I/O Interface MCQ Quiz - Objective Question with Answer for I/O Interface - Download Free PDF

Concept:

Direct memory access (DMA) is a feature of computer systems that allows certain hardware subsystems to access main system memory (random-access memory), independent of the central processing unit (CPU).

Types:

There are three modes of DMA operation:

Burst mode DMA:

• CPU can be put on hold while the DMA transfer occurs and a full block of possibly hundreds or thousands of bytes can be moved
• For the entire duration of the transfer, the CPU stays idle and the DMA controller and the peripheral device gets complete access to the system buses

Transparent mode:

• It takes the most time to transfer a block of data, yet it is also the most efficient mode in terms of overall system performance
• In transparent mode, the DMA controller transfers data only when the CPU is performing operations that do not use the system buses

Cycle stealing mode:

In this only one byte of data transferred in a single request, after one byte of data transfer, the control of the system bus is given back to the CPU transferring one byte of data per request, until the entire block of data has been transferred.

Important Point:

Explanation:

Direct Memory Access (DMA)

Definition: Direct Memory Access (DMA) is a feature of computer systems that allows certain hardware subsystems to access the main system memory (RAM) independently of the central processing unit (CPU). This capability is essential for improving the efficiency and performance of data transfers within the system, particularly for large blocks of data.

Working Principle: In a system with DMA, a DMA controller takes over the responsibility of transferring data between the memory and other hardware components such as disk drives, sound cards, or network cards. The process begins with the CPU setting up the DMA controller with the necessary information, such as the memory addresses, the amount of data to transfer, and the direction of the data flow. Once the setup is complete, the DMA controller handles the data transfer, freeing the CPU to perform other tasks. This transfer occurs directly between the memory and the I/O device, bypassing the CPU, which significantly enhances the system's overall efficiency.

Correct Option Analysis:

The correct option is:

Option 4: Direct Memory Access (DMA)

This option correctly identifies the method that bypasses the CPU for certain types of data transfer operations. In DMA, data is transferred directly between memory and I/O devices without involving the CPU, which significantly enhances data transfer efficiency and system performance.

The correct answer is Option 4.

Key Points

• To understand the correct sequence of a service routine, it is essential to follow the logical order of operations when handling an interrupt:
  • Save contents of processor registers (A): This ensures that the current state of the processor is preserved, so it can be restored later.
  • Check which flag is set (D): Determine which device or event caused the interrupt.
  • Service the device whose flag is set (C): Perform the necessary actions to handle the interrupt.
  • Restore contents of processor registers (E): Restore the processor to its previous state.
  • Turn the interrupt facility on (B): Re-enable interrupts to allow further interrupt handling.

The correct sequence is: A, D, C, E, B.

Additional Information

• This sequence ensures that the system correctly handles the interrupt without losing any critical information or causing inconsistencies.
• Each step is crucial for maintaining the integrity of the processor state and ensuring that the system can continue to operate correctly after the interrupt is serviced.

The correct answer is 11.11 B/sec 

Explanation:

Given:
1. % of time CPU is idle:
   
         \(\frac{y}{x + y} \times 100 = 10\)
   

• y : Memory cycle time ( 40 ms ).
• x : Data transfer time.

2. Solve for x :
   
          \( \frac{40}{40 + x} \times 100 = 10\)
   
   Simplify:
   
           \( \frac{40}{40 + x} = 0.1\)
   
   Multiply both sides by 40 + x :
   
            \(40 = 0.1 (40 + x)\)
   
   Expand:
   
              40 = 4 + 0.1x
   
   Solve for x :
   
              \(36 = 0.1x \implies x = 360 \, \text{ms}.\)
   

Step 2: Calculate Data Transfer Rate

1. In 360 ms, 4 B (bytes) are transferred.
2. Data transferred in 1 ms :
   
                \(\text{Rate per millisecond} = \frac{4}{360} \, \text{B/ms}.\)
   
3. Data transferred in 1 second :
   
                \( \text{Rate per second} = \frac{4}{360} \times 1000 = 11.11 \, \text{B/sec}.\)

Final Answer:
The data transfer rate is: 2) 11.11 B/sec.

The correct answer is 800

Explanation:

To calculate the number of 8-bit characters that can be transmitted per second over a 9600 baud link, we need to consider the total number of bits transmitted per character in asynchronous mode.

Given Data:
1. Baud rate: 9600 bits per second
2. Each character is composed of:

• 1 start bit
• 8 data bits
• 1 parity bit
• 2 stop bits

Thus, the total number of bits transmitted per character is:

         \(\text{Total bits per character} = 1 + 8 + 1 + 2 = 12 \, \text{bits}.\)

Step 1: Calculate the characters per second

• To determine the number of 8-bit characters transmitted per second, divide the baud rate by the total number of bits per character:

                 \(\text{Characters per second} = \frac{\text{Baud rate}}{\text{Total bits per character}} = \frac{9600}{12} = 800.\)

This means the communication link can transmit 800 characters per second in asynchronous mode.

• It is an impact printing technology invented in 1970 by Dr. Andrew Gabor at Diablo Data Systems.
• It uses interchangeable pre-formed type elements, each with typically 96 glyphs, to generate high-quality output comparable to premium typewriters such as the IBM Selectric, but two to three times faster.

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The Correct Answer is BIOS.

Key Points

• The first instructor of the bootstrap loader program of an operating system is stored in BIOS(Basic Input/Output System).
• The bootstrap loader is a programme that resides on the EPROM, ROM or other non-volatile memory of the machine.
• It is executed by the processor automatically when the device is turned on. To continue installing the computer's operating system, the bootstrap loader reads the boot sector of the hard drives.
• The bootstrap loader first conducts the power-on self-test, also referred to as POST, when the machine is switched on or restarted.
• The bootstrap loader loads the operating system for the machine into memory if the POST is successful and no problems are found.
• It is then possible for the machine to access, load, and operate the operating system.
• In computers that have an EFI (Extensible Firmware Interface), the bootstrap loader has been replaced and is now part of the EFI BIOS.

Concept:

A group of wires called bus is used to provide necessary signals for communication between modules. A bus that connects major computer components is called system bus. It connects the CPU, memory and I/O modules. System bus is divided further into three types: data bus, address bus and control bus.

Explanation:

Data bus: These are used to send data to memory and output ports and to receive data from memory and input port. These are bi-directional. The Communication between the components in a microcomputer takes place via the address and data bus.

Address bus: It is unidirectional in nature. Address is send from CPU to memory and I/O port.

Explanation:

Bus: In computer architecture, a bus (related to the Latin “omnibus”, meaning “for all”) is a communication system that transfers data between components inside a computer, or between computers. This expression covers all related hardware components (wire, optical fiber, etc.) and software, including communication protocols.

The types of buses are:

Address Bus:

• It is a unidirectional Bus, which is responsible for only one-way communication.

Data Bus:

• It is a bi-directional bus.
• Data and Instructions pass through this bus to reach the microprocessor.
• This is responsible for the exchange of information between the main memory and microprocessor.

Control Bus:

• The control bus carries control signals partly unidirectional and partly bidirectional
• This tells whether read or write, which operation should be performed that is in which direction the data should flow.

So Utility Bus is not a type of bus used in computer architecture, hence option 4 is the correct answer.

Explanation:

• The interrupt is a signal emitted by hardware or software when a process or an event needs immediate attention.
• It alerts the processor to a high-priority process requiring interruption of the current working process.

Additional InformationSpool

• "Spool" is technically an acronym for simultaneous peripheral operations online. 
• Spooling is a process in which data is temporarily held to be used and executed by a device, program or the system.
• Data is sent to and stored in memory or other volatile storage until the program or computer requests it for execution.

Page File:

A pagefile is a reserved portion of a hard disk and is used as an extension of random access memory (RAM) for data in RAM that is not been used recently.

Stack:

• A stack is a linear data structure.
• The elements in a stack are added and removed only from one end, which is called the TOP.
• Hence, a stack is called a LIFO (Last-In-First-Out) data structure, as the element that was inserted last is the first one to be taken out.
• The push operation is used to insert an element into the stack.
• The pop operation is used to delete the topmost element from a stack.

The correct answer is Uniprocessor.

Key Points

• A computer has only one processor which is known as Uniprocessor.
• A uniprocessor system is defined as a computer system that has a single central processing unit that is used to execute computer tasks.
• As more and more modern software is able to make use of multiprocessing architectures, such as SMP and MPP, the term uniprocessor is therefore used to distinguish the class of computers where all processing tasks share a single CPU. 

Additional Information

• A multiprocessor system consists of more than one processor in a single chip which executes more than one instruction in a single cycle.
• The memory hierarchy of a typical uniprocessor system, including registers, instruction cache, data cache (level 1 cache), level 2 cache, internal memory, and disks. Below each memory level is the range of typical sizes for that memory level.
• Array Processor performs computations on a large array of data.  

The correct answer is option 4.

Key Points An input device converts incoming data and instructions into a pattern of electrical signals in binary code that are comprehensible to a digital computer.

An output device reverses the process, translating the digitized signals into a form intelligible to the user.

An output device is any piece of computer hardware equipment that converts information into a human-readable form. It can be text, graphics, tactile, audio, and video.

Hence the correct answer is Output devices.

• It is an impact printing technology invented in 1970 by Dr. Andrew Gabor at Diablo Data Systems.
• It uses interchangeable pre-formed type elements, each with typically 96 glyphs, to generate high-quality output comparable to premium typewriters such as the IBM Selectric, but two to three times faster.

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The correct answer is option 1.
Concept:-

Block devices are nonvolatile mass storage devices whose information can be accessed in any order. Hard disks, floppy disks, and CD-ROMs are examples of block devices. 

Key Points
Tape Drive:- 

• A tape drive is a data storage device that reads and writes data on a magnetic tape.
• Magnetic tape data storage is typically used for offline, archival data storage.
•  A tape drive provides sequential access storage, unlike a hard disk drive, which provides direct access storage.
• A disk drive can move to any position on the disk in a few milliseconds, but a tape drive must physically wind tape between reels to read any one particular piece of data.

USB port is an I/O device. 

• A USB port is a standard cable connection interface for personal computers and consumer electronics devices.
• USB stands for Universal Serial Bus, an industry standard for short-distance digital data communications.
• USB ports allow USB devices to be connected to each other and transfer digital data over USB cables.

Note:- USB port is not a storage device.
 Additional Information

Character devices:

A character device is one with which the driver communicates by sending and receiving single characters (bytes, octets).

For example:

serial ports, parallel ports, sound cards, etc.

The correct answer is Printer.

Key Points

• Hard copy output devices are devices that provide output on printed paper or other permanent media that is human readable. Examples of devices that produce hard copy are printers, plotters, and microfiche. 
• Hardcopy is a printed copy of information from a computer. Sometimes it refers to as a printout, so it is called hardcopy because it exists as a physical object. Hardcopy is the tangible output that is usually printed. Printers are the most used use to produce a hardcopy output which is printed paper.
• When a document is created on a computer, it is typically saved as a file on the computer's hard drive. This is sometimes referred to as a soft copy.
• While the file can be easily opened and edited on a computer, it can also be easily deleted.
• Therefore, sometimes printing a hard copy is done to create a physical backup of the document.

Important Points

• Output devices:
  • The output device receives information from the computer and provides them to the users. The computer sends information to the output devices in the binary-coded form.
  • The output devices convert them into a form such as printed form or display on a screen, which can be used by the users. The commonly used output devices are the monitor and printer.