CS214P Assembly Language Quiz on Memory Addressing
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Questions and Answers

What happens to the stack pointer (SP) after a PUSH operation?

  • It is decremented by 2. (correct)
  • It remains unchanged.
  • It is set to zero.
  • It is incremented by 2.

What is restored when executing a POP operation?

  • The program counter (PC).
  • The stack pointer (SP) only.
  • The contents of memory.
  • The contents of the top of the stack. (correct)

What happens to the values in AX and BX after executing two consecutive PUSH AX operations?

  • Both values are stored in the stack. (correct)
  • The last pushed value replaces the first.
  • Only the first value is stored in the stack.
  • Both values are lost.

What does SP=0 typically indicate during program execution?

<p>The stack is at its base. (C)</p> Signup and view all the answers

What are the primary stages of instruction execution in a processor?

<p>Fetch, decode, execute. (C)</p> Signup and view all the answers

After executing a POP operation, what happens to the stack pointer (SP)?

<p>It is incremented by 2. (B)</p> Signup and view all the answers

What do operands in an instruction refer to?

<p>Data references needed by the instruction. (B)</p> Signup and view all the answers

How does the assembler translate a program written in symbolic code?

<p>Into machine code as a .COM or .EXE program. (C)</p> Signup and view all the answers

What is the initial value of the Instruction Pointer (IP) after loading the program?

<p>0000 (A)</p> Signup and view all the answers

How does the processor calculate the address of the next instruction to be executed after 'mov AL'?

<p>It adds 2 to the current IP. (B)</p> Signup and view all the answers

What is the new address of the Data Segment (DS) after initialization?

<p>05D1 (B)</p> Signup and view all the answers

What type of operands can an instruction have?

<p>Zero to three operands (C)</p> Signup and view all the answers

If the current instruction 'mov AL, 4A' is executed, what is the next instruction address?

<p>05D28 (A)</p> Signup and view all the answers

After executing 'mov CX, BX', which type of operand is BX classified as?

<p>Register Operand (B)</p> Signup and view all the answers

What is the offset when the instruction addresses data at location 05D26?

<p>0016H (B)</p> Signup and view all the answers

What happens to the IP register after an instruction that is 2 bytes long is executed?

<p>It increments by 2. (D)</p> Signup and view all the answers

What is an absolute address?

<p>A 20-bit value that directly references a specific location in memory (D)</p> Signup and view all the answers

How is a segment: offset address structured?

<p>It combines a segment starting address with an offset value. (C)</p> Signup and view all the answers

What does a segment start address refer to?

<p>The first address in a memory segment (C)</p> Signup and view all the answers

What does the segment register NOT need to store?

<p>The zero digit of the segment address (D)</p> Signup and view all the answers

How is the segment beginning defined?

<p>It always starts on a paragraph boundary. (B)</p> Signup and view all the answers

What does the address 04F03 represent in the context of segment addressing?

<p>An offset value relative to the segment start address (D)</p> Signup and view all the answers

In the context of segments, what is the function of a stack segment?

<p>To manage variable storage dynamically (C)</p> Signup and view all the answers

What value is typically indicated by the rightmost hex digit being zero in a segment?

<p>Denotes a valid segment start address (D)</p> Signup and view all the answers

What is the actual memory address calculated from DS= 038E(0)H and offset = 0032H?

<p>038E32H (C)</p> Signup and view all the answers

Which register holds the offset address of the next instruction to execute?

<p>IP (D)</p> Signup and view all the answers

Which registers are classified as general-purpose registers?

<p>AX, BX, CX, DX (B)</p> Signup and view all the answers

What does the value in the flag register represent?

<p>The status of arithmetic and control conditions (C)</p> Signup and view all the answers

If the flag register has a value of 0F19H, which status is indicated by the ZF bit?

<p>Zero result from the last operation (C)</p> Signup and view all the answers

Which of the following describes the segment register CS?

<p>Points to the code segment for executing instructions (B)</p> Signup and view all the answers

What is the function of the instruction represented by the general-purpose register expressed as 'MOV [BX], AX'?

<p>To store the value of AX into the memory address pointed to by BX (A)</p> Signup and view all the answers

Which option provides a valid segment: offset pair for the actual address 28F30H?

<p>CS:28F00H (C)</p> Signup and view all the answers

What is the initial state of the processor during the BIOS boot process?

<p>Reset state (A)</p> Signup and view all the answers

What is the entry point address for BIOS in ROM?

<p>FFFF0H (B)</p> Signup and view all the answers

What does the BIOS perform as part of its initialization process?

<p>Clear memory locations to zero (C)</p> Signup and view all the answers

What is the role of the boot strap loader in the BIOS process?

<p>Load system files from disk into memory (B)</p> Signup and view all the answers

Which of the following components is checked by the BIOS during the boot process?

<p>Input/output ports (A)</p> Signup and view all the answers

What does the Interrupt Vector Table provide during the BIOS boot process?

<p>Hardware addresses (D)</p> Signup and view all the answers

What is cleared as a part of the BIOS boot process?

<p>Memory locations (A)</p> Signup and view all the answers

What action does BIOS take first after power is turned on?

<p>Clear memory locations (D)</p> Signup and view all the answers

What does the BIOS use to begin the boot process?

<p>Interrupt Vector Table (C)</p> Signup and view all the answers

What is a key difference between .COM and .EXE files?

<p>.EXE files have separate segments for code, data, and stack. (B)</p> Signup and view all the answers

What is stored at SS:SP in the stack during program execution?

<p>Return address of the previous operation (B)</p> Signup and view all the answers

Which part of memory does the BIOS data area begin at?

<p>Location 40 (C)</p> Signup and view all the answers

What is the purpose of the Stack Frame in a program?

<p>To maintain the execution state of the program (A)</p> Signup and view all the answers

What action does the BIOS take when it checks the disk for system files?

<p>Transfers control to the boot strap loader (A)</p> Signup and view all the answers

What does a PUSH operation do in a stack?

<p>Stores a value at the highest memory location (A)</p> Signup and view all the answers

Which component transfers control to a program for execution starting at offset 0?

<p>Program loader (C)</p> Signup and view all the answers

Flashcards

PUSH AX

Pushes the contents of the AX register onto the stack, decreasing the stack pointer (SP).

Stack Pointer (SP)

A register that holds the memory address of the top of the stack.

PUSH BX

Pushes the contents of the BX register onto the stack, decreasing the stack pointer (SP).

POP BX

Pops (removes) the top data from the stack and stores it in the BX register, increasing the SP.

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POP AX

Pops (removes) the top data from the stack and stores it in the AX register, increasing the SP.

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Stack

Special area in memory for storing data (data structure)

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Execution sequence

Fetch, decode, and execute are the basic steps for processing an instruction

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Fetch-Decode-Execute Cycle

The process a computer follows to execute an instruction. It fetches the instruction from memory, decodes it, and then executes it.

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Instruction Size (Bytes)

The number of bytes needed to represent an instruction in memory.

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Program Counter (PC)

A register that holds the memory address of the next instruction to be executed.

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Memory Address

A unique identifier that specifies a location in computer memory.

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Instruction Operand

The data or memory location that an instruction uses or modifies.

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Data Segment (DS)

A segment in memory that stores data used by a program.

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Code Segment (CS)

A segment in memory containing the program's instructions.

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Instruction Addressing Modes

Different ways of specifying operands (data locations) within instructions.

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MOV AL, [Memory_address]

The instruction copies a value from the memory specified by the address to the AL register.

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Stack

A last-in, first-out (LIFO) area in memory used to store temporary information.

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Absolute Address

A 20-bit value that directly points to a specific memory location.

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Segment:Offset Address

A method of addressing memory that combines the starting address of a segment with an offset value.

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Segment

A block of memory, with the starting address aligned to a paragraph boundary (divisible by 16).

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Paragraph Boundary

An address divisible by 16 (hexadecimal 10).

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Segment Register

Registers that hold the starting address of a segment (e.g. CS, DS, SS).

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Offset

A value used in conjunction with a segment to calculate the precise location within that segment.

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Memory (Addressing)

Organizing and accessing instructions and data in memory.

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Code Segment

Part of memory that stores program instructions.

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Data Segment

Part of memory that stores program data.

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Stack Segment

Part of memory that stores data in a last-in, first-out fashion.

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Segment Register

A 16-bit register that holds the starting address of a segment in memory.

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Offset

A 16-bit value that specifies the distance from the starting address of a segment to a specific location within that segment.

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Memory address (actual)

Calculated by combining the segment address with the offset to locate a specific byte in memory.

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CS:IP

Used by the processor to locate the next instruction to execute: CS is code segment register, IP is instruction pointer.

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SS:SP

Specifies a memory address for data on the stack. SS is stack segment register, SP is stack pointer.

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General Purpose Registers

Registers (AX, BX, CX, DX) used for various arithmetic and data manipulation operations.

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Flag Register

A 16-bit register that holds status flags indicating conditions of an arithmetic result or other operations.

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Segment:Offset Scheme

A method of addressing memory by combining a segment register with an offset which provides a way to address each byte within memory.

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Instruction Pointer (IP)

A 16-bit register that holds the offset of the next instruction to be executed in a segment of memory.

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Stack Pointer (SP)

A 16-bit register that points to the top of the stack.

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BIOS Boot Process

The initial sequence of events when a computer starts up, involving the BIOS (Basic Input/Output System) checking hardware and loading the operating system.

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BIOS Boot Process

The initial sequence of operations performed by the BIOS (Basic Input/Output System) when a computer is turned on.

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Interrupt Vector Table (IVT)

A table in memory (at specific location) containing addresses (segment and offset) to handle various interrupts.

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Processor Reset State

The default state of the CPU (Central Processing Unit) when power is first applied.

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FFFF0H

The memory address where the first instruction of a BIOS boot routine is located.

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BIOS Data Area

A region in memory holding the status of connected hardware devices.

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Bootstrap Loader

A program that loads the operating system from storage into memory.

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Interrupt Vector Table

A table that maps specific interrupts to corresponding interrupt handlers. Provides a jump point to specific routines in BIOS.

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.COM file

Executable program format using a single segment for code, data, and stack.

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BIOS data area

Memory area where useful data for BIOS routines are stored.

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Boot Strap Loader

A program that loads system files from a storage device into memory.

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.EXE file

Executable program format with separate segments for code, data, and stack.

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Program Segment Prefix (PSP)

A 256-byte area holding program state information (like command-line arguments).

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System Files

Essential files needed for the operating environment to run.

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Stack

A memory area for temporary storage during program execution, especially for function calls and subroutines.

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Memory Management

The process of allocating and managing computer memory.

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Input/Output Management

The process of managing input (taking data from an external device) and output to an external device.

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Stack Frame

A part of the stack reserved for a specific subroutine's state.

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File Management

Method of controlling computer files.

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PUSH operation

Stores data on top of the stack, adjusting the stack pointer.

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POP operation

Retrieves data from the top of the stack, adjusting the stack pointer.

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Program Loading

The process of loading a program into memory.

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Interrupt Handling

The process of managing interrupts from hardware (keyboard or mouse), and responding to hardware interrupts appropriately.

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Study Notes

Course Information

  • Course Title: Assembly Language
  • Course Code: CS214P
  • Grade Level: Third Year Computer Science
  • Institution: Mansoura University, Faculty of Computers and Information, Department of Computer Science
  • Semester: First Semester 2020-2021
  • Instructor: Sara El-Metwally, Ph.D.

Addressing Data in Memory

  • Absolute Address: A 20-bit value directly referencing a specific memory location.
  • Segment: Offset Address: Combines the starting address of a segment with an offset value.

Example of Addressing in Memory

  • Memory (Stack): Illustrates how absolute addresses and segment-offset addresses are used to locate memory locations. Shows example locations like (04A27, 04A26).

Segments and Addressing

  • Program: Shows how code, data, and subroutines are organized. Code, data, and stack segments are directly related to organization.
  • Stack: Is a memory region for managing subroutines and data within programs. Shows example stack addresses and offsets.
  • Segment Registers with relation to memory map: Explains the code segments, data segments, and stack segment with the addresses. Introduces CS, DS, and SS registers.

Registers

  • Segment Registers: Control access to different memory segments (CS, DS, SS, ES). CS, DS, SS, ES are segment registers.
  • Pointer Registers: Provide addresses for instructions (IP) and stack (SP, BP). IP, SP, BP are pointers.
  • General Purpose Registers: Used for calculations (AX, BX, CX, DX). AX, BX, CX, DX are used for calculations.
  • Index Registers: Support string and array operations (SI, DI) and SI and DI are index registers.
  • Flag Register: Reflects the current status of the processor. (OF, DF, IF, TF, SF, ZF, AF, PF, CF)

Instruction Execution and Addressing

  • Instruction Format: Each instruction comprises an operation and operands.
    • Opcodes: specifying the operations.
    • Operands: specifying data.
  • Execution Steps: Instruction execution involves fetching, decoding, and executing the instructions.

Memory Organization in .EXE/ .COM programs

  • .COM files: Consists of a single segment containing code, data, and stack
  • .EXE files: Separate segments for code, data, and stack

Program Loader

  • Role: Loads .EXE programs into memory.
  • Operation: Loads program code, data, and stack into memory based on addresses. This includes getting command-line arguments and setting up memory segments.

BIOS Boot Process

  • Initial Processor State: The processor is set to a reset state. Memory locations are cleared to zero, and a parity check is done.
  • BIOS Initialization: The BIOS loads. The BIOS then checks the disk for operating system files and accesses the boot strap loader.
  • Interrupt Vector Table: Contains the addresses of interrupt service routines.

I/O Interface

  • Hierarchy: Describes how user programs, operating system, BIOS, and hardware interact for input/output tasks.

The Stack

  • Purpose: Used to store temporary data, return addresses, and context when subroutines are called
  • Operation: Data is stored at higher stack address and stores sequentially downward in the stack.
  • Frame: Section of stack reserved for specific routine.
  • PUSH and POP Instructions: Used to store and retrieve data from the stack. PUSH instructions decrement SP by 2 to store the contents of the register in the stack, POP increments SP by 2 to retrieve the contents in the stack based on the location stored in SP.

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Mansoura University Assembly Language Lecture Notes (2020-2021) PDF

Description

Test your understanding of memory addressing in Assembly Language, specifically focusing on absolute and segment-offset addressing. This quiz covers how different memory locations are referenced and organized within programs, including the stack and segments. Prepare to apply your knowledge about memory management concepts learned in the course.

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