cs100 lec 3 cont1 hardware - system unit and memory)

3 Fundamental Elements of a Computer

• Work like a team to complete tasks

1. System Unit

2. Output Devices

3. Input Devices

System Unit

• The core of a computer responsible for processing and storing data and controls all computer functions

• It is where data are processed into information

• It works with peripheral devices

System Unit• System Case – a plastic and metal box that houses components such as

the motherboard, disk drives, power supply and etc.– System Case Types

1. Desktop – designed to sit horizontally2. Tower – designed to sit verticallya. Full-tower case

- used for PC servers- requires extra space for additional hard disks,

interface cards and redundant power supplyb. Midi-tower case

- usually used for high-end user PCs-require extra devices and interface cards but not asmany as a server

c. Mini-tower case- used for office or home PCs- where additional internal devices and interface cards

are limited

FULL TOWER

MIDI TOWER

MINI TOWER

System Unit:

Motherboard

Microprocessor or (CPU)

Memory Chips

Ports

Buses

Expansion Slots and cards

Motherboard• “System Board”

•  is the main printed, flat circuit board in an

electronic device such as microcomputers.

The board contains expansion slots (sockets)

that accept additional boards (expansion

Cards).

The motherboard contains: microprocessor the primary storage chips (or main memory

cards) Buses and all the chips used for controlling the

peripherals.

Microprocessor• A microprocessor is a processor whose

elements are miniaturized into one or a few integrated circuits contained in a single silicon microchip. It executes instructions.

• In a microcomputer, the central processing unit (CPU) is held on a single microprocessor.

• In order to function as a processor, it requires a system clock, primary storage, and power supply.

Central Processing Unit (CPU)

• is the computing part of the computer that interprets and executes program instructions.

• It is also known as the processor. • In a microcomputer, the CPU is contained on a

single microprocessor chip within the system unit.

• The CPU has two parts: the control unit and the arithmetic-logic unit.

Control Unit

• is the circuitry that locates, retrieves, interprets and executes each instruction in the central processing unit.

• The control unit directs electronic signals between primary storage and the ALU, and between the CPU and input/output devices.

Arithmetic Logic Unit (ALU)• is a high-speed circuit part in the CPU.• performs arithmetic (math) operations, logic

(comparison) operations and related operations. • The ALU retrieves alphanumeric data from

memory and then does actual calculating and comparing. It sends the results of the operation back to memory again.

Chip• is an integrated circuit. • Microscopic circuit board is engraved in a chip

made by silicon. Chips are approximately 1/16- to 1/2-inch square and about 1/30-inch thick.

• Chips hold a few dozen to several million transistors.

• A chip is also called an integrated circuit, microelectronic, semiconductor, or silicon chip.

• For example, an Intel Pentium chip has 3.2 million and Pentium Pro has about 6 million transistors.

Storage Devices (Memory) : 2 types of memory- Main / Primary- Secondary

Main / Primary / RAM• Closely connected

to the processor• Quickly and easily

change, volatile• Holds the programs

and data that the processor is actively working with

• Interacts with the processor millions of times per second

Types of RAM

1. Dynamic RAM (DRAM) – constantly refreshed by the CPU or it will lose its contents

2. Synchronous DRAM (SDRAM) – synchronous by the system clock and is much faster than DRAM

3. Static RAM (SRAM) – faster than any DRAM and will retain its contents w/o having to be refreshed by the CPU

4. Rambus DRAM – faster and more expensive than SDRAM and is the type of memory used with Intel’s P4 chip

DYNAMIC RAM

SDRAM

RAMBUS DRAM SRAM

Secondary• Slow compared to

main memory• Used for long-term

storage of programs and data, non-volatile

Ex. • Floppy disk• ZIP Disk• SuperDisks • HiFD Disk • Flash Disk • Memory Card• Hard disk• Optical disk• Magnetic tape

Secondary Storage

1. Floppy Disk (1.44 MB) –also called as diskette or disk, is a removable flat piece of mylar plastic package in a 3.5-inch plastic case.

8“ floppy disk (large floppy)5 ¼“ floppy disk (minifloppy)31/2” floppy disk (micro floppy)

2. ZIP Disk (100 to 250 MB) – special disks that uses their own ZIP disk drive.

3. SuperDisks (120 MB) – uses a SuperDisk Drive and can also read standard 1.44 MB floppy disk, which a ZIP drive cannot do.

4. HiFD Disk (200 MB) – uses a HiFD drive and can also read standard 1.44 MB floppy disk.

5. Flash Disk (128 MB to 16GB) – uses the USB6. Memory Card (16 MB – 2GB) – used in cameras, cellphones

8”, 5.25”, 3.5” floppy disks

8”, 5.25”, 3.5” floppy disk drives

ZIP DISK

SuperDISK

HiFD DISK

FLASH DISK MEMORY CARD

Hard Disk– are made up of thin but rigid metal platters covered

with a substance that allows data to be held in the form of magnetized spots.

• Nonremovable hard disk – also known as fixed disk, is housed in a microcomputer system unit and is used to store nearly all programs and most data files.

• Removable hard disk – or hard disk cartridges, consist of one or two platters enclosed along with read/write heads in a hard plastic case, which is inserted into a microcomputer’s cartridge drive

REMOVABLE HARD DISK

NONREMOVABLE HARD DISK

Optical Disk– A removable disk, usually 4.75” in diameter and less than 1/20 of an

inch thick, on which data is written and read through the use of laser beams.

• Compact Disk Read Only Memory (CD-ROM) –can hold up to 650 MB of 300,000 pages of text

• Compact Disk-recordable (CD-R) – can be written to only once but can be read many times

• Compact Disk-rewritable (CD-RW) – also known as erasable optical disk

• Digital Versatile disk or digital video disk, with read only memory (DVD-ROM) – a CD-style disk with extremely high capacity, able to store 4.7 – 17 GB

• Universal Media Disk (UMD) – The disc is only two and a half inches wide and weighs only .35 ounces but it still has plenty of space for material with its 1.8 gigabyte capacity.

CD-ROM / CD-ROM DRIVE

CD-R

CD-RW

DVD-ROM

UMD

• Magnetic Tape– A thin plastic tape made up of mylar film

coated with iron oxide that can be magnetized.

Other Memories used in the computer

Read Only Memory Basic Input Output System (ROM BIOS)

• A chip that provides the industry's standard program code that operates the fundamental components of the PC

• The routines that allow the setup configuration of a PC

• The Power-on Self Test (POST) diagnostic tests for the PC

Complimentary Metal-Oxide Semiconductor Random Access memory

• Stores the configuration of the PC (password, disk types, amount of memory installed, current time and date). This prevents the need for reconfiguration when powering on a PC

CMOS RAM

ROM BIOS

Expansion Slots

• are receptacles inside a system unit that printed circuit boards (expansion boards) are plugged into.

• Computer buyers need to look at the number of expansion slots when they buy a computer, because the number of expansion slots decides future expansion.

• In microcomputers, the expansion slots are directly connected to the bus.

Expansion Boards

• are also called expansion cards, controller cards, plug-in boards, adapter cards, or interface cards.

• Expansion boards are printed circuit boards that have many electronic components including chips. They are plugged into expansion slots.

Ports

• A port is an external connecting socket on the outside the computer.

• This is a pathway into and out of the computer. • A port lets users plug in outside peripherals,

such as monitors, scanners and printers.

Bus• A bus is a data pathway between several

hardware components inside or outside a computer. It not only connects the parts of the CPU to each other, but also links the CPU with other important hardware.

• The other important hardware includes memory, a disk control unit, a terminal control unit, a printer control unit, and a communications control unit.