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Assembly Language for Intel-Based Computers, 5th Edition Kip Irvine Chapter 1: Basic Concepts Slides prepared by the author Revision date: June 3, 2006 (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. Printing this Slide Show To print this slide show with black characters on a white background, do the following: •Select Print... from the File menu. •Select Handouts in the Print what drop-down box. •Select 2 or 3 in the Slides per page drop-down box. •Select the Pure black and white check box (optional) •Click on OK to begin printing. Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. Web site Examples 2 Chapter 1 Overview • 1.1 Welcome to Assembly Language • 1.2 Virtual Machine Concept • 1.3 Data Representation • 1.4 Boolean Operations Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. Web site Examples 3 1.1 Welcome to Assembly Language • 1.1.1 Some Good Questions to Ask • 1.1.2 Assembly Language Applications Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. Web site Examples 4 2.1.1 Questions to Ask • 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. Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. Web site Examples 5 2.1.1 Questions to Ask (cont) • What hardware/software do I need? • A computer with an Intel386, Intel486 or one of the Pentium processors (IA-32 processor family) • OS: Microsoft Windows, MS-DOS, LINUX running a DOS emulator • Editor • Assembler • Linker (Microsoft 16-bit linker: LINK.EXE, 32-bit linker: LINK32.EXE), • Debugger (16-bit MS-DOS programs: MASM CodeView, TASM Turbo Debugger. 32-bit Windows console programs: Microsoft Visual Studio –msdev.exe • What types of programs will I create? • 16-Bit Real-Address Mode: MS-DOS, DOS emulator • 32-Bit Protected Mode: Microsoft Windows Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. Web site Examples 6 2.1.1 Questions to Ask (cont) • 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 • 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 Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. Web site Examples 7 2.1.1 Questions to Ask (cont) • 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 Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. Web site Examples 8 1.1.2 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) Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. Web site Examples 9 Comparing ASM to High-Level Languages Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. Web site Examples 10 Chapter 1 Overview: What’ s Next • 1.1 Welcome to Assembly Language • 1.2 Virtual Machine Concept • 1.3 Data Representation • 1.4 Boolean Operations Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. Web site Examples 11 1.2 Virtual Machine Concept • Virtual Machines • Specific Machine Levels Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. Web site Examples 12 1.2 Virtual Machines • Virtual machine concept • In terms of programming Language : • 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 Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. Web site Examples 13 1.2 Virtual Machines (Cont.) • 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 Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. Web site Examples 14 Translating Languages English: Display the sum of A times B plus C. C++: cout << (A * B + C); Assembly Language: Intel Machine Language: mov eax,A mul B add eax,C call WriteInt A1 00000000 F7 25 00000004 03 05 00000008 E8 00500000 Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. Web site Examples 15 Specific Machine Levels High-Level Language Level 5 Assembly Language Level 4 Operating System Level 3 Instruction Set Architecture Level 2 Microarchitecture Level 1 Digital Logic Level 0 Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. (descriptions of individual levels follow . . . ) Web site Examples 16 Digital Logic • Level 0 • CPU, constructed from digital logic gates • System bus • Memory • Implemented using bipolar transistors next: Data Representation Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. Web site Examples 17 Microarchitecture • Level 1 • Interprets conventional machine instructions (Level 2) • Executed by digital hardware (Level 0) Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. Web site Examples 18 Instruction Set Architecture • Level 2 • Also known as conventional machine language • Executed by Level 1 (microarchitecture) program •Each machine-language instruction is executed by several microinstructions Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. Web site Examples 19 Operating System • Level 3 • Provides services to Level 4 programs • Translated and run at the instruction set architecture level (Level 2) Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. Web site Examples 20 Assembly Language • Level 4 • Instruction mnemonics such as ADD, SUB and MOV that are easily translated to the instruction set architecture level (Level 2) • Calls functions written at the operating system level (Level 3) • Programs are translated into machine language (Level 2) Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. Web site Examples 21 High-Level Language • Level 5 • Application-oriented languages •C++, Java, Pascal, Visual Basic . . . • Programs compile into assembly language (Level 4) Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. Web site Examples 22 Chapter 1 Overview: What’ s Next • 1.1 Welcome to Assembly Language • 1.2 Virtual Machine Concept • 1.3 Data Representation • 1.4 Boolean Operations Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. Web site Examples 23 1.3 Data Representation • 1.3.1 Binary Numbers •Translating between binary and decimal • 1.3.2 Binary Addition • 1.3.3 Integer Storage Sizes • 1.3.4 Hexadecimal Integers •Translating between decimal and hexadecimal •Hexadecimal subtraction • 1.3.5 Signed Integers •Binary subtraction • 1.3.6 Character Storage Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. Web site Examples 24 1.3.1 Binary Numbers • Digits are 1 and 0 •1 = true •0 = false • MSB –most significant bit • LSB –least significant bit MSB • Bit numbering: LSB 1011001010011100 15 Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. 0 Web site Examples 25 Binary Numbers (cont.) • Each digit (bit) is either 1 or 0 • Each bit represents a power of 2: 1 1 1 1 1 1 1 1 27 26 25 24 23 22 21 20 Every binary number is a sum of powers of 2 Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. Web site Examples 26 Translating Binary to Decimal Weighted positional notation shows how to calculate the decimal value of each binary bit: dec = (Dn-1 2n-1) (Dn-2 2n-2) ... (D1 21) (D0 20) D = binary digit binary 00001001 = decimal 9: (1 23) + (1 20) = 9 Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. Web site Examples 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 Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. Web site Examples 28 1.3.2 Binary Addition • Starting with the LSB, add each pair of digits, include the carry if present. + bit position: carry: 1 0 0 0 0 0 1 0 0 (4) 0 0 0 0 0 1 1 1 (7) 0 0 0 0 1 0 1 1 (11) 7 6 5 4 3 2 1 0 Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. Web site Examples 29 1.3.3 Integer Storage Sizes byte Standard sizes: word doubleword quadword 8 16 32 64 What is the largest unsigned integer that may be stored in 20 bits? Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. Web site Examples 30 1.3.4 Hexadecimal Integers Binary values are represented in hexadecimal. Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. Web site Examples 31 Translating Binary to Hexadecimal •Each hexadecimal digit corresponds to 4 binary bits. •Example: Translate the binary integer 000101101010011110010100 to hexadecimal: Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. Web site Examples 32 Converting Hexadecimal to Decimal • Multiply each digit by its corresponding power of 16: dec = (D3 163) + (D2 162) + (D1 161) + (D0 160) • Hex 1234 equals (1 163) + (2 162) + (3 161) + (4 160), or decimal 4,660. • Hex 3BA4 equals (3 163) + (11 * 162) + (10 161) + (4 160), or decimal 15,268. Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. Web site Examples 33 Powers of 16 Used when calculating hexadecimal values up to 8 digits long: Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. Web site Examples 34 Converting Decimal to Hexadecimal decimal 422 = 1A6 hexadecimal Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. Web site Examples 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. 36 42 78 28 45 6D 1 1 28 58 80 6A 4B B5 21 / 16 = 1, rem 5 Important skill: Programmers frequently add and subtract the addresses of variables and instructions. Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. Web site Examples 36 Hexadecimal Subtraction • When a borrow is required from the digit to the left, add 16 (decimal) to the current digit's value: 16 + 5 = 21 1 C6 A2 24 75 47 2E Practice: The address of var1 is 00400020. The address of the next variable after var1 is 0040006A. How many bytes are used by var1? Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. Web site Examples 37 1.3.5 Signed Integers The highest bit indicates the sign. 1 = negative, 0 = positive sign bit 1 1 1 1 0 1 1 0 0 0 0 0 1 0 1 0 Negative Positive If the highest digit of a hexadecimal integer is > 7, the value is negative. Examples: 8A, C5, A2, 9D Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. Web site Examples 38 Forming the Two's Complement • Negative numbers are stored in two's complement notation • Represents the additive Inverse Note that 00000001 + 11111111 = 00000000 Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. Web site Examples 39 Binary Subtraction • When subtracting A –B, convert B to its two's complement • Add A to (–B) 00001100 –0 0 0 0 0 0 1 1 00001100 11111101 00001001 Practice: Subtract 0101 from 1001. Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. Web site Examples 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 Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. Web site Examples 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? Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. Web site Examples 42 1.3.6 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 Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. Web site Examples 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: "9C" next: Boolean Operations Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. Web site Examples 44 Chapter 1 Overview: What's Next • 1.1 Welcome to Assembly Language • 1.2 Virtual Machine Concept • 1.3 Data Representation • 1.4 Boolean Operations Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. Web site Examples 45 1.4 Boolean Operations • NOT • AND • OR • Operator Precedence • Truth Tables Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. Web site Examples 46 Boolean Algebra • Based on symbolic logic, designed by George Boole • Boolean expressions created from: •NOT, AND, OR Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. Web site Examples 47 NOT • Inverts (reverses) a boolean value • Truth table for Boolean NOT operator: Digital gate diagram for NOT: NOT Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. Web site Examples 48 AND • Truth table for Boolean AND operator: Digital gate diagram for AND: AND Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. Web site Examples 49 OR • Truth table for Boolean OR operator: Digital gate diagram for OR: OR Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. Web site Examples 50 Operator Precedence • Examples showing the order of operations: Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. Web site Examples 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 Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. Web site Examples 52 Truth Tables (2 of 3) • Example: X Y Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. Web site Examples 53 Truth Tables (3 of 3) • Example: (Y S) (X S) S X mux Z Y Two-input multiplexer Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. Web site Examples 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 Irvine, Kip R. Assembly Language for Intel-Based Computers 5/e, 2007. Web site Examples 55