Homework 4
Elaine Le
Hawaii Pacific University Part A: Textbook p293 Exercises 9.4
Consider the interrupt that occurs at the completion of a disk transfer.
a. Direct memory access (DMA) is an alternative method that avoids the use of the CPU by allowing direct data transfers between memory and I/O devices or peripherals. Once the data is transferred the CPU is notified of the transfer completion and able to resume access of the main memory. It is able to do this with interrupts; are signals that are generated once an action is completed. Normally it suspends the execution of the running program and jumps to a special interrupt service routine. Therefore, at the completion of the disk transfer DMA generates an interrupt signal it is interrupting the CPU and informing it that the operation has been completed and returning the status of the operation. The interrupt signal interrupts the CPU from what it is doing and forces the CPU to take the required action. Then, set up the next request once the disk transfer is completed.
b. …show more content…
Interrupt is used as a completion signal to interrupt the CPU from what is doing and forcing the CPU to take required action and set up the next request. This also better utilization of the CPU as the CPU can also switch to other tasks and the interrupt will notify the CPU about the transfer completion. After servicing the interrupt the CPU goes back to the task and resume from the point where it stop until the next interrupt. Therefore, without interrupts the CPU wouldn’t be notified of the DMA completed actions and data transfers. Interrupt is very important for the proper functioning of DMA.
c. The following are steps that take place after the interrupt
Elaine Le
Hawaii Pacific University Part A: Textbook p293 Exercises 9.4
Consider the interrupt that occurs at the completion of a disk transfer.
a. Direct memory access (DMA) is an alternative method that avoids the use of the CPU by allowing direct data transfers between memory and I/O devices or peripherals. Once the data is transferred the CPU is notified of the transfer completion and able to resume access of the main memory. It is able to do this with interrupts; are signals that are generated once an action is completed. Normally it suspends the execution of the running program and jumps to a special interrupt service routine. Therefore, at the completion of the disk transfer DMA generates an interrupt signal it is interrupting the CPU and informing it that the operation has been completed and returning the status of the operation. The interrupt signal interrupts the CPU from what it is doing and forces the CPU to take the required action. Then, set up the next request once the disk transfer is completed.
b. …show more content…
Interrupt is used as a completion signal to interrupt the CPU from what is doing and forcing the CPU to take required action and set up the next request. This also better utilization of the CPU as the CPU can also switch to other tasks and the interrupt will notify the CPU about the transfer completion. After servicing the interrupt the CPU goes back to the task and resume from the point where it stop until the next interrupt. Therefore, without interrupts the CPU wouldn’t be notified of the DMA completed actions and data transfers. Interrupt is very important for the proper functioning of DMA.
c. The following are steps that take place after the interrupt