Computer Science 101

1. Computer Science 101 Computer Systems Organization BINARY STORAGE

2. Pappaw, our puter broke.

3. What’s a man to do? Perfectly clear, huh?

4. Von Neumann Architecture • Basic Architecture of most computers • Four Major Subunits • Memory • Input-output • Arithmetic-logic unit (ALU) • Control Unit • Stored Programs

5. Von Neumann Architecture • Execution Cycle • Fetch Instruction • Decode • Execute Processor speed: 2.8GHz giga- G 10^9  1024^3 = 2^30 = 1,073,741,824Hz- cycle per second2.8 billion cycles per second

6. Bus Memory Input Output Units Control Unit ALU CPU Major Components

7. Memory (and other storage devices) • Stores: Numbers, text, programs, addresses, graphics, sound, video, etc. that are currently in use. Everything coded in some binary format. • Divided into fixed size cells (fixed number of bits). • This size is commonly 8 bits, and this 8-bit unit is called a byte. Memory: 3GB DDR3 SDRAM Hard drive: 500GB5

8. A bit is what the dentist uses to fix your byte?

9. 00100110 00111110 10100110 10101010 Memory Addresses • Each cell has an address, an unsigned integer. • All accesses to memory are via a specific address Address Cell Content 0 1 2 3

10. Capacity of a Byte • A byte contains 8 bits. How many different values can we store in a byte?00000000 0 00000001 1 00000010 2. . .11111111 255so there are 256 different values. • In general, there are 2n ways to arrange bits.

11. Capacity of a Byte • In working with popular software packages, you may have encountered situations where you were to choose values for a property, and the range of values was 0 to 255. Now you can see that the reason was that the value was being stored in a byte and that dictates the range.

12. Powerpoint

13. Basic Memory Operations • Memory Fetch • Given a specific memory address. • Retrieve the content stored at that address. • Memory Store • Given a specific memory address and • a specific value, • store the given value in the cell with the specified address.

14. 00100110 00111110 10100110 10101010 Memory Fetch Address Cell Content 2002 2003 2004 2005 Given Address: 2004 Content:

15. 00100110 00111110 10100110 10101010 Memory Fetch Address Cell Content 2002 2003 2004 2005 Given Address: 2004 Content:

16. 00100110 00111110 10100110 10101010 Memory Fetch Address Cell Content 2002 2003 2004 2005 Given Address: 2004 Content:

17. 00100110 00111110 10100110 10101010 Memory Fetch Address Cell Content 2002 2003 2004 2005 Given Address: 2004 Content:

18. 00100110 00111110 10100110 10101010 Memory Fetch Address Cell Content 2002 2003 2004 2005 Given Address: 2004 Content: 00111110

19. Address Cell Content 2002 00100110 00111110 2003 10100110 10101010 2004 2005 Given Address: 2004 Given Value: 10101010 Memory Store

20. 00100110 00111110 10100110 10101010 Memory Store Address Cell Content 2002 2003 2004 2005 Given Address: 2004 Given Value: 10101010

21. 00100110 00111110 10100110 10101010 Memory Store Address Cell Content 2002 2003 2004 2005 Given Address: 2004 Given Value: 10101010

22. 00100110 00111110 10100110 10101010 Memory Store Address Cell Content 2002 2003 2004 2005 Given Address: 2004 Given Value: 10101010

23. 00100110 10101010 10100110 10101010 Memory Store Address Cell Content 2002 2003 2004 2005 Given Address: 2004 Given Value: 10101010

24. Memory Facts and Terminology • A cell is the minimum unit of access. • Access time is same for all cells - Random Access Memory or RAM (nanoseconds - billionths of second) • ROM - Read only Memory (fetch but not store) • Some data items require more than one cell. For example, an instruction might need four cells. Note: ints require 4 cells (bytes)

25. Terminology • Storage capacity: • K  210 = 1024  Kilo as in Kb • M  220 = 1,048,576  Mega as in Mb • G  230 = 1,073,741,824  Giga as in Gb • Speed • 1  = 1 microsecond = 1 millionth of second • 1 ms = 1 millisecond = 1 thousandth of second • 1 ns = 1 nanosecond = 1 billionth of second • Cycle rate: Hertz is cycle per second

26. We have brown ones, black ones, white ones, spotted, ….