The System Unit

1
Chapter 4

• The System Unit

2
Binary Systems

• Computers use this system
• to process data
• Bi means two nary means number
• Two number system that uses 1 and 0
• 1 and 0 are bits
• 8 Bits 1 Byte
• 16 bites means youre eating too fast

3
How does Binary Code work?

• Computers dont speak our language.
• Pressing a key converts the character into
  electronic pulses recognized by computer.
• 3 0011 0011

4
So a computer reads like this

• 0011 1111 00001111 1010 0101
• 0101 1110 0001 1000 1110 1111
• 0101 1100 0010 0100 0100 1001
• 1101 0000 1110 0010 1100 0010
• 1000 1101 0101 1010 1110 1010
• 0001 0101 0101 1111 0110 0011
• 0000 1111 1010 0011 0011 0001

5
Binary Coding Schemes

• ASCII 8 bit. Used with Microcomputers. Most
  widely used.
• EBCDIC 8 bit. Developed by IBM for large
  computers.
• Unicode 16 bit. Used for international languages

6
Example of Unicode
7
The System Unit

• The of your computer
• A chassis or cabinet that houses most of the
  components of the computer

8
The System Unit has 3 parts

• System Board
• Microprocessor
• Memory

9
1. System Board

• The Motherboard
• All components connect to this board
• Allows all parts to communicate with each other

10
2. The CPU

• Central Processing Unit
• A chip
• The brains
• Contains 2 components
• The control unit tells the computer how to
  carry out instructions
• The arithmetic-logic unit (ALU)
• Performs math
• Performs comparisons
• I could use another ALU

11
Chips The details

• Measure speed by the number of bits accessed at
  one time.
• 64 bit is faster than 32 bit
• Two kinds of chips
• CISC (Intel)
• RISC (PowerPC) Simpler Cheaper
• Potato chips
• Chips Ahoy!

12
3. Memory is important

• Storage for data, instructions and information
• If your computer doesnt have enough memory, it
  will get Alzheimers

13
Memory is measured in

• KB kilobytes 1,000 bytes
• MB megabytes 1 million bytes
• GB gigabytes 1 billion bytes
• DB Dog Bites - Rabies

14
3 types of memory

• RAM Random Access
• ROM Read Only
• CMOS Complimentary Metal-Oxide Semiconductor
• Fond - Your favorite date
• Lost - What you learned last week

15
RAM Random Access Memory

• Volatile storage Temporary
• Be sure you have enough!
• New computers have Virtual Memory Caches

16
ROM Read only memory

• Built-in at the factory
• Cannot change the data
• Used for special computer instructions

17
CMOS

• A chip that supplies basic info about your
  computer
• Data can be changed
• Powered by a battery

18
Memory A summary

• RAM- Programs data (Expandable)
• ROM- Fixed start-up instructions
• CMOS- Flexible start-up instructions

19
Other Stuff you should know

• System clock electrical impulses used as a
  timing mechanism
• Speed is measured in Gigahertz
• Is she ever going to stop talking???

20
And more

• Expansion slots and cards
• Network cards
• Modem cards
• Sound cards
• Video TV tuner cards
• HELP, my brain is full!

21
And even more

• BUS lines
• Connect all parts of the CPU together
• A roadway for bits
• Each device needs one kind of bus line
• There are four
• ISA - Old
• PCI - 20 X faster than ISA
• AGP Graphics 2 X faster than PCI
• USB Todays standard high speed devices
• Phoenix City Bus

22
Oh, nonot more

• Ports
• Serial One bit at a time/Good for long
  distances - Mouse, keyboard, modem
• Parallel 8 bits over 8 wires/Good for lots of
  data over a short distance -Printer
• USB Faster/Used to connect multiple devices
• Firewire 33 X faster than USB
• Cables connect all devices to ports

23
Ports

• San Diego
• Seattle
• New York
• Miami

24
Devices plug into Ports