Computer I/O Devices and Modules

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Questions and Answers

What does the D0 bit signify in the Intel 8237A Registers?

Memory-to-memory E/D (correct)

Fixed/Rotating priority

Channel 0 address hold E/D

Normal/Compressed timing

Which channel's mask bit is controlled by the D1 bit?

Channel 0

Channel 2

Channel 1 (correct)

Channel 3

What does the D6 bit indicate regarding the Channel 0 request?

Request active high/low (correct)

Demand mode

Priority type

Enable/disable feature

Which mode is determined by the D7 bit for Channel 0?

Demand/single mode Signup and view all the answers

What does the D4 bit in the Intel 8237A Registers determine?

Fixed/Rotating priority Signup and view all the answers

How many logical partitions can be created per system in the IBM z13 architecture?

85 Signup and view all the answers

What is the maximum number of channels that can be supported per subchannel set in the IBM z13?

64k Signup and view all the answers

Which of the following best describes the structure of the I/O system in IBM z13?

It features multiple types of I/O such as programmed, interrupt-driven, and direct memory access. Signup and view all the answers

How many subchannel sets are available per channel subsystem in the IBM z13 architecture?

4 Signup and view all the answers

What is the role of I/O channels in the IBM z13 system structure?

To facilitate communication between external devices and processors. Signup and view all the answers

What is the primary purpose of an I/O module?

To exchange control, status, and data with external devices Signup and view all the answers

Which category does a video display terminal (VDT) belong to?

Human readable Signup and view all the answers

What type of external device is suitable for communicating with remote devices?

Communication Signup and view all the answers

Which of the following is NOT a characteristic of machine readable devices?

Used primarily for human interaction Signup and view all the answers

Which of these is an example of a peripheral device?

Magnetic disk Signup and view all the answers

What type of devices are designed for communicating with computer users?

Human readable devices Signup and view all the answers

How do external devices connect to a computer?

Through an I/O module Signup and view all the answers

Which of these is an example of a human readable device?

Printers Signup and view all the answers

What is the main advantage of interrupt-driven I/O over programmed I/O?

It frees the processor to perform other tasks while waiting for I/O operations to complete. Signup and view all the answers

How does the I/O module communicate with the processor when it is ready for data exchange?

By issuing an interrupt to the processor. Signup and view all the answers

What challenge arises when multiple I/O modules use interrupts?

Identifying which I/O device issued the interrupt to the processor. Signup and view all the answers

What happens after the processor acknowledges an interrupt from the I/O module?

The processor performs the specified data transfer and then resumes its previous task. Signup and view all the answers

Which of the following is NOT a design issue in implementing interrupt-driven I/O?

Identifying which processor controls each I/O device. Signup and view all the answers

What is the basic unit of exchange between the user and the computer?

Character Signup and view all the answers

How many different characters can be represented by the 7-bit binary code?

128 Signup and view all the answers

Which of the following is an example of a control character?

Carriage return Signup and view all the answers

What happens when a user presses a key on the keyboard?

An electronic signal is generated. Signup and view all the answers

What does the I/O module do with the IRA code characters on output?

Transmits codes to external devices. Signup and view all the answers

What type of characters can be printed on paper or displayed on a screen?

Printable characters Signup and view all the answers

What role does the transducer in the keyboard play?

It interprets the IRA code and sends signals. Signup and view all the answers

What types of input does the keyboard primarily provide?

Textual and commands Signup and view all the answers

What is the maximum data rate that current Ethernet systems support?

100 Gbps Signup and view all the answers

What fundamental structure has Ethernet evolved from?

Bus-based system Signup and view all the answers

What is the maximum data rate of the current version of Wi-Fi, 802.11ac?

3.2 Gbps Signup and view all the answers

In an Ethernet network, what device is central to connecting all devices?

Central switch Signup and view all the answers

What type of devices does Wi-Fi technology commonly connect?

Computers, tablets, smartphones, and IoT devices Signup and view all the answers

What has contributed to the increase in the standards for Wi-Fi technology?

Improvements in antenna and transmission techniques Signup and view all the answers

Why has Wi-Fi become essential in enterprises?

It enhances worker productivity and network effectiveness Signup and view all the answers

What feature of public hotspots has changed significantly in recent years?

They provide free internet access in most public places Signup and view all the answers

Study Notes

Input/Output Organization

Input/output (I/O) devices provide a way to exchange data between the computer and its external environment.
They are attached to the computer via an I/O module.
There are three categories of external devices: human-readable, machine-readable, and communication devices.
Human-readable devices allow communication with the computer user (e.g., video display terminals, printers).
Machine-readable devices facilitate communication with equipment like magnetic disks, sensors, and actuators.
Communication devices enable communication with remote devices, machines, or other computers.
Each external device has a unique identifier (address).

I/O Modules

An I/O module manages the exchange of data between the external devices and the computer's main memory.
The module plays a crucial role in coordinating the flow of data between internal resources and external devices.
I/O modules handle processor communication.
They decode commands, report data/status, recognize addresses, and communicate with devices.
I/O modules also handle data buffering to balance device speeds with memory speeds and detect transmission errors.

I/O Commands

Control: Activates the device to perform a specific function.
Test: Checks status conditions of the device and its peripherals.
Read: Acquires data from the device and stores it in an internal buffer.
Write: Sends data from a buffer to the device.

I/O Techniques

Programmed I/O: The processor directly controls the I/O operation. The processor is responsible for waiting for the device to complete the process, which can waste processor time if the I/O operation is slower than the processor.
Interrupt-driven I/O: The processor issues a command and continues executing other instructions. The I/O module interrupts the processor when the operation is complete. This reduces wasted processor time.
Direct Memory Access (DMA): The I/O module directly transfers data between memory and the device without processor involvement. This is efficient for large data transfers.

I/O Mapping

Memory-mapped I/O: Devices and memory share the same address space. I/O instructions look like memory read/write operations; many memory commands are applicable.
Isolated I/O: Separate address spaces are used for memory and I/O devices. Special I/O instructions are used for I/O operations; these use separate addresses dedicated to I/O.

Interrupt Processing

Hardware components may interrupt the CPU, indicating that they require service.
The CPU saves its current state, executes the required service routine, and then restores its previous state.
Multi-interrupt lines may need a mechanism to determine which device triggered the interrupt. Strategies include software polling, daisy chaining (hardware polling), vectored, and bus arbitration.

DMA

Direct Memory Access (DMA) enables I/O modules to transfer data directly to/from memory without processor involvement, improving I/O speed for big data transfers.
Different DMA configurations exist, with varying levels of integration of the DMA controller into the system bus architecture.

Modern I/O Interfaces

Various standards (e.g., USB, FireWire, SCSI, PCI Express, Ethernet, Wi-Fi) are used for transferring data between computers and peripherals.
Each standard offers different characteristics such as speed, power usage, and connectivity.

Direct Cache Access (DCA) strategies seek improvements in data transfer rates for high-speed networks, such as network I/O.
Existing methods(DMA) might have lower efficiency in supporting the increased demand for high-speed data transfers.
DCA is often used with multiple levels of caches in modern CPUs.

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Description

This quiz covers the fundamental concepts of Input/Output (I/O) devices and modules in computer architecture. Explore the different categories of external devices such as human-readable, machine-readable, and communication devices, along with the role of I/O modules in data exchange. Test your knowledge on how these components interact within a computer system.