Computer System Organization

Questions and Answers

To move data between peripheral devices and local buffer storage

To synchronize access to the shared memory

One device controller can control multiple devices

To understand the device controller and provide a uniform interface to the operating system Signup and view all the answers

To execute programs in parallel and improve system performance Signup and view all the answers

A common bus Signup and view all the answers

It loads the appropriate registers in the device controller. Signup and view all the answers

It informs the device driver that it has finished its operation. Signup and view all the answers

Via an interrupt. Signup and view all the answers

To provide the necessary speed in handling interrupts. Signup and view all the answers

It is saved and restored after servicing the interrupt. Signup and view all the answers

The interrupted computation resumes. Signup and view all the answers

Study Notes

A modern general-purpose computer system consists of one or more CPUs, device controllers, and a common bus that provides access between components and shared memory.
Each device controller is in charge of a specific type of device (e.g., disk drive, audio device, or graphics display) and can have multiple devices attached.
Device controllers have local buffer storage and special-purpose registers, and are responsible for moving data between peripheral devices and their local buffer storage.

Interrupts alert the CPU to events that require attention, such as completing an I/O operation.
The device controller informs the device driver that it has finished its operation via an interrupt.
The device driver then gives control to other parts of the operating system, possibly returning data or status information.
Interrupts are handled quickly using a table of pointers to interrupt routines, which is stored in low memory.
The interrupt vector is indexed by a unique number to provide the address of the interrupt service routine for the interrupting device.
Operating systems like Windows and UNIX dispatch interrupts in this manner.

The interrupt architecture must save the state information of whatever was interrupted, so that it can restore this information after servicing the interrupt.
If the interrupt routine needs to modify the processor state, it must explicitly save the current state and then restore that state before returning.
After the interrupt is serviced, the saved return address is loaded into the program counter, and the interrupted computation resumes as though the interrupt had not occurred.