View All num of num See all Photos Cisco Systems This employer has taken extra steps to respond to reviews and provide job seekers with accurate company information, photos, and reviews. Interested for your company?Learn More. www.cisco.com www.cisco.com Work in HR? Unlock Free Profile Overview Reviews Salaries Interviews Jobs Photos Benefits 5.4k Reviews 12k Salaries 1.2k Interviews 3.1k Jobs Follow Add Review or Salary Follow Add Review or Salary Cisco Systems 5427 Interview Question Software Engineer Interview Boxborough, MA Cisco Systems Given 3 systems: system 1 reaches 0xFF, then system 2 increment by 1. Everytime system 2 increments, system 3 would fetch the package. When can there be a problem? What is the problem with this system? How can we fix this? Tags: See more , See less 8 Answer Add Tags Flag as Inappropriate Thank you! Your feedback has been sent to the team and we'll look into it. Oops! We're sorry but your feedback didn't make it to the team. Your input is valuable to us — would you mind trying again? Send Answer Interview Answer 1 Answer ▲ 0 ▼ Problem:system 2 counter can overflow (that answers what and when) or will overflow eventually (if its also 1 byte that after 256*256)Solution:Well, if its interrupt based (i.e.interrupt for every tick), we put boundaries i.e system2 == 0xFF , reset system2 counterif its polling, its possible that when we check , system2 could have increased by 'k' amount (where k=0,1,2,....,0xFF), in that case if system1 increments periodically, we can time-bound our polling to a multiple of 256*m periods and fetch 'm' packages, making sure that 0xFF falls on that boundary. RTOS will be required to guarantee our task a CPU slice every 256*m intervalsif its random, interrupt polling is better, else we have to check for overflow,i.e at time 't' , system2 = c1and time 't+k', k>0 , system2 = c2,then if c2 < c1 => overflow and total ticks is (0xff - c2) + c1Anyway, more you think, you can get even better approaches and if you know which OS and CPU is being used , it can help too R on Jun 24, 2014 Flag as Inappropriate Thank you! Your feedback has been sent to the team and we'll look into it. Oops! We're sorry but your feedback didn't make it to the team. Your input is valuable to us — would you mind trying again? Send Add Answers or Comments To comment on this, Sign In or Sign Up.