1. Assembly Language for Intel-Based Computers, 5 th Edition Chapter 1: Basic Concepts (c) Pearson Education, 2006-2007. All rights reserved. You may modify and copy this slide show for your personal use, or for use in the classroom, as long as this copyright statement, the author's name, and the title are not changed. Kip Irvine

2. Web siteWeb site ExamplesExamples Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. 2 Chapter Overview Welcome to Assembly Language Virtual Machine Concept Data Representation Boolean Operations

3. Web siteWeb site ExamplesExamples Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. 3 Welcome to Assembly Language Assembly language is the oldest programming language. Of all languages, it bears the closest resemblance to the native language of a computer. Direct access to a computer’s hardware To understand a great deal about your computer’s architecture and operating system

4. Web siteWeb site ExamplesExamples Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. 4 Some Good Questions to Ask [1/4] What background should I have? Computer programming (C++, C#, JAVA, VB…) What is an assembler? A program that converts source-code programs from assembly language into machine language MASM (Microsoft Assembler), TASM (Borland Turbo Assembler) Linker (a companion program of Assembler) combines individual files created by an assembler into a single executable program. Debugger provides a way for a programmer to trace the execution of a program and examine the contents of memory.

5. Web siteWeb site ExamplesExamples Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. 5 Some Good Questions to Ask [2/4] What types of programs will I create? 16-Bit Real-Address Mode: MS-DOS, DOS emulator 32-Bit Protected Mode: Microsoft Windows How does assembly language (AL) relate to machine language? One-to-one relationship How do C++ and Java relate to AL? E.g., X=(Y+4) *3 mov eax, Y add eax, 4 mov ebx, 3 imul ebx mov X, eax

6. Web siteWeb site ExamplesExamples Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. 6 Some Good Questions to Ask [3/4] What will I learn? Basic principles of computer architecture Basic Boolean logic How IA-32 processors manage memory, using real mode, protected mode and virtual mode How high-level language compilers (such as C++) translate statements into assembly language and native machine code Improvement of the machine-level debugging skills (e.g., errors due to memory allocation) How application programs communicate with the computer’s operating system via interrupt handlers, system calls, and common memory areas

7. Web siteWeb site ExamplesExamples Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. 7 Some Good Questions to Ask [4/4] Is AL portable? A language whose source program can be compiled and run on a wide variety of computer systems is said to be portable. AL makes no attempt to be portable. It is tied to a specific processor family. Why learn AL? Embedded system programs Programs to be highly optimized for both space and runtime speed To gain an overall understanding of the interaction between the hardware, OS and application programs Device driver: programs that translate general operating system commands into specific references to hardware details

8. Web siteWeb site ExamplesExamples Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. 8 Assembly Language Applications Some representative types of applications: Business application for single platform Hardware device driver Business application for multiple platforms Embedded systems & computer games (see next panel)

9. Web siteWeb site ExamplesExamples Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. 9 Comparing ASM to High-Level Languages

10. Web siteWeb site ExamplesExamples Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. 10 What's Next Welcome to Assembly Language Virtual Machine Concept Data Representation Boolean Operations

11. Web siteWeb site ExamplesExamples Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. 11 Virtual Machine Concept Virtual Machines Specific Machine Levels

12. Web siteWeb site ExamplesExamples Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. 12 Virtual Machines Virtual Machines [1/2] Virtual machine concept A most effective way to explain how a computer’s hardware and software are related In terms of programming languages Each computer has a native machine language (language L0) that runs directly on its hardware A more human-friendly language is usually constructed above machine language, called Language L1 Programs written in L1 can run two different ways: Interpretation – L0 program interprets and executes L1 instructions one by one Translation – L1 program is completely translated into an L0 program, which then runs on the computer hardware

13. Web siteWeb site ExamplesExamples Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. 13 Virtual Machines Virtual Machines [2/2] In terms of a hypothetical computer VM1 can execute commands written in language L1. VM2 can execute commands written in language L2. The process can repeat until a virtual machine VMn can be designed that supports a powerful, easy-to-use language. The Java programming language is based on the virtual machine concept. A program written in the Java language is translated by a Java compiler into Java byte code. Java byte code: a low-level language that is quickly executed at run time by Java virtual machine (JVM). The JVM has been implemented on many different computer systems, making Java programs relatively system-independent.

14. Web siteWeb site ExamplesExamples Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. 14 Translating Languages English: Display the sum of A times B plus C. C++: cout << (A * B + C); Assembly Language: mov eax,A mul B add eax,C call WriteInt Intel Machine Language: A1 00000000 F7 25 00000004 03 05 00000008 E8 00500000

15. Web siteWeb site ExamplesExamples Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. 15 Specific Machine Levels (descriptions of individual levels follow... )

16. Web siteWeb site ExamplesExamples Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. 16 High-Level Language Level 5 Application-oriented languages C++, Java, Pascal, Visual Basic... Programs compile into assembly language (Level 4)

17. Web siteWeb site ExamplesExamples Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. 17 Assembly Language Level 4 Instruction mnemonics that have a one-to- one correspondence to machine language Calls functions written at the operating system level (Level 3) Programs are translated into machine language (Level 2)

18. Web siteWeb site ExamplesExamples Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. 18 Operating System Level 3 Provides services to Level 4 programs Translated and run at the instruction set architecture level (Level 2)

19. Web siteWeb site ExamplesExamples Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. 19 Instruction Set Architecture Level 2 Also known as conventional machine language Executed by Level 1 (microarchitecture) program

20. Web siteWeb site ExamplesExamples Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. 20 Microarchitecture Level 1 Interprets conventional machine instructions (Level 2) Executed by digital hardware (Level 0)

21. Web siteWeb site ExamplesExamples Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. 21 Digital Logic Level 0 CPU, constructed from digital logic gates System bus Memory Implemented using bipolar transistors next: Data Representation

22. Web siteWeb site ExamplesExamples Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. 22 What's Next Welcome to Assembly Language Virtual Machine Concept Data Representation Boolean Operations

23. Web siteWeb site ExamplesExamples Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. 23 Data Representation Binary Numbers Translating between binary and decimal Binary Addition Integer Storage Sizes Hexadecimal Integers Translating between decimal and hexadecimal Hexadecimal subtraction Signed Integers Binary subtraction Character Storage

24. Web siteWeb site ExamplesExamples Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. 24 Binary Numbers Digits are 1 and 0 1 = true 0 = false MSB – most significant bit LSB – least significant bit Bit numbering:

25. Web siteWeb site ExamplesExamples Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. 25 Binary Numbers Each digit (bit) is either 1 or 0 Each bit represents a power of 2: Every binary number is a sum of powers of 2

26. Web siteWeb site ExamplesExamples Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. 26 Translating Binary to Decimal Weighted positional notation shows how to calculate the decimal value of each binary bit: dec = (D n-1  2 n-1 )  (D n-2  2 n-2 ) ...  (D 1  2 1 )  (D 0  2 0 ) D = binary digit binary 00001001 = decimal 9: (1  2 3 ) + (1  2 0 ) = 9

27. Web siteWeb site ExamplesExamples Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. 27 Translating Unsigned Decimal to Binary Repeatedly divide the decimal integer by 2. Each remainder is a binary digit in the translated value: 37 = 100101

28. Web siteWeb site ExamplesExamples Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. 28 Binary Addition Starting with the LSB, add each pair of digits, include the carry if present.

29. Web siteWeb site ExamplesExamples Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. 29 Integer Storage Sizes What is the largest unsigned integer that may be stored in 20 bits? Standard sizes:

30. Web siteWeb site ExamplesExamples Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. 30 Hexadecimal Integers Binary values are represented in hexadecimal.

31. Web siteWeb site ExamplesExamples Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. 31 Translating Binary to Hexadecimal Each hexadecimal digit corresponds to 4 binary bits. Example: Translate the binary integer 000101101010011110010100 to hexadecimal:

32. Web siteWeb site ExamplesExamples Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. 32 Converting Hexadecimal to Decimal Multiply each digit by its corresponding power of 16: dec = (D 3  16 3 ) + (D 2  16 2 ) + (D 1  16 1 ) + (D 0  16 0 ) Hex 1234 equals (1  16 3 ) + (2  16 2 ) + (3  16 1 ) + (4  16 0 ), or decimal 4,660. Hex 3BA4 equals (3  16 3 ) + (11 * 16 2 ) + (10  16 1 ) + (4  16 0 ), or decimal 15,268.

33. Web siteWeb site ExamplesExamples Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. 33 Powers of 16 Used when calculating hexadecimal values up to 8 digits long:

34. Web siteWeb site ExamplesExamples Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. 34 Converting Decimal to Hexadecimal decimal 422 = 1A6 hexadecimal

35. Web siteWeb site ExamplesExamples Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. 35 Hexadecimal Addition Divide the sum of two digits by the number base (16). The quotient becomes the carry value, and the remainder is the sum digit. 3628286A 4245584B 786D80B5 1 1 21 / 16 = 1, rem 5 Important skill: Programmers frequently add and subtract the addresses of variables and instructions.

36. Web siteWeb site ExamplesExamples Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. 36 Hexadecimal Subtraction When a borrow is required from the digit to the left, add 16 (decimal) to the current digit's value: C675 A247 242E 11 16 + 5 = 21 Practice: The address of var1 is 00400020. The address of the next variable after var1 is 0040006A. How many bytes are used by var1?

37. Web siteWeb site ExamplesExamples Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. 37 Signed Integers The highest bit indicates the sign. 1 = negative, 0 = positive If the highest digit of a hexadecimal integer is > 7, the value is negative. Examples: 8A, C5, A2, 9D

38. Web siteWeb site ExamplesExamples Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. 38 Forming the Two's Complement Negative numbers are stored in two's complement notation Represents the additive Inverse Note that 00000001 + 11111111 = 00000000

39. Web siteWeb site ExamplesExamples Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. 39 Binary Subtraction When subtracting A – B, convert B to its two's complement Add A to (–B)0 0 0 0 1 1 0 0 –0 0 0 0 0 0 1 11 1 1 1 1 1 0 1 0 0 0 0 1 0 0 1 Practice: Subtract 0101 from 1001.

40. Web siteWeb site ExamplesExamples Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. 40 Learn How To Do the Following: Form the two's complement of a hexadecimal integer Convert signed binary to decimal Convert signed decimal to binary Convert signed decimal to hexadecimal Convert signed hexadecimal to decimal

41. Web siteWeb site ExamplesExamples Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. 41 Ranges of Signed Integers The highest bit is reserved for the sign. This limits the range: Practice: What is the largest positive value that may be stored in 20 bits?

42. Web siteWeb site ExamplesExamples Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. 42 Character Storage Character sets Standard ASCII(0 – 127) Extended ASCII (0 – 255) ANSI (0 – 255) Unicode (0 – 65,535) Null-terminated String Array of characters followed by a null byte Using the ASCII table back inside cover of book

43. Web siteWeb site ExamplesExamples Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. 43 Numeric Data Representation pure binary can be calculated directly ASCII binary string of digits: "01010101" ASCII decimal string of digits: "65" ASCII hexadecimal string of digits: “41" next: Boolean Operations

44. Web siteWeb site ExamplesExamples Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. 44 What's Next Welcome to Assembly Language Virtual Machine Concept Data Representation Boolean Operations

45. Web siteWeb site ExamplesExamples Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. 45 Boolean Operations NOT AND OR Operator Precedence Truth Tables

46. Web siteWeb site ExamplesExamples Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. 46 Boolean Algebra Based on symbolic logic, designed by George Boole Boolean expressions created from: NOT, AND, OR

47. Web siteWeb site ExamplesExamples Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. 47 NOT Inverts (reverses) a boolean value Truth table for Boolean NOT operator: Digital gate diagram for NOT:

48. Web siteWeb site ExamplesExamples Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. 48 AND Truth table for Boolean AND operator: Digital gate diagram for AND:

49. Web siteWeb site ExamplesExamples Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. 49 OR Truth table for Boolean OR operator: Digital gate diagram for OR:

50. Web siteWeb site ExamplesExamples Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. 50 Operator Precedence Examples showing the order of operations:

51. Web siteWeb site ExamplesExamples Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. 51 Truth Tables (1 of 3) A Boolean function has one or more Boolean inputs, and returns a single Boolean output. A truth table shows all the inputs and outputs of a Boolean function Example:  X  Y

52. Web siteWeb site ExamplesExamples Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. 52 Truth Tables (2 of 3) Example: X   Y

53. Web siteWeb site ExamplesExamples Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. 53 Truth Tables (3 of 3) Example: (Y  S)  (X   S) Two-input multiplexer

54. Web siteWeb site ExamplesExamples Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. 54 Summary Assembly language helps you learn how software is constructed at the lowest levels Assembly language has a one-to-one relationship with machine language Each layer in a computer's architecture is an abstraction of a machine layers can be hardware or software Boolean expressions are essential to the design of computer hardware and software

55. Web siteWeb site ExamplesExamples Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. 55 54 68 65 20 45 6E 64 What do these numbers represent?