microprocessor viva/interview questions

1. What are the flags in 8086? – In 8086 Carry flag, Parity flag, Auxiliary carry flag, Zero flag, Overflow flag, Trace flag, Interrupt flag, Direction flag, and Sign flag. 
2. What are the various interrupts in 8086? – Maskable interrupts, Non-Maskable interrupts.
3. What is meant by Maskable interrupts? – An interrupt that can be turned off by the programmer is known as Maskable interrupt.
4. What is Non-Maskable interrupts? – An interrupt which can be never be turned off (ie.disabled) is known as Non-Maskable interrupt.
5. Which interrupts are generally used for critical events? – Non-Maskable interrupts are used in critical events. Such as Power failure, Emergency, Shut off etc.,
6. Give examples for Maskable interrupts? – RST 7.5, RST6.5, RST5.5 are Maskable interrupts
7. Give example for Non-Maskable interrupts? – Trap is known as Non-Maskable interrupts, which is used in emergency condition.
8. What is the Maximum clock frequency in 8086? – 5 Mhz is the Maximum clock frequency in 8086.
9. What are the various segment registers in 8086? – Code, Data, Stack, Extra Segment registers in 8086.
10. Which Stack is used in 8086? – FIFO (First In First Out) stack is used in 8086.In this type of Stack the first stored information is retrieved first.
11. What are the address lines for the software interrupts? -
    

    RST 0	0000 H
    RST1	0008 H
    RST2	0010 H
    RST3	0018 H
    RST4	0020 H
    RST5	0028 H
    RST6	0030 H
    RST7	0038 H

12. What is SIM and RIM instructions? – SIM is Set Interrupt Mask. Used to mask the hardware interrupts. RIM is Read Interrupt Mask. Used to check whether the interrupt is Masked or not.
13. Which is the tool used to connect the user and the computer? – Interpreter is the tool used to connect the user and the tool.
14. What is the position of the Stack Pointer after the PUSH instruction? – The address line is 02 less than the earlier value.
15. What is the position of the Stack Pointer after the POP instruction? – The address line is 02 greater than the earlier value.
16. Logic calculations are done in which type of registers? – Accumulator is the register in which Arithmetic and Logic calculations are done.
17. What are the different functional units in 8086? – Bus Interface Unit and Execution unit, are the two different functional units in 8086.
18. Give examples for Micro controller? – Z80, Intel MSC51 &96, Motorola are the best examples of Microcontroller.
19. What is meant by cross-compiler? – A program runs on one machine and executes on another is called as cross-compiler.
20. What are the address lines for the hardware interrupts? -
    

    RST 7.5	003C H
    RST 6.5	0034 H
    RST 5.5	002C H
    TRAP	0024 H

21. Which Segment is used to store interrupt and subroutine return address registers? – Stack Segment in segment register is used to store interrupt and subroutine return address registers.
22. Which Flags can be set or reset by the programmer and also used to control the operation of the processor? – Trace Flag, Interrupt Flag, Direction Flag.
23. What does EU do? – Execution Unit receives program instruction codes and data from BIU, executes these instructions and store the result in general registers.
24. Which microprocessor accepts the program written for 8086 without any changes? – 8088 is that processor.
25. What is the difference between 8086 and 8088? – The BIU in 8088 is 8-bit data bus & 16- bit in 8086.Instruction queue is 4 byte long in 8088and 6 byte in 8086.