8086 Microprocessor and Addressing Modes
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Questions and Answers

What is the purpose of the CMP instruction?

  • To compare two values and set the flags accordingly. (correct)
  • To move data from memory to a register.
  • To add two values together.
  • To perform a subtraction operation and store the result in a register.

    • Which of the following flags is NOT affected by the CMP instruction?

  • Zero Flag (ZF)
  • Carry Flag (CF)
  • Parity Flag (PF) (correct)
  • Sign Flag (SF)

    • What is the value of the Carry Flag (CF) if the CMP instruction compares two values where the first operand is greater than the second operand?

  • undefined
  • 1
  • 0 (correct)
  • -1

    • What is the significance of the Zero Flag (ZF) being set after a CMP instruction?

    <p>The two operands are equal. (D)</p> Signup and view all the answers

    What are the possible values of the Sign Flag (SF) after a CMP instruction?

    <p>0 or 1 (D)</p> Signup and view all the answers

    What is the effect of the SCASB instruction on the flags if the value in AL is less than the value in the memory location pointed to by DI?

    <p>CF = 1, ZF = 0, SF = 1 (A)</p> Signup and view all the answers

    What is the effect of the SCASW instruction on the DI register if the Direction Flag (DF) is 0?

    <p>DI is incremented by 2 (A)</p> Signup and view all the answers

    How does the LODSB instruction work?

    <p>It loads a byte from the memory location pointed to by SI into the accumulator (AL), and then increments SI by 1 (D)</p> Signup and view all the answers

    Which of the following instructions is used to store a string of bytes into memory?

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

    What is the purpose of the STOSB instruction?

    <p>Store a byte from the AL register to a string (D)</p> Signup and view all the answers

    Which of these instructions are used to manipulate strings? (Select all that apply)

    <p>CMPS (A), STOSB (B), LODS (C), MOVS (G)</p> Signup and view all the answers

    What value does the DI register hold after the STOSB instruction executes if the direction flag (DF) is set to 0?

    <p>DI + 1 (D)</p> Signup and view all the answers

    What happens if DF is set to 1 when STOSW is executed?

    <p>DI - 2 (C)</p> Signup and view all the answers

    Which instruction is used to halt the processor after setting an interrupt?

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

    Which instruction is used to call a subroutine?

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

    What signal is used to synchronize an external activity to the processor's internal operation?

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

    Which signal is actively high and causes the processor to immediately terminate its current activity?

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

    What is the purpose of the READY signal?

    <p>To indicate the completion of a data transfer by a slow device or memory. (A)</p> Signup and view all the answers

    What is the role of the 8284A clock generator in the READY signal?

    <p>To synchronize the READY signal before it is sent to the 8086. (C)</p> Signup and view all the answers

    Which signal is triggered during the last clock cycles of each instruction?

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

    Which signal provides the basic timing for processor operation and bus control activity?

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

    What is the significance of the 33% duty cycle in the CLK signal?

    <p>It provides more time for the processor to process instructions. (C)</p> Signup and view all the answers

    What is the size of the 8086's memory address space?

    <p>1 MB (C)</p> Signup and view all the answers

    Which register is used to hold the offset address of the top of the stack memory?

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

    Which of the following is NOT a segment register?

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

    How many bits are in the 8086's instruction pointer (IP)?

    <p>16 (C)</p> Signup and view all the answers

    What is the purpose of the BIU (Bus Interface Unit) in the 8086 architecture?

    <p>To manage memory access (B)</p> Signup and view all the answers

    Which register is used to hold the count value in SHIFT, ROTATE, and LOOP instructions?

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

    How many segment registers are there in the 8086 architecture?

    <p>4 (D)</p> Signup and view all the answers

    Which register is used to hold the index value of the destination operand for string instructions?

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

    What is the size of each segment in the 8086's memory addressing scheme?

    <p>64 KB (C)</p> Signup and view all the answers

    What is the purpose of the Flag register in the 8086?

    <p>To store the status of the CPU after an instruction is executed (C)</p> Signup and view all the answers

    Which generation of Intel processors introduced the HCMOS technology?

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

    What was the primary technology advancement introduced in the Second Generation Intel processors?

    <p>NMOS technology (C)</p> Signup and view all the answers

    What is the maximum physical memory space supported by the Third Generation Intel processors?

    <p>16 MB (B)</p> Signup and view all the answers

    Which of these Intel processors is a 16-bit processor?

    <p>Intel 8086 (A)</p> Signup and view all the answers

    What is the primary benefit of multiplexing signals in the early Intel processors?

    <p>Overcoming pin limitations (C)</p> Signup and view all the answers

    What is the total addressable memory space of the 8086 processor?

    <p>16 MB (D)</p> Signup and view all the answers

    Which of these features was introduced in the Third Generation Intel processors?

    <p>Floating Point Hardware (C)</p> Signup and view all the answers

    What is the primary difference between the Intel 8085 and the Intel 8086 processors?

    <p>The 8085 is an 8-bit processor while the 8086 is a 16-bit processor (D)</p> Signup and view all the answers

    Study Notes

    8086 Microprocessor

    • A 16-bit microprocessor developed by Intel.
    • First released in 1978.
    • Consistently evolved over decades, progressing from 4004 to Pentium 4.
    • Different generations of Intel microprocessors used different technologies, like PMOS, NMOS, HMOS, HCMOS, which affected the processor's features and capabilities (speed, transistors/ density, memory addressing).
    • Feature improvements included faster speed, packing density, more powerful interrupts, and higher memory addressing capability.
    • Package sizes evolved, indicating continuous shrinkage in chip dimensions and increased transistor count.

    Addressing Modes

    • Used in instruction sets to describe the various ways to specify source operand addresses.
    • A program is a set of instructions intended to solve a problem.
    • Instructions are different directions a microprocessor can follow to execute a task.
    • Addressing modes allow the microprocessor to access data from various locations (registers, memory, ports).
    • Different methods for specifying where data comes from are:
      • Register addressing
      • Immediate addressing
      • Direct addressing
      • Register indirect addressing
      • Based addressing
      • Indexed addressing
      • Based indexed addressing
      • String addressing
      • I/O port addressing
      • Relative addressing
      • Implied addressing

    Instruction Set

    • Data transfer instructions (MOV, XCHG, PUSH, POP, IN, OUT) move data between registers, memory, and ports.
    • Arithmetic instructions (ADD, ADC, SUB, SBB, INC, DEC, MUL, DIV, CMP) perform mathematical operations and comparisons.
    • Logical instructions (AND, OR, XOR, TEST, SHR, SHL, RCR, RCL) perform bitwise operations.
    • String manipulation instructions (MOVS, CMPS, SCAS, LODS, STOS) perform operations on strings of data.
    • Processor control instructions (STC, CLC, CMC, STD, CLD, STI, CLI, NOP, HLT, WAIT, ESC, LOCK) control the microprocessor's operation and interact with other systems.
    • Control transfer instructions (CALL, RET, JMP) transfer control flow within a program.
    • Conditional branch instructions provide conditional transfers of control flow.

    Assemble Directives

    • Instructions to the assembler regarding the program being executed.
    • Control the generation of machine codes and the organization of the program.
    • Define program components (segments, procedures, macros).
    • Assign values to variables and allocate memory space.
    • Important assembler directives include DB, DW, SEGMENT, ENDS, ASSUME,ORG, END, PROC, ENDP, and various other directives as needed for particular tasks.

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    8086 Microprocessor PDF

    Description

    Explore the 8086 microprocessor, a 16-bit processor developed by Intel, and its evolution over the decades. This quiz covers the addressing modes used to specify operand addresses in microprocessor instructions. Test your knowledge of how these concepts have advanced and their impact on computing.

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