# In virtually all systems that include DMA modules, DMA

Question # 00838740 Posted By: wildcraft Updated on: 02/17/2023 01:45 AM Due on: 02/17/2023
Subject Computer Science Tutorials:
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## Assignment Content

Question 1

In virtually all systems that include DMA modules, DMA to main memory is given higher priority than CPU access to main memory. Why?
Question 2

When a device interrupt occurs, how does the processor determine which device issued the interrupt?
Question 3
A system is based on an 8-bit microprocessor and has two I/O devices.

• The I/O con- trollers for this system use separate control and status registers.
• Both devices handle data on a 1-byte-at-a-time basis.
• The first device has two status lines and three control lines.
• The second device has three status lines and four control lines.
• How many 8-bit I/O control module registers do we need for status reading and control of each device?
***Explain your reasoning and show your mathematical calculations on how you derived your answer
• Question 4
A system is based on an 8-bit microprocessor and has two I/O devices.
• The I/O con- trollers for this system use separate control and status registers.
• Both devices handle data on a 1-byte-at-a-time basis.
• The first device has two status lines and three control lines.
• The second device has three status lines and four control lines.
• What is the total number of needed control module registers given that the first device is an output-only device?
***Explain your reasoning and show your mathematical calculations on how you derived your answer
• Question 5
A system is based on an 8-bit microprocessor and has two I/O devices.
• The I/O con- trollers for this system use separate control and status registers.
• Both devices handle data on a 1-byte-at-a-time basis.
• The first device has two status lines and three control lines.
• The second device has three status lines and four control lines.
• How many distinct addresses are needed to control the two devices?

***Explain your reasoning and show your mathematical calculations on how you derived your answer
• Question 6
Consider a microprocessor that has a block I/O transfer instruction such as that found on the Z8000.

• Following its first execution, such an instruction takes five clock cycles to re-execute.
•  However, if we employ a nonblocking I/O instruction, it takes a total of 20 clock cycles for fetching and execution.
• Calculate the increase in speed with the block I/O instruction when transferring blocks of 128 bytes.
**Explain your reasoning and show your mathematical calculations on how you derived your answer

Question 7

• What is the difference between memory-mapped I/O and isolated I/O?

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1. ## Solution: In virtually all systems that include DMA modules, DMA

Tutorial # 00834199 Posted By: wildcraft Posted on: 02/17/2023 01:45 AM
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