Programmable Peripheral Interface 8255 Quiz
91 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 main purpose of the Programmable Peripheral Interface (PPI) 8255?

  • To store data temporarily
  • To control the power supply of the CPU
  • To manage data encryption
  • To interface the CPU with external devices (correct)

    • Which ports are available in the PPI 8255 for input-output operations?

  • PORT D, PORT E, PORT F
  • PORT A, PORT B, PORT C (correct)
  • PORT X, PORT Y, PORT Z
  • PORT 1, PORT 2, PORT 3

    • In which mode does the PPI 8255 operate when the MSB of the control word is set to 0?

  • Input-Output mode
  • Configuration mode
  • Initialization mode
  • BSR mode (correct)

    • What is the function of the control register in the PPI 8255?

    <p>To select different ports and modes</p> Signup and view all the answers

    Which of the following addresses corresponds to PORT B in the PPI 8255?

    <p>81H</p> Signup and view all the answers

    What functionality does Mode 0 in PPI 8255 provide?

    <p>Simple input or output for all ports</p> Signup and view all the answers

    Which component in the PPI 8255 is responsible for chip selection?

    <p>CS'</p> Signup and view all the answers

    In the PPI 8255, what does port C consist of?

    <p>Two 4-bit ports</p> Signup and view all the answers

    What function do the bits of port C serve in the PPI 8255?

    <p>Handshake signals</p> Signup and view all the answers

    Which mode of the PPI 8255 allows only port A to operate while port B can work in either mode 0 or mode 1?

    <p>Mode 2</p> Signup and view all the answers

    Which of the following is a disadvantage of using the PPI 8255?

    <p>Limited memory capacity</p> Signup and view all the answers

    What is the primary role of the interrupt handling capacity in the PPI 8255?

    <p>Synchronizing data transmission</p> Signup and view all the answers

    What needs to be done first to communicate with peripherals using the PPI 8255?

    <p>Determine addresses of port A, B, C, and control register</p> Signup and view all the answers

    What happens when the most significant bit of the control word is set to 0 for the PPI 8255?

    <p>It operates in Bit Set-Reset mode</p> Signup and view all the answers

    How many bits does port C use for handshake signals in Mode 1?

    <p>6 bits</p> Signup and view all the answers

    Which of the following applications is commonly associated with the PPI 8255?

    <p>Generating square waves</p> Signup and view all the answers

    When configured for I/O mode, which ports are available for data transfer in Mode 0?

    <p>All three ports</p> Signup and view all the answers

    How many pins are in the PPI 8255 and how are they generally categorized?

    <p>40 pins; three 8-bit ports</p> Signup and view all the answers

    What is one of the main advantages of the PPI 8255?

    <p>Versatility in operation</p> Signup and view all the answers

    Which mode of PPI 8255 is characterized by no interrupt handling capabilities?

    <p>Mode 0</p> Signup and view all the answers

    What type of tasks can be improved by using a microprocessor with an 8255 PPI?

    <p>System performance during I/O operations</p> Signup and view all the answers

    What are the control registers in the PPI 8255 used for?

    <p>Configuring I/O function for ports</p> Signup and view all the answers

    What is one of the flow control features of the USART?

    <p>Prevents data loss and overloading</p> Signup and view all the answers

    What is a limitation of the 8251 USART?

    <p>Limited maximum data transfer rate of 115.2 kbps</p> Signup and view all the answers

    Which of the following describes the primary purpose of the Intel 8253 and 8254?

    <p>To perform timing and counting functions</p> Signup and view all the answers

    How does the operating frequency of the 8254 compare to the 8253?

    <p>8254 operates up to 10 MHz while 8253 operates up to 2.6 MHz</p> Signup and view all the answers

    Which feature is unique to the 8254 compared to the 8253?

    <p>Read-Back command</p> Signup and view all the answers

    What are the input pins for each counter in the 8253 and 8254?

    <p>Clock and Gate</p> Signup and view all the answers

    Which statement describes the compatibility of the 8253/54 timers?

    <p>Compatible with almost all microprocessors</p> Signup and view all the answers

    Which of the following corresponds to the operation command for reading Counter 1?

    <p>A1=1, A0=0, RD=1, WR=0</p> Signup and view all the answers

    What is a notable disadvantage of using the 8251 USART in a system?

    <p>Limited internal buffer size</p> Signup and view all the answers

    What is the function of the data bus buffer in the 8253/54 architecture?

    <p>It interfaces to the system data bus</p> Signup and view all the answers

    What is the maximum number of interrupt lines that can be achieved by cascading the 8259 chips?

    <p>64 interrupt lines</p> Signup and view all the answers

    Which of the following best describes the main function of the 8251 USART?

    <p>It converts serial data to parallel form and vice versa.</p> Signup and view all the answers

    Which component of the 8259 is responsible for checking and setting the priority of interrupts?

    <p>Priority Resolver</p> Signup and view all the answers

    What function does the Control Logic block serve in the 8259?

    <p>It decides the read and write operations based on pin states.</p> Signup and view all the answers

    What is a disadvantage of the 8255 PPI?

    <p>It offers only three 8-bit ports.</p> Signup and view all the answers

    In which modes can the 8259 be programmed?

    <p>Both edge triggered and level triggered modes</p> Signup and view all the answers

    What is the function of the Data Bus Buffer in the 8251 USART?

    <p>It facilitates communication between 8251 and CPU.</p> Signup and view all the answers

    Which of the following statements about the 8251 USART is true?

    <p>It includes built-in error detection features.</p> Signup and view all the answers

    Which component in the 8251 USART is used to control the data transmission rate?

    <p>Transmit control</p> Signup and view all the answers

    What does the Interrupt Mask Register in the 8259 do?

    <p>It masks individual bits of the interrupt requests.</p> Signup and view all the answers

    What is a key feature of the 8255 PPI technology?

    <p>It is considered older technology being replaced by advanced components.</p> Signup and view all the answers

    What role does the Modem Control play in the 8251 USART?

    <p>It manages the communication over telephone lines.</p> Signup and view all the answers

    What is the primary purpose of the Interrupt Request Register in the 8259?

    <p>To collect all interrupt levels requesting services.</p> Signup and view all the answers

    What are the two control groups in the Programmable Peripheral Interface 8255?

    <p>Control group A and Control group B</p> Signup and view all the answers

    In which mode can port A, B, and C operate if the PPI is set to Mode 0?

    <p>Simple input and output functions</p> Signup and view all the answers

    Which port of the PPI 8255 is divided into two 4-bit ports?

    <p>Port C</p> Signup and view all the answers

    What must be done to select different ports in the PPI 8255 for input-output functions?

    <p>Write a suitable word in the control register</p> Signup and view all the answers

    What is the function of the MSB of the control word in the PPI 8255?

    <p>Determine operating mode</p> Signup and view all the answers

    How is the chip selection signal indicated for the PPI 8255?

    <p>CS'</p> Signup and view all the answers

    What happens when the MSB of the control word for the PPI is set to 1?

    <p>PPI operates in input-output mode</p> Signup and view all the answers

    Which of the following pins is NOT part of the PPI 8255 architecture?

    <p>TXD</p> Signup and view all the answers

    What is the maximum data transfer rate of the 8251 USART?

    <p>115.2 kbps</p> Signup and view all the answers

    Which feature distinguishes the 8254 from the 8253?

    <p>Supports interleaved reads and writes</p> Signup and view all the answers

    What is a disadvantage of the 8251 USART in terms of its buffer?

    <p>Has a limited buffer size</p> Signup and view all the answers

    What function does the Control Word Register serve in the 8253/54 system?

    <p>Specifies the counter configuration and operation</p> Signup and view all the answers

    What technology is used by the 8253?

    <p>N-MOS technology</p> Signup and view all the answers

    Which of the following is NOT a feature of the 8254?

    <p>It provides high-speed DMA capabilities</p> Signup and view all the answers

    Which pin configuration does each counter in the 8253/54 have?

    <p>Two input pins and one output pin</p> Signup and view all the answers

    What aspect of programming the USART can be considered complex?

    <p>Timing and other operational parameters</p> Signup and view all the answers

    Which control input is used for writing to Counter 2 in the 8253/54?

    <p>110</p> Signup and view all the answers

    How many hardware interrupts are available in the 8086 microprocessor without the addition of the 8259?

    <p>5</p> Signup and view all the answers

    What is the function of the Interrupt Request Register in the 8259?

    <p>Stores all interrupt levels requesting service</p> Signup and view all the answers

    What is one of the main advantages of using the 8251 USART?

    <p>Versatility in communication modes</p> Signup and view all the answers

    Which block of the 8259 is responsible for determining the priority of interrupts?

    <p>Priority Resolver</p> Signup and view all the answers

    Which of the following functions does the Transmit Buffer in the 8251 USART perform?

    <p>Transmits parallel data as serial signal</p> Signup and view all the answers

    What happens when both interrupt flags of microprocessors are high in the 8259?

    <p>The output INT pin becomes high</p> Signup and view all the answers

    What role does the Data Bus Buffer serve in the 8259?

    <p>Communicates with the microprocessor</p> Signup and view all the answers

    What is the maximum number of interrupts achievable by cascading multiple 8259 chips?

    <p>64</p> Signup and view all the answers

    Which aspect of the USART helps ensure data accuracy during transmission?

    <p>Parity checking</p> Signup and view all the answers

    What defines the control logic's operation in the 8251 USART?

    <p>Input operation signals</p> Signup and view all the answers

    In which mode can the 8259 be programmed?

    <p>Either edge-triggered or level-triggered mode</p> Signup and view all the answers

    What is a limitation of the 8255 PPI?

    <p>It provides only three 8-bit ports</p> Signup and view all the answers

    Which pin type is commonly associated with modem control in the 8251 USART?

    <p>DSR - Data Set Ready</p> Signup and view all the answers

    What parameter does the 8251 USART control logic NOT use to select the operation to be performed?

    <p>Status register state</p> Signup and view all the answers

    What signal is primarily used for synchronization between the CPU and peripherals in the PPI 8255?

    <p>Handshake signals</p> Signup and view all the answers

    In which mode does the PPI 8255 enable all three ports to function as both inputs and outputs without interrupt handling?

    <p>Mode 0</p> Signup and view all the answers

    What is a defining feature of Mode 2 in the PPI 8255?

    <p>Interrupt handling is enabled for port A.</p> Signup and view all the answers

    Which of the following represents a limitation of the PPI 8255?

    <p>Inability to interface with modern devices</p> Signup and view all the answers

    In BSR mode, what function is enabled within port C?

    <p>Set and reset control</p> Signup and view all the answers

    What characterizes the I/O mode operation of the PPI 8255?

    <p>Enabled interrupt handling capabilities</p> Signup and view all the answers

    What determines the mode of operation for the PPI 8255?

    <p>Control word value's most significant bit</p> Signup and view all the answers

    Which of these applications is NOT commonly associated with the PPI 8255?

    <p>High-speed data logging</p> Signup and view all the answers

    What is one of the main advantages of using the PPI 8255?

    <p>Versatile programming capabilities</p> Signup and view all the answers

    What is a characteristic of the PPI 8255's physical setup?

    <p>It has two 8-bit ports and one control port.</p> Signup and view all the answers

    Which of the following describes a disadvantage of the PPI 8255?

    <p>Limited memory capacity for applications</p> Signup and view all the answers

    How does the PPI 8255 handle interrupts?

    <p>Enabled through specific modes depending on control word</p> Signup and view all the answers

    What is an essential step required to communicate with peripherals via the PPI 8255?

    <p>Implement a control word</p> Signup and view all the answers

    What unique feature does port C provide in bi-directional data bus mode of the PPI 8255?

    <p>6 bits for handshake signals</p> Signup and view all the answers

    Which mode provides no interrupt handling but allows simple input/output functions?

    <p>Mode 0</p> Signup and view all the answers

    Study Notes

    Programmable Interfacing Devices

    • Programmable Peripheral Interface (PPI) 8255:
      • A general-purpose I/O device that connects the CPU to external devices like ADCs, DACs, and keyboards.
      • Contains three 8-bit bidirectional I/O ports: Port A, Port B, and Port C.
      • Each port can be programmed as either input or output.
      • Port C can be further divided into two 4-bit ports: Port C lower and Port C upper.
      • Port C can operate in either Bit Set/Reset (BSR) mode or input/output mode.
      • Port B can operate in mode 0 or mode 1 of the input/output mode.
      • Port A can operate in mode 0, mode 1, or mode 2 of the input/output mode.
      • Features two control groups: Control Group A (Port A and Port C upper) and Control Group B (Port C lower and Port B).
      • Selects ports and modes by writing a control word into the control register.
      • Operates with a +5V regulated power supply.
      • Commonly used for tasks such as traffic light control, generating square waves, and interfacing with DC and stepper motors.

    PPI 8255 Operating Modes

    • Bit Set/Reset (BSR) Mode:
      • Used to set or reset individual bits on Port C.
      • The most significant bit (D7) of the control word is 0.
    • Input/Output Mode:
      • Used to configure ports as input or output.
      • The most significant bit (D7) of the control word is 1.
      • Mode 0: Simple input/output with no interrupt capabilities.
      • Mode 1: Handshake I/O with interrupt capabilities. Either Port A or Port B can be used, and Port C bits act as handshake signals.
      • Mode 2: Bi-directional data bus with interrupt capabilities. Only Port A works bidirectionally, and Port B can be in mode 0 or mode 1. Six bits of Port C are used as handshake signals.

    Programmable Interrupt Controller (PIC) 8259

    • Designed to increase interrupt handling capability.
    • Combines multiple interrupt input sources into a single interrupt output.
    • Provides 8 interrupt lines (IR0 to IR7).
    • Can be programmed in either edge-triggered or level-triggered mode.
    • Allows masking of individual interrupt request register bits.
    • Can be cascaded for up to 64 interrupt lines.
    • Does not require clock cycles.

    Universal Synchronous Asynchronous Receiver Transmitter (USART) 8251

    • Facilitates serial data transmission between the CPU and peripherals.
    • Converts serial data from peripherals to parallel data for the CPU.
    • Converts parallel data from the CPU to serial data for peripherals.
    • Commonly used for communications over serial communication channels, such as RS-232.
    • Key Components:
      • Data bus buffer: Interfaces the internal data bus to the system data bus.
      • Read/Write control logic: Controls the overall working by selecting the operation to be performed based on signals like RD', WR', and CS'.
      • Modem control: Provides connections for modem control signals.
      • Transmit buffer: Converts parallel data to serial data for transmission.
      • Receive buffer: Converts serial data to parallel data for reception.

    Programmable Interval Timer (PIT) 8253/8254

    • A device that generates precise time delays and frequencies.
    • Three independent 16-bit down counters.
    • Input signals: CLOCK and GATE.
    • Output signal: OUT.
    • Operates with frequencies from DC to 10 MHz.
    • Programmable for binary or BCD counting.
    • Counters can be configured to operate in various modes, such as:
      • Mode 0: Interrupt on terminal count (TC).
      • Mode 1: Retriggerable monostable.
      • Mode 2: Rate generator.
      • Mode 3: Square wave generator.
      • Mode 4: Software triggered strobe.
      • Mode 5: Hardware triggered strobe.
    • 8254 features advanced features compared to 8253:
      • Higher maximum operating frequency (10 MHz vs. 2.6 MHz).
      • READ BACK command, allowing users to check the counter's count value, programmed mode, current mode, and status.
      • Interleaving of reads and writes for the same counter.

    Comparison of 8253 and 8254

    • 8253:
      • Operating frequency: 0 - 2.6 MHz
      • Technology: N-MOS
      • READ BACK command: Not available
      • Interleaved reads and writes of the same counter: Not allowed
    • 8254:
      • Operating frequency: 0 - 10 MHz
      • Technology: H-MOS
      • READ BACK command: Available
      • Interleaved reads and writes of the same counter: Allowed

    Programmable Interfacing Devices

    • Programmable Interfacing Devices are used to interface the CPU with external devices like ADC, DAC, keyboard etc.

    Programmable Peripheral Interface 8255

    • The 8255 is a general-purpose programmable I/O device.
    • It has three 8-bit bi-directional I/O ports: Port A, Port B, and Port C.
    • Port C can also work in Bit Set/Reset (BSR) mode.
    • The 8255 is a versatile component due to its multiple operating modes.
    • The 8255 is relatively easy to program and widely compatible.
    • The 8255 is an affordable and low-cost option.

    8255 Operating Modes

    • The 8255 operates in two modes:
      • Bit Set/Reset (BSR) Mode: Used to set or reset individual bits of Port C.
      • Input/Output (I/O) Mode: Further divided into three modes:
        • Mode 0: All ports can work as simple input or output ports.
        • Mode 1: Handshake or strobed I/O mode, either Port A or Port B can work as input/output ports (with Port C for handshaking). Supports interrupt handling.
        • Mode 2: Bi-directional data bus mode, only Port A is used for data transfer, Port B can work in Mode 0 or Mode 1, and 6 bits of Port C are used for handshaking. Supports interrupt handling.

    8255 Advantages & Disadvantages

    • Advantages:
      • Versatility: Multiple operating modes.
      • Ease of use: Simple programming.
      • Compatibility: Widely used.
      • Low cost.
    • Disadvantages:
      • Limited functionality: Compared to newer devices.
      • Limited ports: Only 3 8-bit ports.
      • Limited resolution: 8-bit resolution per port.
      • Obsolete technology.

    8255 Programming & Interfacing

    • The 8255 requires three steps for communication with peripherals:
      • Determine addresses of Port A, B, C, and Control register.
      • Write a control word to the control register.
      • Write I/O instructions to communicate with peripherals through ports A, B, C.
    • Common applications of 8255:
      • Traffic light control.
      • Square wave generation.
      • Interface DC motors and stepper motors.

    Programmable Interrupt Controller PIC (8259)

    • The 8259 is a programmable interrupt controller chip.
    • It increases the interrupt handling capability of the microprocessor (8085/8086).
    • It combines multiple interrupt input sources into a single interrupt output.
    • It provides 8 interrupt lines (IR0 to IR7).
    • The 8259 can be programmed for edge or level-triggered interrupt mode.
    • Individual interrupts can be masked.
    • Multiple 8259 chips can be cascaded for up to 64 interrupt lines.

    8259 Architecture

    • Data Bus Buffer: Communicates between 8259 and microprocessor.
    • Read/Write Control Logic: Enables data flow based on RD/WR signals.
    • Control Logic: Controls the functionality of the 8259.
    • Interrupt Request Register (IRR): Stores pending interrupt requests.
    • Interrupt Service Register (ISR): Stores the currently being serviced interrupt.
    • Interrupt Mask Register: Stores masked interrupts.
    • Priority Resolver: Determines the priority of interrupts.
    • Cascade Buffer: Used for cascading multiple 8259 chips.

    Universal Synchronous Asynchronous Receiver Transmitter USART (8251)

    • The 8251 is a universal synchronous asynchronous receiver transmitter.
    • It converts serial data to parallel data and vice-versa.
    • It acts as an intermediary between the CPU and peripheral devices.

    8251 Architecture

    • Data Bus Buffer: Handles data transfer between the 8251 and the system data bus.
    • Read/Write Control Logic: Controls the operation of the 8251.
    • Modem Control: Handles communication over telephone lines or cable wires.
    • Transmit Buffer: Converts parallel data to serial data for transmission.
    • Transmit Control: Controls the data transmission process.
    • Receive Buffer: Stores received data in serial format.
    • Receive Control: Controls the data reception process.

    8251 Advantages & Disadvantages

    • Advantages:
      • Versatility: Can be used for synchronous and asynchronous communication.
      • Error detection: Parity checking for data accuracy.
      • Flow control: Regulates data transmission and reception.
      • Compatibility: Widely compatible with various microprocessors.
      • Ease of use: Simple interface pins and registers.
    • Disadvantages:
      • Limited speed: Low maximum data transfer rate.
      • Limited buffer size: May lead to data loss if not read promptly.
      • Complex programming: Careful timing and parameter handling.
      • Cost: Adds cost to the system.
      • Limited functionality: Lacks advanced features like DMA.

    Programmable Interval Timer PIT (8253/8254)

    • The 8253/8254 are programmable interval timers.
    • They perform timing and counting functions using three 16-bit counters.
    • Each counter has a clock input, gate input, and output.
    • They can be programmed for binary or BCD counting.

    8253 vs 8254

    • The 8254 has a higher operating frequency (up to 10 MHz), while the 8253 has a frequency of 0-2.6 MHz.
    • The 8254 uses H-MOS technology, while the 8253 uses N-MOS technology.
    • The 8254 has a Read-Back command that allows users to check the count value, program mode, and status.

    8253/8254 Architecture

    • Three independent 16-bit counters: For timing and counting functions.
    • Data Bus Buffer: Interface between the 8253/8254 and the system data bus.
    • Read/Write Control Logic: Controls access to counters and the control word register based on RD, WR, CS, A0, A1 signals.
    • Control Word Register: Programs the counters' mode, read/write operations, and selection.

    8253/8254 Pin Description

    • CLOCK: Clock input for the counter.
    • GATE: Enables or disables the counter.
    • OUT: Output of the counter.
    • RD: Read input for the 8253/8254.
    • WR: Write input for the 8253/8254.
    • CS: Chip select input for the 8253/8254.
    • A0 & A1: Address lines for selecting the counter or the control word register.

    8253/8254 Control Word Register

    • The control word register in the 8253/8254 is accessed by sending a special command to the chip.
    • The control word specifies the counter mode, read/write operation, and whether the counter is to be read or written to.

    Studying That Suits You

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

    Quiz Team

    Description

    Test your knowledge on the Programmable Peripheral Interface (PPI) 8255. This quiz covers key features, operational modes, and application areas of this versatile I/O device used in interfacing with CPUs and peripherals. Assess your understanding of the ports, modes, control groups, and their functionalities.

    More Like This

    Use Quizgecko on...
    Browser
    Open
    Browser
    Browser