Question

A laser printer produces up to 20 pages per minute, where a page consists of 4000 characters. The system uses interrupt-driven I/O, where processing each interrupt takes 50 microseconds. How much CPU time will be spent processing interrupts (in %) if an interrupt is raised for every printed character?

Answer 1

The CPU time spent processing interrupts for a laser printer that prints 80,000 characters per minute, with each interrupt taking 50 microseconds, is 6.67% of the total CPU time.

Step-by-step explanation:

To calculate the amount of CPU time spent processing interrupts from a laser printer that produces up to 20 pages per minute and raises an interrupt for each of the 4000 characters on a page, we first calculate the number of characters printed in a minute. Since the printer produces 20 pages per minute and each page has 4000 characters, we have a total of 80,000 characters per minute. Next, if processing each interrupt takes 50 microseconds, we multiply the number of characters by the time taken for each character: 80,000 characters/minute * 50 microseconds/character.

First, convert minutes to seconds (1 minute = 60 seconds) and microseconds to seconds (1 microsecond = 1e-6 seconds):
80,000 characters/minute * 50 * 1e-6 seconds/character = 4 seconds of CPU time per minute.

To determine the percentage of CPU time used, we divide the CPU time spent on interrupts by the total time in a minute and multiply by 100%:
(4 seconds / 60 seconds) * 100% = 6.67% of CPU time spent processing interrupts.