1. COMPUTER ORGANIZATIONS CSNB123 May 2014Systems and Networking1

2. COMPUTER ORGANIZATIONS CSNB123 Expected Course Outcome #Course OutcomeCoverage 1Explain the concepts that underlie modern computer architecture, its evolution, functions and organization.  2Identify the best organization of a computer for achieving the best performance when asked to make a selection from the current market. 3Demonstrate the flow of an instruction cycle. 4Differentiate types of memory components in terms of its technology and usage.  5Convert integer and floating point numbers to its internal data representation.  6Construct a series of computer instructions to perform low-level processor operations. 7Explain the RISC and CISC computers, and single core and multi-core computers May2014Systems and Networking2

3. COMPUTER ORGANIZATIONS CSNB123 Overview Arithmetic Logic Unit (ALU) Focus on – computer arithmetic Logic function Support 2 types of number Integer Floating-point Component in processor May 2014Systems and Networking3

4. COMPUTER ORGANIZATIONS CSNB123 ALU Part of the computer that do the arithmetic and logical operation on data Simple digital logic devices that can;  Store binary digits  Perform simple BOOLEAN logic operations May 2014Systems and Networking4 CPU Arithmetic Logic Unit (ALU) Registers Control Unit Internal CPU Interconnection

5. COMPUTER ORGANIZATIONS CSNB123 ALU Interconnection May 2014Systems and Networking5

6. COMPUTER ORGANIZATIONS CSNB123 ALU and Registers ComponentDescription Registers Present data to ALU Store result of an operation Temporary storage locations within the processor that are connected by signal paths to the ALU ALU set flags – result of an operation – store in registers Control unitProvides signals that control; Operation of the ALU Movement of the data into and out of the ALU May 2014Systems and Networking6 CPU Arithmetic Logic Unit (ALU) Registers Control Unit Internal CPU Interconnection

7. COMPUTER ORGANIZATIONS CSNB123 Integer Representation Computer - logic circuits - operate on information; 0 and 1  two values electrical signals – bit How to represent negative value in binary?  Sign-magnitude representation  Twos complements representation May 2014Systems and Networking7

8. COMPUTER ORGANIZATIONS CSNB123 May 2014Systems and Networking8

9. COMPUTER ORGANIZATIONS CSNB123 Sign-magnitude Representation Ways of presenting -ve and +ve integers The most significant (leftmost) bits in the word as a sign bit Example: if the sign bit is 0 then the number is +ve, vice versa Hence sign magnitude representation employed sign bit May 2014Systems and Networking9

10. COMPUTER ORGANIZATIONS CSNB123 Sign-magnitude Representation (Cont.) Example +18 = 00010010 -18 =10010010 Rarely used Drawbacks;  Addition/subtraction require a consideration of both the signs of the numbers and their relative magnitudes to carry out the required operation  2 representation of 0; +0 10 = 00000000 -0 10 = 10000000 May 2014Systems and Networking10

11. COMPUTER ORGANIZATIONS CSNB123 May 2014Systems and Networking11

12. COMPUTER ORGANIZATIONS CSNB123 Twos Complements Representation Used the most significant bit (MSB) as a sign bit (similar to sign magnitude) Differs – the other bits are interpreted Example: +3 = 00000011 +2 = 00000010 +1 = 00000001 +0 = 00000000 May 2014Systems and Networking12

13. COMPUTER ORGANIZATIONS CSNB123 Twos Complements Representation (Cont.) Negative – sign bit = 1 Example:  -1 = 11111111  -2 = 11111110  -3 = 11111101 May 2014Systems and Networking13

14. COMPUTER ORGANIZATIONS CSNB123 Twos Complements Representation (Cont.) Steps for negative integers. Example: -3 May 2014Systems and Networking14

15. COMPUTER ORGANIZATIONS CSNB123 Twos Complements Representation (Cont.) Example: 11110000 May 2014Systems and Networking15

16. COMPUTER ORGANIZATIONS CSNB123 Twos Complements Representation – Special Case Example: 0, consider an 8-bit representation May 2014Systems and Networking16

17. COMPUTER ORGANIZATIONS CSNB123 Twos Complements Representation – Range of Numbers 8-bit 2s complement +127 = 0111 1111 -127 = 1000 0000 16-bit 2s complement +32767 = 01111111 11111111 -32767 = 10000000 00000000 May 2014Systems and Networking17

18. COMPUTER ORGANIZATIONS CSNB123 Twos Complements Representation – Conversion between lengths Positive Pack with leading zeros 8-bits  +18 = 00010010 16-bits  -18 = 00000000 00010010 Negative Pack with leading ones 8-bits  +18 = 11101110 16-bits  -18 = 11111111 11101110 May 2014Systems and Networking18

19. COMPUTER ORGANIZATIONS CSNB123 Twos Complements Representation - Operations Addition Subtraction May 2014Systems and Networking19

20. COMPUTER ORGANIZATIONS CSNB123 Twos Complements Representation - Operations Addition Addition follows as if the two numbers were unsigned integers (positive or zero) Overflow – result is larger than word  ALU provide signals May 2014Systems and Networking20

21. COMPUTER ORGANIZATIONS CSNB123 Twos Complements Representation - Operations Subtraction Do subtraction via addition May 2014Systems and Networking21

22. COMPUTER ORGANIZATIONS CSNB123 Twos Complements Representation - Operations OVERFLOW RULE May 2014Systems and Networking22

23. COMPUTER ORGANIZATIONS CSNB123 Additional Reference William Stallings, Computer Organization and Architecture: Designing for Performance, 8th. Edition, Prentice-Hall Inc., 2010 May2014Systems and Networking23

24. COMPUTER ORGANIZATIONS CSNB123 May2014Systems and Networking24 This teaching material is belongs to Systems and Networking Department College of Information Technology Universiti Tenaga Nasional (UNITEN) Malaysia 2014