-Panel, Monitor and LCD
- Keyboard
- Mouse
- Printer
- Scanner
- CPU& ALU
Central processing unit(CPU) is the heart of the computer. It is the hardware that carries out the instructions of a computer program by performing the instructions of a computer program by performing the basic arithmetical, logical and input/output operations of the system.
CPU Ports and connectors
A port is a connector at the back of a computer cabinet where you plug in an external device such as a printer, keyboard, scanner, modem etc. this allows instructions and data to flow between the computer and the device. The computer ports are also commonly referred to as the input/output ports(I/O ports). These ports can be either serial or parallel. Fig 1 shows the commonly available ports on a personal computer.
Most connectors are separated, permitting the cable to be plugged in inly in the correct direction. The keyboard and mouse use “PS2” (Personal System 2) connectors. The PS2 connectors are color-coded. The purple connector is for the keyboard. The green connector is for the mouse.
PS/2 Ports
Standard keyboards and mouse often connect to the computer via the PS/2 ports. To plug in a keyboard or mouse cable, first match the cable to the connector. Then push the cable into the connector. Be sure not to force the connector because you will end up bending the pins.
Serial &Parallel Ports:-
The serial port and parallel port allow connections to printers and other external devices. To transfer a byte through a serial port, eight bits are queued and sent bit by bit. However in a parallel port, all the eight bits are transferred simultaneously.
The parallel port, serial port, and video port all use “D” type connectors (DB-25M,DB-9M,and DB-15F respectively). These are called D connectors because of their shape, which permits the cables to be plugged on only one way.
USB(universal Serial Bus) Ports
Devices like digital cameras, scanners and printers often connect to he motherboard via the USB ports. A USB connector’s distinctive rectangular shape makes it easily recognizable.
USB has a number of features that makes it particularly popular on PCs. First, USB devices are hot swappable. You can insert or remove them without restarting your system.
LAN (Local AREA Network) Port:-
The LAN port is used to connect the PC to a local network or the high speed Internet services.
VGA(Video Graphics Array) Ports:-
The VGA Port provides access to integrated video.
Audio Ports:-
It provides access to integrated audio. The audio jacks are the most confusing connectors on the back panel. Although the jacks are sometimes color-coded, the devices that plug into them rarely.
CPU Front Panel shown flg2.
It may contain the following parts.
- Power on/off switch
- Power indicator
- CD/DVD Drive
- CD/DVD Drive Open/Close Button
- CD/DVD Drive Indicator
- Floppy Disk Drive
- Floppy Disk Drive Indicator
- USB Ports
- Audio and Mic Connectors
|
Design of CPU Cabinets may very based on the manufacturer. |
The system unit and its components
The system unit is a box-like unit filled with a number of useful components, each performing a discrete function. These components work together to accomplish the main function of the computer, viz. accept and process input and deliver output. This section will elaborate on these components one by one. Fig 3 show the various components of the system unit.
Power Supply
The power supply connects to nearly every device in the PC to provide power. It is located at the rear of the case. The system unit draws power form the AC mains through a power protection device.
This power is not directly supplied to the internal components. Instead, one of the components, called the internal power supply, converts the AC input into DC output of 5 and 12 volts. Normally, the internal power supply is referred to as Switched Mode Power Supply(SMPS).
The SMPS provides cable connectors to supply the required voltage to the other internal components like the floppy drives the hard disk drive, the motherboard and external device such as the keyboard. The ON/OFF switch of the system unit is actually a part of SMPS.
Fan
The SMPS has a small fan. Called the exhaust fan, attached to SMPS(Fig 4). This fan rotates as long as the computer is switched on. Its function is to cool the SMPS unit.
Drive Bays:-
The 5.25” and 3.5” drive bays house the many kinds of storage devices a computer might contain.
Expansion Slots:-
An expansion slot is a slot located inside a computer mother bard that allow additional peripherals to be connected to it.
Memory slot:-
Memory slot is used to insert a Random Access Memory(RAM) shown in fig 5
Storage Drivers
Storage drivers such as hard drives, optical drives and floppy drives all connect to the motherboard via cables and is mounted inside the computer.
IDE & SATA Cables:-
Fig 6 shows two hard disk drives that connect in different ways to the motherboard. One uses the older IDE cable connection while the other uses SATA(Serial Advanced Technology Attachment) cable which provides for faster hard drive access.
Power Port:-
Power is delivered to drives via cables that plug into the power port in the drives.
Peripheral cards slot
The peripheral cards are the spare expansion slots available in the mother board on which peripheral cards can be inserted.
The following are the peripheral cards
- Sound card
- Video card
- Modam
- Wireless network
Fig 7 shows the peripheral card designed with a PCL(Peripheral Component Interconnect) connector.
Motherboard
The motherboard is a printed circuit that is the foundation of a computer and allows the CPU, RAM, and all other computer hardware components to function with each other as on fig 8.
The motherboard is the primary component of the entire system. A mother board is a large board containing a number of tiny electronic circuits and other components are visible. All peripheral devices are connected to the motherboard. The components of the motherboard are.
- Keyboard/ Mouse port
- Parallel and serial port
- Processor Socket
- AGP Slot
- PCI Slots
- ISA Slot
- CMOS Battery
- Data Card Connector
- Memory Slots
- Floppy Port
- Fan Header
- Main Power Connector
Floppy port :
The floppy drive connects to the computer via a 34- pin ribbon cable, which in turn connects to the motherboard. A floppy controller is one that is used to control the floppy drive.
RAM Slots:
Random-Access Memory(RAM) stores programs and data currently being used by the CPU.
RAM is measured in units called bytes. RAM has been packaged in many different ways.
SIMM-Single inline memory module-32 or 72 pin
DIMM-dual inline memory module-168 pin.
In most of the PC’s uses of the DIMM module.
ROM BIOS Chip:
This means Read Only Memory Basic Input-Output System.
The built-in software that determines what a computer can do without accessing programs form a disk. On PCs, the BIOS contains all the code required to control the keyboard, display screen disk drives, serial communications, and a number of miscellaneous functions.
The BIOS is typically placed in a ROM Chip that comes with the computer(it is often called a ROM BIOS). This ensures that the BIOS will always be available and will not be damaged by disk failures.
It also makes it possible for a computer to boot itself. Because RAM is faster than ROM, thought many computer manufacturers design systems so that the BIOS is copied form ROM to RAM each time the computer is booted, this is known Asshadowing.
Many modern PCs have flash BIOS, which means that the BIOS have been recorded on a flash memory chip, which can be updated if necessary. The PC bios is fairly standardized, so all PCs are similar at this level(although there are different BIOS versions). Additional DOS functions are usually added through software modules.
This means you can upgrade to a newer version of DOS without changing the BIOS. PC BIOS that can handle Plug-and-play(PNP) devices are known as PNPBIOS, these BIOS are always implemented with flash memory rather than ROM.
CMOS Battery
CMOS(Complementary Metal-Oxide-Semiconductor) is the term usually used to describe the small amount of memory on a computer motherboard that stores the BIOS settings.
Most CMOS batteries will last the lifetime of a motherboard (up to 10 years in most cases) But will sometimes need to be replaced, Incorrect or slow system date and time and loss of BIOS settings are major signs of a dead or dying CMOS battery.
ISA Slot:
(Industry Standard Architecture) it is the standard architecture of the expansion bus. Motherboard may contain some slots to connect ISA compatible cards.
PCI Slot:
Intel introduced the peripheral component interconnect bus protocol. The PCI bus is used to connect I/O devices to the main logic of the computer. PCI bus has replaced the ISA bus has replaced the ISA bus. PC motherboards have one PCI slot but generally more than one.
The PCI bus architecture is a processor-independent bus specification that allows peripherals to access system memory directly without using the CPU.
AGP Slot:
The accelerates Graphics Part(AGP) is a high-speed point-to-point channel for attaching a video card to a computer’s motherboard.
Power Supply Plug In
The Power supply, as its name implies, provides the necessary electrical power to make the PC(Personal Computer) operate. The power supply takes standard 110-V AC power and converts into +/- 12-Volt,+/-5-Volt, and 3.3-Volt DC power. The power supply connector has 20-pins, and the connector can go in only one direction.
