1. 1 Intro to Info Tech System Unit Copyright 2003 by Janson Industries This presentation can be viewed on line at: http://web.fscj.edu/Janson/cgs1060/wk05.SystemUnit.ppt

2. Copyright 2012 by Janson Industries 2 Objectives ▀ Explain the system unit and processing unit's components ▀ Explain how the components work together

3. Copyright 2012 by Janson Industries 3 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

4. Copyright 2012 by Janson Industries 4 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

5. Copyright 2012 by Janson Industries 5 System Unit ▀ Comprised of: ♦ CPU ♦ Internal Memory ♦ Expansion Slots ♦ Bus ♦ Ports ▀ Lots of different internal memory ♦ RAM ♦ ROM ♦ Flash

6. Copyright 2012 by Janson Industries 6 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

7. Copyright 2012 by Janson Industries 7 Internal Memory n Flash u Non-volatile, chip based F Doesn’t need electricity to retain info F Holds computer start up instructions and system info F System time, date n Chip based memory is fast u 200,000 X faster than a hard drive F Approx 10 nanoseconds to retrieve data u Also measured by size F Mega/Gigabytes (m/billions of bytes)

8. Copyright 2012 by Janson Industries 8 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....

9. Copyright 2012 by Janson Industries 9 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

10. Copyright 2012 by Janson Industries 10 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 ''

11. Copyright 2012 by Janson Industries 11 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

12. Copyright 2012 by Janson Industries 12 CPU ▀ CU manages all communication and memory ▀ ALU does math and comparisons Disk Drive Main Memory CPU Monitor Keyboard CU ALU

13. Copyright 2012 by Janson Industries 13 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"

14. Copyright 2012 by Janson Industries 14 Suppliers n For PC's, Intel (IBM chose their chip/design in 1980) n 8086, 286, 386, 486, Pentium, Itanium, etc. n Lots of clones: AMD, Transmeta n IBM: Supercomputers, MFs, game consoles n Motorola: communication devices

15. Copyright 2012 by Janson Industries 15 Suppliers n For mobile devices, ARM (Advanced RISC Machine) chips used n Intel chips are CISC (Complex Instruction Set Computer) n ARM chips have lower power consumption so majority of mobile devices use them to extend battery life n Windows 8 runs on ARM n ARM mfgs will be going after PC and server market!

16. Copyright 2012 by Janson Industries 16 CPU n Measured by speed n Lots of different methods n Clock speed measures how many cycles are completed per second n Cycle = hertz n Gigahertz = 1 billion cycles/second n Mfgs will argue about what can be done in a cycle n FLOPS – Floating Point Operations n Gigaflops, Teraflops

17. Copyright 2012 by Janson Industries 17 Ports n Essentially sockets for connecting peripheral devices n Serial - one bit at a time n Parallel – multiple channels n USB (Universal Serial Bus) n Connects many types of devices n Lots of other specialty ports: n Head phone n Microphone n Telephone

18. Copyright 2012 by Janson Industries 18 Ports n Limited number of ports on a computer n Hubs allow you to connect many devices to a single port

19. Copyright 2012 by Janson Industries 19 Bus n The wiring that connects all the processing unit components n Ports to the CPU n The CPU to Main Memory n Expansion slots to the CPU n Larger computers can have multiple buses n Measured by n How many bits at a time (64 bit bus) n Clock speed (1 GHz)

20. Copyright 2012 by Janson Industries 20 System Unit n PCs also have bays n System Unit opening that can hold a device n Internal and External n Internal holds Hard drive n External holds CD, DVD drive n Laptop may have only 1 bay n Can slap in a CD, Floppy, or DVD drive

21. Copyright 2012 by Janson Industries 21 What do you need? n What do you want to do with the computer? n This dictates application s/w n Application s/w dictates: n OS n H/W – memory, video card n Peripherals

22. Copyright 2012 by Janson Industries 22 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