Cisco Systems Interview Question Bank – Part 4

Cisco Systems Interview Question Bank continued from Part 3

Q : What is the function of ALE in 8085?

A : ALE stands for Address Latch Enable. In 8085 microprocessor, there are 16 address lines for 16 bit memory location. Of these 16 bits,  higher order 8 bits are dedicated only for carrying the memory address. But, the lower order 8 bits are multiplexed with data lines to carry either address/data bits. The control signal ALE is used by 8085 to indicate whether these multiplexed 8 bits carries lower 8 address bits (when ALE=1) or data bits (when ALE=0). In short, when ALE=1, address is latched from the multiplexed bus and when ALE=0, address bus is disabled and data bus is enabled.

Q : What is the difference between circuit switching and packet switching.

A : Circuit switching is a type of method for implementing a telecommunication network in which a dedicated path or physical connection is established before transmission of data. Dedicated connection allows full-duplex, fast, safe and reliable transmission of data. After the data transfer, the path is released. Example – voice communication (telephone etc.).

Packet switching is a digital networking method for (half-duplex) communication in which data is divided into small segments (called packets) which are transmitted over a medium that is shared between parties in a network. Example – data communication (internet etc.).

Q : What do you mean by ARP?

A : ARP (Address Resolution Protocol) is a protocol used by IP at Network layer that is used to convert an IP address into a physical address such as Ethernet address. When a host wants to obtain physical address, it broadcasts an ARP request on to the TCP/IP. The host on the network that has the physical address asked, replies with the address. The four types of ARP messages that may be sent by ARP are – ARP request, ARP reply, RARP (Reverse ARP) request and RARP reply.

The above questions are related to concepts of core ECE domains. But, apart from questions from core domains, some important concepts of Computer Science (CS) are also asked during interviews. Following are some of the questions from CS which were asked in recent times…

  1. Binary sort, insertion sort and their difference.
  2. Insertion of node in linked list.
  3. Write a macro to set the nth bit.
  4. What is the boundary problem in allocation of size of structures?
  5. Write a program to reverse a linked list.
  6. Can you use a variable in a file using extern which is defined as both static and global in base file?
  7. When we declare union in C, how is the size of union allocated in the memory?
  8. Questions on balanced trees.
  9. What is the worst case complexity of Quick sort?

Hope this helps you. Best of luck!

Gautam Vashisht