1 Intro to Info Tech System Unit Copyright 2003 by Janson Industries This presentation can be viewed on line at:

1

Intro to Info TechSystem Unit

Copyright 2003 by Janson Industries

This presentation can be viewed on line at: http://web.fscj.edu/Janson/cgs1060/wk05.SystemUnit.ppt

Copyright 2012 by Janson Industries2

Objectives

▀ Explain the system unit and processing unit's components

▀ Explain how the components work together


System Unit▀ Different types of computers will

have different components

▀ Hand-held will have all components in System Unit♦ Monitor, Keyboard, Pointer, etc

▀ PC's System Unit has storage devices but Mainframes don't ♦ Secondary Storage is physically

separated from the MF System Unit


System Unit▀ Definition:

♦ The h/w that houses the processing unit components

▀ In desktop PCs: ♦ Usually a plastic or metal box that also

contains non-processing components like drives

♦ Processing components are stored on a mother board

● This is also often true for larger and smaller computers


System Unit▀ Comprised of:

♦ CPU♦ Internal Memory♦ Expansion Slots ♦ Bus♦ Ports

▀ Lots of different internal memory♦ RAM♦ ROM♦ Flash


Internal Memory▀ RAM: Random Access Memory

♦ Volatile, chip based♦ Commonly known as Main

Memory♦ Holds programs and data that are

currently being worked on

▀ ROM: Read Only Memory♦ Non-volatile, chip based♦ Holds the most basic instructions

of the computer


Internal Memory Flash

Non-volatile, chip based Doesn’t need electricity to retain info Holds computer start up instructions

and system info System time, date

Chip based memory is fast 200,000 X faster than a hard drive

Approx 10 nanoseconds to retrieve data

Also measured by size Mega/Gigabytes (m/billions of bytes)


Memory Size▀ Byte = 8 bits = 2 nibbles

▀ A character can be represented with one byte

▀ Lots a different Binary Representation Systems♦ EBCDIC♦ ASCII♦ Unicode

● Gather round. I want to tell you about Snow White and the 7 dwarfs....


Internal Memory▀ System Unit may have many RAM

chips, Flash chips, etc.♦ Total RAM usually gigabytes (billions)♦ Usually can add more to your system

▀ Often some RAM etched onto same chip as the CPU♦ Speeds up access

''

▀ Can have specialty memory♦ i.e. memory that stores and retrieves

video, images faster


Internal Memory▀ Many chips stored on a module

♦ Module is a 3 dimensional circuit board

▀ Module stored on board/card

▀ Board/card goes into a expansion slot and (often) snaps into the mother board

▀ Lots of different cards to add or enhance functionality♦ Video card, sound card, network card

''


CPU▀ To understand IM, must understand

how the CPU works with it♦ Book diagram (Fig 4-4) is misleading

▀ CPU on a single chip (called a microprocessor), comprised of 2 pieces:♦ CU – Control Unit♦ ALU – Arithmetic Logic Unit

▀ Can have multiple CPUs and/or multiple CPU's on a chip


CPU▀ CU manages all communication

and memory

▀ ALU does math and comparisons

Disk Drive

Main Memory

CPU

Monitor

Keyboard

CU

ALU


The Machine Cycle▀ The steps the CPU goes through to

perform one instruction♦ Get instruction from MM – CU♦ Decode the instruction and send to

the ALU – CU♦ Instruction performed – ALU♦ Instruction result moved into MM – CU

▀ The next instruction might be "display the result" or "save the result on disk"


Suppliers For PC's, Intel (IBM chose their

chip/design in 1980) 8086, 286, 386, 486, Pentium,

Itanium, etc. Lots of clones: AMD, Transmeta

IBM: Supercomputers, MFs, game consoles

Motorola: communication devices


Suppliers For mobile devices, ARM (Advanced

RISC Machine) chips used Intel chips are CISC (Complex

Instruction Set Computer)

ARM chips have lower power consumption so majority of mobile devices use them to extend battery life

Windows 8 runs on ARM ARM mfgs will be going after PC and server

market!


CPU Measured by speed

Lots of different methods Clock speed measures how many

cycles are completed per second Cycle = hertz Gigahertz = 1 billion cycles/second

Mfgs will argue about what can be done in a cycle FLOPS – Floating Point Operations Gigaflops, Teraflops


Ports Essentially sockets for connecting

peripheral devices Serial - one bit at a time Parallel – multiple channels USB (Universal Serial Bus)

Connects many types of devices Lots of other specialty ports:

Head phone Microphone Telephone


Ports Limited number of ports on a

computer Hubs allow you to connect many

devices to a single port


Bus The wiring that connects all the

processing unit components Ports to the CPU The CPU to Main Memory Expansion slots to the CPU

Larger computers can have multiple buses

Measured by How many bits at a time (64 bit bus) Clock speed (1 GHz)


System Unit PCs also have bays

System Unit opening that can hold a device

Internal and External Internal holds Hard drive External holds CD, DVD drive

Laptop may have only 1 bay Can slap in a CD, Floppy, or

DVD drive


What do you need?

What do you want to do with the computer?

This dictates application s/w

Application s/w dictates: OS H/W – memory, video card Peripherals


Points to Remember▀ System Unit houses the processing

components of a computer

▀ In PCs, will also have secondary storage devices

▀ Many factors determine a computer's speed♦ Chip speed, bus speed, amount of

internal memory

Documents

1 Intro to Info Tech System Unit Copyright 2003 by Janson Industries This presentation can be viewed on line at: