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# Intro comparch

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### Intro comparch

1. 1. Introduction to Computer Architecture<br />Lecture :- 1<br />Date :- 15/02/11<br />Designed by :- Er Sanjay Agal<br />
2. 2. What is binary?<br />We use the decimal (base 10) number system<br />Binary is the base 2 number system<br />Ten different numbers are used in base 10. How many are used in base 2?<br />Designed by Sanjay Agal<br />
3. 3. Bits & Bytes<br />kilo, mega, and giga are different in binary!<br />bit (b) – binary digit<br />Byte (B) – 8 binary digits<br />KiloByte (KB) – 210 bytes<br />MegaByte (MB) – 220 bytes<br />GigaByte (GB) – 230 bytes<br />Designed by Sanjay Agal<br />
4. 4. Storage Scam!<br />Example: iPod Nano 8GB<br />Designed by Sanjay Agal<br />
5. 5. What is computer architecture?<br />What does “architecture” mean?<br />Layout and interactions of a computer system<br />What is a computer system?<br />Input  Process  Output<br />Can a computer system be more than one computer? Think of an example...<br />Designed by Sanjay Agal<br />
6. 6. Major Components of a Computer<br />Central Processing Unit (CPU)<br />Random Access Memory (RAM)<br />Hard Drive / Disk<br />Designed by Sanjay Agal<br />
7. 7. ON-OFF-ON-ON<br /> 1 0 1 1<br />Several ways to remember the state of a switch:<br />Electrical – RAM, flash memory<br />Magnetic – Hard drives, magnetic tapes<br />Optical – CDs, DVDs<br />Designed by Sanjay Agal<br />
8. 8. What does memory look like?<br />Memory ~ RAM<br />Looks like a table<br />Address and Data<br />Address is the location<br />Data is the actual value<br />Memory stores both data and assembly instructions<br />Designed by Sanjay Agal<br />
9. 9. Central Processing Unit (CPU)<br />Also called the “chip” or “processor”<br />The brain of the computer<br />Major components:<br />Arithmetic Logic Unit (ALU)<br />calculator<br />Control unit<br />controls the calculator<br />Communication bus systems<br />What’s a bus?!?<br />Address Bus<br />Control Unit<br />Memory<br />ALU<br />Data Bus<br />Designed by Sanjay Agal<br />
10. 10. Fetch-Execute Cycle<br />Fetch instruction from memory<br />Decode instruction in control unit<br />Execute instruction (data may be fetched from memory)<br />Store results if necessary<br />Repeat!<br />Address Bus<br />Control Unit<br />Memory<br />ALU<br />Data Bus<br />Designed by Sanjay Agal<br />
11. 11. Registers<br />Temporary storage containers used inside the CPU<br />Extremely fast<br />Fixed size, usually multiples of 8-bits<br />Also called a “word”<br />Example: 32-bit machines (4-byte words)<br />How large is a word in a 64-bit machine?<br />Designed by Sanjay Agal<br />
12. 12. Cache<br />Slower than registers<br />Faster than RAM<br />Located in front of main RAM<br />Different levels of cache<br />Level1 (L1) and Level2 (L2)<br />Size is usually around 1 MB<br />Designed by Sanjay Agal<br />
13. 13. Memory Hierarchy<br />Designed by Sanjay Agal<br />
14. 14. Virtual Memory<br />What if a program is too big for RAM?<br />If a program is too big for memory (RAM), then we start using the hard drive (disk) to store data<br />Designed by Sanjay Agal<br />
15. 15. Hard Drives<br />Designed by Sanjay Agal<br />
16. 16. CD/DVDs<br />Lands and pits used to represent binary<br />Optical medium - lasers and refraction used to read lands and pits<br />Designed by Sanjay Agal<br />
17. 17. Direct Access<br />also known as “random access”<br />No need to go through other data to get the data you want<br />We already know where the data is, so we just get it<br />“Magic data retrieval” – no movement/motion<br />Example: registers, cache, RAM<br />Designed by Sanjay Agal<br />
18. 18. Sequential Access<br />also known as “serial-access”<br />Data is ordered in some sequential fashion<br />To get to your data, you need to go through other data in front of it<br />Example: <br />Fast-forwarding through a tape to get to the song you want<br />Designed by Sanjay Agal<br />
19. 19. Direct-Access vs. Sequential Access<br />Direct-Access:<br />Advantage: fast access<br />Disadvantage: data cannot be accessed in sequential or sorted order<br />Data is placed randomly on the disk<br />Accessing things in order then requires an index file<br />Slower when trying to access sequential data that is not already in order (back-and-forth-and-back-and-forth)<br />Example: hard drives (disks)<br />Sequential Access<br />Advantage: Simple to organize (already in some sequential order)<br />Disadvantage: Slow when accessing specific things in no order<br />Example: magnetic tape backups<br />Could we implement sequential access using a hard disk?<br />Designed by Sanjay Agal<br />