Introduction to Computer Architecture. What is binary? We use the decimal (base 10) number system...
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Transcript of Introduction to Computer Architecture. What is binary? We use the decimal (base 10) number system...
Introduction to Computer Architecture
What is binary?
We use the decimal (base 10) number system
Binary is the base 2 number system Ten different numbers are used in
base 10. How many are used in base 2?
Bits & Bytes
kilo, mega, and giga are different in binary!
bit (b) – binary digit
Byte (B) – 8 binary digits
KiloByte (KB) – 210 bytes
MegaByte (MB) – 220 bytes
GigaByte (GB) – 230 bytes
Storage Scam!
Example: iPod Nano 8GB
What is computer architecture?
What does “architecture” mean? Layout and interactions of a computer
system What is a computer system? Input Process Output Can a computer system be more than
one computer? Think of an example...
Major Components of a Computer
Central Processing Unit (CPU) Random Access Memory (RAM) Hard Drive / Disk
Central Processing Unit (CPU)
Also called the “chip” or “processor”
The brain of the computer Major components:
Arithmetic Logic Unit (ALU) calculator
Control unit controls the calculator
Communication bus systems
What’s a bus?!?
Control Unit
ALU
Memory
Address Bus
Data Bus
Fetch-Execute Cycle (Machine Instruction Cycle)
1. Fetch instruction from memory
2. Decode instruction in control unit
3. Execute instruction (data may be fetched from memory)
4. Store results if necessary5. Repeat!
Control Unit
ALU
Memory
Address Bus
Data Bus
ON-OFF-ON-ON
1 0 1 1
Several ways to remember the state of a switch: Electrical – RAM, flash memory, ROM Magnetic – Hard drives, magnetic tapes Optical – CDs, DVDs
Primary Memory
Memory level CPU accesses closest RAM ~ Random Access Memory
Volatile storage (data is NOT saved when computer is off)
Used to store everything (OS, programs, etc.) while computer is on
ROM ~ Read-Only Memory Non-volatile storage Often holds the computer’s BIOS (Basic
Input/Output System) when computer first loads
What does memory look like?
Memory ~ RAM Looks like a table Address and Data Address is the location Data is the actual value Memory stores both
data and assembly instructions
Address Data
0 36
1 3765
2 786
3 356
4 252
5 67980
6 2355
7 4234
8 3466
Registers
Temporary storage containers used inside the CPU
Extremely fast MAR ~ Memory Address Register
Holds the address of where you are fetching from MDR ~ Memory Data Register
Holds the data that was fetched from memory Many other registers too (for all CPU
calculations)
Fetch-Execute Cycle (Machine Instruction Cycle)
1. Fetch instruction from memory
2. Decode instruction in control unit
3. Execute instruction (data may be fetched from memory)
4. Store results if necessary5. Repeat!
Control Unit
ALU
Memory
Address Bus
Data Bus
Fetch-Execute Animation
http://www.hartismere.com/staticvle/ictskills/FetchExecute.swf
Memory Hierarchy
Cache
Slower than registers Faster than RAM Located in front of main
RAM Different levels of cache Level1 (L1) and Level2
(L2) Size is usually around 1
MB
Virtual Memory
What if a program is too big for RAM? If a program is too big for memory
(RAM), then we start using the hard drive (disk) to store data
Prevents the computer from stalling/crashing (BUT IT IS SLOW)
Hard Drives
• Persistent storage• Non-volatile storage• Why do we need it?• Other types of persistent
storage?
CD/DVD/BluRays Lands and pits used to represent binary Optical medium - lasers and refraction used to read lands
and pits http://electronics.howstuffworks.com/cd4.htm