CPU Interrupts vs. Exceptions

What is the primary difference in the source of external interrupts and internal exceptions?

External interrupts originate from outside the CPU, while internal exceptions originate from within the CPU during instruction execution.

How does the relationship between an internal exception and the current instruction differ from that of an external interrupt?

Internal exceptions are synchronous, meaning they are directly caused by the current instruction. External interrupts are asynchronous and unrelated to the current instruction.

When are external interrupts typically detected by the CPU?

External interrupts are typically detected after a single instruction has completed execution.

When are internal exceptions typically detected by the CPU?

Internal exceptions are typically detected during the execution of an instruction.

External interrupts originate from {{c1::CPU external}} sources, whereas internal exceptions originate from {{c2::CPU internal}} sources.

An internal exception is {{c1::synchronous}} with the instruction that caused it, while an external interrupt is {{c2::asynchronous}}.

External interrupts are detected {{c1::after a single instruction execution is completed}}, while internal exceptions are detected {{c2::during instruction execution}}.

List two typical sources of external interrupts.

Typical sources include the system clock and I/O devices.

List two typical sources of internal exceptions.

Typical sources include illegal operations, address out-of-bounds errors, page faults, and system calls.

Which of the following best describes the timing of an external interrupt?

1. 1. Synchronous with the instruction that caused it
2. 2. Detected during the execution of an instruction
3. 3. Asynchronous and unrelated to the current instruction
4. 4. Only occurs when the CPU is idle

Which of the following best describes the timing of an external interrupt?

1. Synchronous with the instruction that caused it
2. Detected during the execution of an instruction
3. ✓ Asynchronous and unrelated to the current instruction
4. Only occurs when the CPU is idle

An 'illegal operation' during instruction execution is a common cause of what type of CPU event?

1. 1. External Interrupt
2. 2. System Call
3. 3. Internal Exception
4. 4. Timer Overflow

An 'illegal operation' during instruction execution is a common cause of what type of CPU event?

1. External Interrupt
2. System Call
3. ✓ Internal Exception
4. Timer Overflow

A page fault, which occurs when a program tries to access memory that is not currently loaded into RAM, is an example of:

1. 1. An external interrupt
2. 2. An asynchronous event
3. 3. An internal exception
4. 4. A clock signal

A page fault, which occurs when a program tries to access memory that is not currently loaded into RAM, is an example of:

1. An external interrupt
2. An asynchronous event
3. ✓ An internal exception
4. A clock signal

What does it mean for an internal exception to be 'synchronous'?

It means the exception is directly caused by the specific instruction currently being executed.

What does it mean for an external interrupt to be 'asynchronous'?

It means the interrupt is not tied to the current instruction being executed and can occur at any time.

Give an example of an I/O device that might trigger an external interrupt.

A keyboard, network card, or disk drive could trigger an external interrupt when they have data ready or require attention.