Assembly Language and Machine Code
22 Questions
0 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the primary function of an assembler?

  • To compare two machine codes
  • To convert assembly programs into machine code (correct)
  • To compile high-level languages directly to machine code
  • To translate assembly code into human-readable format

    • Which file extensions are commonly associated with machine code?

  • .obj and .exe (correct)
  • .c and .java
  • .py and .rb
  • .asm and .hex

    • In terms of readability, how does assembly language improve upon machine code?

  • It provides symbolic representations of CPU instructions. (correct)
  • It eliminates the need for any specific syntax.
  • It uses higher-level programming constructs.
  • It automatically debugs the code.

    • What role does a compiler play in programming?

    <p>It translates high-level language into assembly or machine code.</p> Signup and view all the answers

    Which of the following statements is true regarding program faults?

    <p>Program faults due to compiler behavior can be difficult to work around.</p> Signup and view all the answers

    How are high-level languages typically represented in the programming hierarchy?

    <p>They are transformed into assembly language.</p> Signup and view all the answers

    What is a common issue faced by compiler implementers?

    <p>The difficulty in tracking down incorrect compiler behavior.</p> Signup and view all the answers

    Which type of code is executed directly by the CPU?

    <p>Machine code</p> Signup and view all the answers

    What is represented by Rd in the instruction format?

    <p>The destination register</p> Signup and view all the answers

    In the instruction format, what does Operand2 signify?

    <p>A flexible second register or an immediate value</p> Signup and view all the answers

    How is the condition part of the instruction format denoted?

    <p>By an optional two-letter condition</p> Signup and view all the answers

    Given the instruction ADD R3, R2, R1, what does R3 represent?

    <p>The destination register</p> Signup and view all the answers

    What does the 'S' flag indicate in the instruction format?

    <p>It indicates a specific processor status after execution</p> Signup and view all the answers

    In the context of ARM assembly, what is the significance of the 'MOV' instruction?

    <p>It moves data from one location to another</p> Signup and view all the answers

    Which of the following is true regarding Operand2?

    <p>It can be a register or an immediate value</p> Signup and view all the answers

    How many bits are typically used for the opcode in the instruction format?

    <p>12 bits</p> Signup and view all the answers

    What does the instruction 'ADD R3, R2, R1' compute?

    <p>Adds the values in R2 and R1, storing the result in R3</p> Signup and view all the answers

    What is required if no Rn is specified in an instruction?

    <p>Rn is set to 0000</p> Signup and view all the answers

    What does the 'I' in the instruction format signify?

    <p>Denotes an immediate value</p> Signup and view all the answers

    Which of the following statements is true regarding the opcode?

    <p>It defines the basic operation to be performed</p> Signup and view all the answers

    What does a two-letter condition like 'EQ' represent in the instruction format?

    <p>A specific comparison outcome</p> Signup and view all the answers

    What would replacing 'ADD' with 'SUB' in 'ADD R3, R2, R1' change?

    <p>The result will be the difference between R2 and R1 instead of their sum</p> Signup and view all the answers

    Study Notes

    Assembling By Hand

    • An assembler translates assembly language into machine code.
    • A disassembler does the opposite, translating machine code into assembly language.
    • When submitting ARMlite code, it is assembled into machine code and stored in memory as binary, hexadecimal, or decimal.
    • Each line of assembly code is translated into machine language.
    • Machine code is the executable form of a computer program and is often represented in files with extensions like .obj or .exe.
    • Assembly language is a symbolic representation of machine code, making it more readable and understandable.

    Language Levels

    • High-level languages are designed to be readable and writable by humans.
    • Assembly language is a lower-level language that is closer to the machine's instruction set.
    • Machine language is the lowest level of programming and is directly understood by the computer's hardware.
    • Compilers translate high-level language programs into assembly or machine code.

    Compiler vs. Assembler

    • Program faults caused by compiler errors are difficult to identify and fix.
    • Compiler developers invest significant effort to ensure the accuracy of their software.
    • Compilers translate high-level languages into assembly or machine code.
    • Assemblers translate assembly language into machine code.
    • Assemblers and disassemblers work with assembly language and machine code, while compilers work with high-level languages. ### Assembling machine code
    • The ARM instruction format is:
      • Opcode{conditions}{flags} Rd, Rn, operand2
    • {cond} is an optional two-letter condition, e.g. EQ
    • {flags} is an optional additional flag, e.g. S
    • Rd is the destination register
    • Rn is the first source register
    • Operand2 is the second register or Rn if there is only one operand
    • Example:
      • MOV R2, R1
      • The condition is always, so Cond is 00
      • I is 0 for immediate, and 1 for register
      • Opcode for MOV is 1101
      • S is 0, as there is no condition code set
      • Rn is 0000, there is no second source register
      • Rd is 0010 (R2)
      • Operand2 is 000000000001 (R1)
      • This translates to: 1110 0001 1010 0000 0010 0000 0000 0001
    • Assembling a more complicated example:
      • ADD R3, R2, R1
      • The condition is always, so Cond is 00
      • I is 1 for register
      • Opcode for ADD is 0100
      • S is 0
      • Rn is 0010 (R2)
      • Rd is 0011 (R3)
      • Operand2 is 000000000001 (R1)
      • This translates to: 1110 0000 1000 0010 0011 0000 0000 0001

    ### Disassembling machine code

    • To disassemble machine code by hand you need to refer to the ARM data sheet
    • Example of disassembling hexadecimal code:
      • 0xE3A02003
      • Cond is 00
      • I is 1
      • Opcode is 1101
      • S is 0
      • Rn is 0000
      • Rd is 0010 (R2)
      • Operand2 is 000000000011 (R3)
      • This translates to: MOV R2, #3
    • Explanation of the example:
      • Condition is Always
      • Opcode is MOV
      • S is 0, so the condition codes are not used
      • Rn is N/A as there is no second register
      • Rd is R2
      • Operand2 is 3
      • Therefore the machine code disassembles to: MOV R2, #3

    Studying That Suits You

    Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

    Quiz Team

    Related Documents

    Assembling and Disassembling PDF

    Description

    Explore the intricacies of assembly language, machine code, and the role of assemblers and disassemblers. This quiz covers the differences between high-level programming languages and their lower-level counterparts. Test your understanding of how code is translated and executed by computers!

    More Like This

    Use Quizgecko on...
    Browser
    Open
    Browser
    Browser