Assembly Lecture 1 PDF

Mansoura University Faculty of Computers and Information Department of Computer Science First Semester: 2020-2021 [CS214P] Assembly Language: An Introduction Grade: Third Year (Computer Science) Sara El-Metwally, Ph.D. Faculty of Computers and Information,...

Mansoura University Faculty of Computers and Information Department of Computer Science First Semester: 2020-2021 [CS214P] Assembly Language: An Introduction Grade: Third Year (Computer Science) Sara El-Metwally, Ph.D. Faculty of Computers and Information, Mansoura University, Egypt.  Course outlines o Course Meeting Time: Sunday, 12.20 pm – 2:00 pm o Grading : Activities Percentages Attendance (Lectures + Sections ) 5% Practical exam 15% Midterm 10% Oral 10% Final 60%  Course outlines o Course Text Book:  Course outlines o Course Labs “ materials ”:  Assignments and solving some exercises.  DosBox.  Debug Program.  Emulator 8086.  AE-TASM. o Course TA’s:  Eng. Ghada Shafiq  Course Objectives o Understand the HW of the personal computer. o Understand machine-language code and hexa- decimal format. o Understand the steps involved in assembling, linking, and executing a program. o Write programs in assembly language to handle the keyboard and screen, perform arithmetic, convert between ASCII and binary formats, perform table searches and sorts, and handle disk I/O.  Course Objectives o Trace machine execution as an aid in program debugging. o Write your own macro instructions to facilitate faster coding. o Linking separately assembled programs into one executable program.  Course Requirements Logic Design First Academic Year Computers Architecture and Organization Second Academic Year Assembly Language Third Academic Year Compilers Fourth Academic Year Microprocessors Embedded Systems  Why Assembly? (Knowledge) o Shows how program interface with operating system, processor and BIOS. o Show how data is represented and stored in memory and on external devices. o Show how processors access and execute instructions and how instructions access and process data. o Show how a program access external devices.  Why Assembly in 2019? o Programs written in assembly requires less memory and execution time. o Give programmers the flexibility to perform low level machine operations and highly technical tasks. o While most software written in high-level programming languages, a common practice is to recode in assembly those sections that are time-critical. Why Assembly in 2019? Why Assembly in 2019?  Levels of Programming o Machine language: instructions in a sequence of ones and zeros that the processor executes one at a time. o Low-level assembly language: instructions in a symbolic format designed for a specific processor and have one to one machine code. o High-level language: designed to eliminate the technicality of low level hardware details and generate many low-level instructions. Levels of Programming High-level language Compiler Low-level assembly language Assembler Machine language  What is Assembly Language? o Assembly language is a low-level programming language for a computer or other programmable device specific to a particular computer architecture. o Each personal computer has a microprocessor that manages the computer's arithmetical, logical, and control activities. o Each family of processors has its own set of instructions for handling various operations such as getting input from keyboard, displaying information on screen etc.  To Start: You need to know your Computer ? 0101 0000 0000 500H Address Word 502H Instruction LOAD 361 361H Data 2 Memory  To Start: You need to know your Computer ?  To Start: You need to know your Computer ? Word Size in bits Memory Memory size in words ( 1MB)  To Start: You need to know your Computer ? 01010110 0001 0001 0010 0010 1111 0x1122F Memory ( 1MB)  To Start: You need to know your Computer ? CPU Fetch 011100011 Decode Instruction 011100011 ADD 5,2 Execute 00000111 Memory 7  To Start: You need to know your Computer ? ALU CU Address Bus Data Bus Registers Control Bus  Intel 8086 (x86 architecture) o 16-bit registers. o 16-bit data bus. o 1 MB internal memory. o Word size = 1 byte. How many bits for address bus? 20 bits How many words can be fetched from a memory at a time? 2 words Intel 8086 (x86 architecture)  Intel 8086 (x86 architecture) 64K base system ROM 192K memory expansion area ROM BIOS data area Interrupt Vector Table  Addressing Data in Memory the Intel x86 processors use little-endian. We need to store 0529H in memory 04A27 05 04A26 29 How many words we need? -------- 2 words 00001 00000 05 29 Register Memory (Queue) (Stack)  Addressing Data in Memory o An absolute address: 20-bit value that directly references a specific location in memory. o A segment : offset address, combines the starting address of a segment with an offset value.  Addressing Data in Memory An absolute address 04A27 04A26 -------- 00001 00000 Memory (Stack)  Addressing Data in Memory 04F03 = 04F00 + 0003 04F03 04F02 04F01 Segment offset 04F00 04F00 Segment Segment start address (array) 04C00 04A00