1. Computers Inside and Out
Dr Jim Martin
copyright Jim Martin 2006

2. Basics External computer parts Internal Computer parts
copyright Jim Martin 2006

3. Components inside the system unit
power supply
ports
drive bays
processor
memory
sound card
video card
Processor
Memory
Adapter cards
Sound card
Video card
Ports
Drive bays
Power supply
copyright Jim Martin 2006

4. The motherboard Main circuit board in system unit
Contains adapter cards, processor chips, and memory chips
Also called system board
copyright Jim Martin 2006

5. CPU: Central Processing Unit
Processor
Control Unit
Arithmetic Logic Unit (ALU)
Control Unit
Arithmetic Logic Unit (ALU)
Interprets and carries out basic instructions that operate a computer
Instructions Data Information
Control unit directs and coordinates operations in computer
Memory
Input Devices
Data
Information
Output Devices
Arithmetic logic unit (ALU) performs arithmetic, comparison, and logical operations
Instructions Data Information
Also called the processor
Storage Devices
copyright Jim Martin 2006

6. Machine Cycle Four operations of the CPU comprise a machine cycle
Step 1. Fetch Obtain program instruction or data item from memory
Processor
Control Unit
Memory
ALU
Step 2. Decode Translate instruction into commands
Step 4. Store Write result to memory
Step 3. Execute Carry out command
copyright Jim Martin 2006

7. Each tick is a clock cycle Pace of system clock is clock speed
Controls timing of all computer operations
Generates regular electronic pulses, or ticks, that set operating pace of components of system unit
Each tick is a clock cycle
Pace of system clock is clock speed
Most clock speeds are in the gigahertz (GHz) range (1 GHz = one billion ticks of system clock per second)
Processor speed can also be measured in millions of instructions per second (MIPS)
copyright Jim Martin 2006

8. Which Processor ?
Celeron
Itanium or Xeon
Pentium family
1.3 GHz and up
3.0 GHz and up
2.4 GHz to 3.0 GHz
Up to 2.4 GHz
2.2 GHz and up
Intel Processor Desired Clock Speed
The faster the processor, the more expensive the computer
The faster the processor, the more electricity consumers….this is why processors for laptops run at slower system clock speeds
copyright Jim Martin 2006

9. Data Representation Computers are digital which means:
Recognize only two discrete states: on or off
Use a binary system to recognize two states
Use Number system with two unique digits: 0 and 1, called bits (short for binary digits)
copyright Jim Martin 2006

10. Bits/Bytes
Computers speak in terms of 1’s and 0’s (i.e., in binary!!!)
When one computer sends the message ‘Hello’ to another computer, each of the 5 characters is represented as a sequence of 8 bits
A bit is a single 1 or 0
A byte is a sequence of bits- usually 8
The message ‘Hello’ is stored on the computer in 5 bytes
Characters (e.g., “A”) are mapped to unique sequences of 8 bits
This mapping is defined by a standard known as ASCII
copyright Jim Martin 2006

11. Binary number system
In a base-10 number system, the values of each digit range from 0 … 9.
But the magnitude of each digit is a multiple of 10: (the 1’s column, the 10’s column, 100, 1000… )
the pattern: 10EXP(column #)
E.g., the decimal number 1023 :
1* * *10 + 3*1 = 1023
Binary numbers are a number system made up of 0's and 1's
Each digit can only be a 0 or 1.
The magnitude of each column is 2EXP(column #)
The values of the first 8 places in binary notation are (highest to lowest):
Bit#
We show several numbers in binary (with 8 bits or digits) and in decimal
= 2 in decimal
= 8 in decimal
= 130 in decimal
= 255 in decimal
How would you write the number 3 in binary?
copyright Jim Martin 2006

12. Homework for next time Complete the 3 worksheets
copyright Jim Martin 2006