1. Computers are your Future
Chapter 2

2. How Computers Represent Data
Bit
Single circuit
Binary digits
0 = no current/off
1 = current/on
Binary numbers
Series of binary digits
Byte
Group of 8 bits
Represents on character of data
Term
Bytes
Kilobyte
1 thousand
Megabyte
1 million
Gigabyte
1 billion
Terabyte
1 trillion

3. How Computers Represent Data
Other Codes
ASCII
Minicomputers PC
Computers making info available online
EBCDIC
Low to high ordered
Punctuation – lowercase letters – uppercase letters - numbers
Unicode
Represents more characters
Great of eastern languages
Hexadecimal
Uses numbers 0-9
Uses letters A-F
Each hex represents four binary digits
100
Binary =
Hexadecimal = 64

4. They System Unit
System Unit: box-like case that houses hardware components
Footprint: amount of space used by a device
Tower case: case designed to sit on the floor next to a desk
Minitower: smaller tower with less internal room
Form factor: specification for how internal components (like motherboard) are mounted inside the system unit.

5. Inside the System Unit
Motherboard: circuit board to which all other components are connected. Contains CPU (brain of the computer)
Power supply: transforms AC power from outlet to DC power needed for computer operation
Cooling fan: keeps computer from heat damage
Internal speaker: beeps with start-up or errors
Drive bays: accommodates disk drives
Expansion slots: allows expansion

6. Memory
The chip in the motherboard that retains instructions and data to be accessed by the CPU
RAM
Random Access Memory
Volatile (not permanent)
Deleted when computer is shut off
Cache Memory
Stores frequently used data
Passwords, usernames, etc.
ROM
Read Only Memory
Nonvolatile (permanent)

7. Outside the Box Connectors Thumbscrews: attach plug with small screws
USB Ports: Eliminates the need for specific ports for individual devices
Plug-and-play: automatically configures the system when plugged in
FireWire: similar to USB for Apple
Video Connectors
VGA (Video Graphics Array)
DVI (Digital Visual Interface)

8. Outside the Box Connectors (being replaced with USB)
Serial ports: early ports used for dial-up to create two-way communication Parallel ports: connect printers
PS/2: connect keyboards
SCSI: connect printers, scanners, cameras, etc. in a daisy chain series