quiz

Direct Memory Access (DMA)

Direct Memory Access (DMA) in Computer Systems

1. What is the main purpose of Direct Memory Access (DMA) in computer systems?

  • A) Increasing the speed of the CPU
  • B) Allowing peripheral devices to directly access system memory without CPU intervention
  • C) Managing memory allocation for running programs
  • D) Enhancing the graphical performance of the computer
B) Allowing peripheral devices to directly access system memory without CPU intervention Explanation

2. In Burst Transfer mode, when does the DMA controller release control of the bus?

  • A) After each byte of data is transferred
  • B) After a fixed number of cycles
  • C) After the entire block of data is transferred
  • D) Immediately after gaining control of the bus
C) After the entire block of data is transferred Explanation

3. Which of the following components is essential for DMA to function?

  • A)  CPU
  • B)  DMA Controller 
  • C) GPU
  • D) Cache Controller
B) DMA Controller  Explanation

4. Which of the following is an example of a DMA controller?

  • A) Intel 8259
  • B) Intel 8086
  • C) Intel 8237
  • D)  Intel 8251
C) Intel 8237 Explanation

5. Which of the following registers is NOT typically found in a DMA controller?

  • A) Memory address register
  • B) Byte count register
  • C) Control Register
  • D)  Instruction register
D) Instruction register Explanation

6. What does the term “bus mastering” refer to in the context of DMA?

  • A) The ability of the CPU to control all bus operations
  • B) The DMA controller's capacity to manage memory addresses
  • C) The ability of peripherals to control the system bus and access memory directly
  • D) The synchronization of data transfer rates between the CPU and memory
C) The ability of peripherals to control the system bus and access memory directly Explanation

7. In which mode does the DMA controller transfer data only when the CPU is not using the system buses?

  • A) Transparent Mode
  • B) Cycle Stealing Mode
  • C) Burst Mode
  • D) Polling Mode
A) Transparent Mode Explanation

8. What problem can occur if a device writes to memory using DMA and the CPU reads from the cache?

  • A) Data redundancy
  • B) Cache coherency problem
  • C) Increased latency
  • D) Data compression
B) Cache coherency problem Explanation

9. Which memory type is typically involved in DMA transfers?

  • A) Cache memory
  • B) Read-Only Memory (ROM)
  • C) Main memory (RAM)
  • D) Virtual memory
C) Main memory (RAM) Explanation

10. What signal does the DMA controller use to request access to the system bus?

  • A) Bus Acknowledge
  • B) Bus Release
  • C) Memory Access
  • D) Bus Request
D) Bus Request Explanation

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