8085 microprocessor questions1. What are the various registers in 8085? - Accumulator

register, Temporary register, Instruction register, Stack Pointer, Program Counter are the various registers in 8085 .

2. In 8085 name the 16 bit registers? - Stack pointer and Program counter all have 16 bits.

3. What are the various flags used in 8085? - Sign flag, Zero flag, Auxillary flag, Parity flag, Carry flag.

4. What is Stack Pointer? - Stack pointer is a special purpose 16-bit register in the Microprocessor, which holds the address of the top of the stack.

5. What is Program counter? - Program counter holds the address of either the first byte of the next instruction to be fetched for execution or the address of the next byte of a multi byte instruction, which has not been completely fetched. In both the cases it gets incremented automatically one by one as the instruction bytes get fetched. Also Program register keeps the address of the next instruction.

6. Which Stack is used in 8085? - LIFO (Last In First Out) stack is used in 8085.In this type of Stack the last stored information can be retrieved first.

7. What happens when HLT instruction is executed in processor? - The Micro Processor enters into Halt-State and the buses are tri-stated.

8. What is meant by a bus? - A bus is a group of conducting lines that carriers data, address, & control signals.

9. What is Tri-state logic? - Three Logic Levels are used and they are High, Low, High impedance state. The high and low are normal logic levels & high impedance state is electrical open circuit conditions. Tri-state logic has a third line called enable line.

10. Give an example of one address microprocessor? - 8085 is a one address microprocessor.

11. In what way interrupts are classified in 8085? - In 8085 the interrupts are classified as Hardware and Software interrupts.

12. What are Hardware interrupts? - TRAP, RST7.5, RST6.5,

RST5.5, INTR.

13. What are Software interrupts? - RST0, RST1, RST2, RST3, RST4, RST5, RST6, RST7.

14. Which interrupt has the highest priority? - TRAP has the highest priority.

15. Name 5 different addressing modes? - Immediate, Direct, Register, Register indirect, Implied addressing modes.

16. How many interrupts are there in 8085? - There are 12 interrupts in 8085.

17. What is clock frequency for 8085? - 3 MHz is the maximum clock frequency for 8085.

18. What is the RST for the TRAP? - RST 4.5 is called as TRAP.

19. In 8085 which is called as High order / Low order Register? - Flag is called as Low order register & Accumulator is called as High order Register.

20. What are input & output devices? - Keyboards, Floppy disk are the examples of input devices. Printer, LED / LCD display, CRT Monitor are the examples of output devices.

21. Can an RC circuit be used as clock source for 8085? - Yes, it can be used, if an accurate clock frequency is not required. Also, the component cost is low compared to LC or Crystal.

22. Why crystal is a preferred clock source? - Because of high stability, large Q (Quality Factor) & the frequency that doesn’t drift with aging. Crystal is used as a clock source most of the times.

23. Which interrupt is not level-sensitive in 8085? - RST 7.5 is a raising edge-triggering interrupt.

24. What does Quality factor mean? - The Quality factor is also defined, as Q. So it is a number, which reflects the lossness of a circuit. Higher the Q, the lower are the losses.

25. What are level-triggering interrupt? - RST 6.5 & RST 5.5 are level-triggering interrupts.

x86 interview questionsThese interview questions test the knowledge of x86 Intel architecture and 8086 microprocessor specifically.

1. What is a Microprocessor? - Microprocessor is a program-controlled device, which fetches the instructions from memory, decodes and executes the instructions. Most Micro Processor are single- chip devices.

2. Give examples for 8 / 16 / 32 bit Microprocessor? - 8-bit Processor - 8085 / Z80 / 6800; 16-bit Processor - 8086 / 68000 / Z8000; 32-bit Processor - 80386 / 80486.

3. Why 8085 processor is called an 8 bit processor? - Because 8085 processor has 8 bit ALU (Arithmetic Logic Review). Similarly 8086 processor has 16 bit ALU.

4. What is 1st / 2nd / 3rd / 4th generation processor? - The processor made of PMOS / NMOS / HMOS / HCMOS technology is called 1st / 2nd / 3rd / 4th generation processor, and it is made up of 4 / 8 / 16 / 32 bits.

5. Define HCMOS? - High-density n- type Complimentary Metal Oxide Silicon field effect transistor.

6. What does microprocessor speed depend on? - The processing speed depends on DATA BUS WIDTH.

7. Is the address bus unidirectional? - The address bus is unidirectional because the address information is always given by the Micro Processor to address a memory

location of an input / output devices.

8. Is the data bus is Bi-directional? - The data bus is Bi-directional because the same bus is used for transfer of data between Micro Processor and memory or input / output devices in both the direction.

9. What is the disadvantage of microprocessor? - It has limitations on the size of data. Most Microprocessor does not support floating-point operations.

10. What is the difference between microprocessor and microcontroller? - In Microprocessor more op-codes, few bit handling instructions. But in Microcontroller: fewer op-codes, more bit handling Instructions, and also it is defined as a device that includes micro processor, memory, & input / output signal lines on a single chip.

11. What is meant by LATCH? - Latch is a D- type flip-flop used as a temporary storage device controlled by a timing signal, which can store 0 or 1. The primary function of a Latch is data storage. It is used in output devices such as LED, to hold the data for display.

12. Why does microprocessor contain ROM chips? - Microprocessor contain ROM chip because it contain instructions to execute data.

13. What is the difference between primary & secondary storage device? - In primary storage device the storage capacity is limited. It has a volatile memory. In secondary storage device the storage capacity

is larger. It is a nonvolatile memory. Primary devices are: RAM / ROM. Secondary devices are: Floppy disc / Hard disk.

14. Difference between static and dynamic RAM? - Static RAM: No refreshing, 6 to 8 MOS transistors are required to form one memory cell, Information stored as voltage level in a flip flop. Dynamic RAM: Refreshed periodically, 3 to 4 transistors are required to form one memory cell, Information is stored as a charge in the gate to substrate capacitance.

15. What is interrupt? - Interrupt is a signal send by external device to the processor so as to request the processor to perform a particular work.

16. What is cache memory? - Cache memory is a small high-speed memory. It is used for temporary storage of data & information between the main memory and the CPU (center processing unit). The cache memory is only in RAM.

17. What is called “Scratch pad of computer”? - Cache Memory is scratch pad of computer.

18. Which transistor is used in each cell of EPROM? - Floating –gate Avalanche Injection MOS (FAMOS) transistor is used in each cell of EPROM.

19. Differentiate between RAM and ROM? - RAM: Read / Write memory, High Speed, Volatile Memory. ROM: Read only memory, Low Speed, Non Voliate Memory.

20. What is a compiler? - Compiler is used to translate the high-level language program into machine code at a time. It doesn’t require special instruction to store in a memory, it stores automatically. The Execution time is less compared to Interpreter.

21. Which processor structure is pipelined? - All x86 processors have pipelined structure.

22. What is flag? - Flag is a flip-flop used to store the information about the status of a processor and the status of the instruction executed most recently

23. What is stack? - Stack is a portion of RAM used for saving the content of Program Counter and general purpose registers.

24. Can ROM be used as stack? - ROM cannot be used as stack because it is not possible to write to ROM.

25. What is NV-RAM? - Nonvolatile Read Write Memory, also called Flash memory. It is also know as shadow RAM.

Intel interview questions

1. The following questions are used for screening the candidates during the first interview. The questions apply mostly to fresh college grads pursuing an engineering career at Intel.

1. Have you studied buses? What types?

2. Have you studied pipelining?

List the 5 stages of a 5 stage pipeline. Assuming 1 clock per stage, what is the latency of an instruction in a 5 stage machine? What is the throughput of this machine ?

3. How many bit combinations are there in a byte?

4. For a single computer processor computer system, what is the purpose of a processor cache and describe its operation?

5. Explain the operation considering a two processor computer system with a cache for each processor.

6. What are the main issues associated with multiprocessor caches and how might you solve them?

7. Explain the difference between write through and write back cache.

8. Are you familiar with the term MESI?

9. Are you familiar with the term snooping?

10. Describe a finite state machine that will detect three consecutive coin tosses (of one coin) that results in heads.

11. In what cases do you need to double clock a signal before presenting it to a synchronous state machine?

12. You have a driver that drives

a long signal & connects to an input device. At the input device there is either overshoot, undershoot or signal threshold violations, what can be done to correct this problem?

13. What are the total number of lines written by you in C/C++? What is the most complicated/valuable program written in C/C++?

14. What compiler was used?

15. What is the difference between = and == in C?

16. Are you familiar with VHDL and/or Verilog?

17. What types of CMOS memories have you designed? What were their size? Speed?

18. What work have you done on full chip Clock and Power distribution? What process technology and budgets were used?

19. What types of I/O have you designed? What were their size? Speed? Configuration? Voltage requirements?

20. Process technology? What package was used and how did you model the package/system? What parasitic effects were considered?

21. What types of high speed CMOS circuits have you

designed?

22. What transistor level design tools are you proficient with? What types of designs were they used on?

23. What products have you designed which have entered high volume production?

24. What was your role in the silicon evaluation/product ramp? What tools did you use?

25. If not into production, how far did you follow the design and why did not you see it into production?

A+ and basic PC questions1. What are the basic expansion card

types?ISA and PCI, ISA can be used only on XT, AT and ATX boards. The industry now considers ISA obsolete.

2. How do you clear CMOS password? Since CMOS is a special chip with its own battery, the best way to clear out a CMOS chip is to disconnect it from its power supply.

3. Where does the Real mode on the CPU come from? The original 8086, which only had 1 MB of memory. This megabyte is split into low memory for IRQ tables, application memory and high memory.

4. Where does CPU Enhanced mode originate from? Intel’s 80386 was the first 32-bit processor, and since the company had to backward-support the 8086. All the modern

Intel-based processors run in the Enhanced mode, capable of switching between Real mode (just like the real 8086) and Protected mode, which is the current mode of operation.

5. Name the processor lines of two major manufacturers? High-end: Intel - Pentium (II, III, 4), AMD - Athlon. Low-end: Intel - Celeron, AMD - Duron. 64-bit: Intel - Itanium 2, AMD - Opteron.

6. What’s the difference between L1 and L2 cache? Level 1 cache is internal to the chip, L2 is external.

7. What’s the speed and device maximum specs for Firewire? IEEE 1394 (Firewire) supports the maximum of 63 connected devices with speeds up to 400 Mbps.

8. Where’s MBR located on the disk? Main Boot Record is located in sector 0, track 0, head 0, cylinder 0 of the primary active partition.

9. What’s the maximum hard drive size for FAT16-based Windows system? 2 GB.

10. How many logical drives is it possible to fit onto a physical disk? Maximum of 24 logical drives. The extended partition can only have 23 logical drives.

11. WHat are * and ? when using them for wildcards in Windows? * - any characters, arbitrary amoung, ? - single character.

12. How does the browser know to go to a certain IP address when you enter a domain like google.com? It searches through local DNS cache,

if nothing is there, it queries the ISP’s DNS server.

Telecommunications interview questions

A well-known telecommunications company uses this pop quiz for oral and written examinations of applicants for engineering positions.

1. A 2MB PCM(pulse code modulation) has…

a) 32 channelsb) 30 voice channels & 1 signaling channel.c) 31 voice channels & 1 signaling channel.d) 32 channels out of which 30 voice channels, 1 signaling channel, & 1 synchronization channel.

Ans: c

2. Time taken for 1 satellite hop in voice communication is…

a) 1/2 secondb) 1 secondsc) 4 secondsd) 2 seconds

Ans: (a)

3. Max number of satellite hops allowed in voice communication is:

a) only oneb) more han onec) two hopsd) four hops

Ans: ©

4. What is the maximal decimal number that can be accommodated in a byte?

a) 128b) 256c) 255d) 512

Ans: ©

5. Conditional results after execution of an instruction in a micro processor is stored in…

a) registerb) accumulatorc) flag registerd) flag register part of PSW(Program Status Word)

Ans: (d)

6. Frequency at which VOICE is sampled is…

a) 4 KHzb) 8 KHzc) 16 KHzd) 64 KHz

Ans: (a)

7. Line of sight is…

a) Straight Lineb) Parabolicc) Tx & Rx should be visible to each otherd) none of the above

Ans: ©

8. Purpose of PC(Program Counter) in a MicroProcessor is…

a) To store address of TOS(Top Of Stack)b) To store address of next instruction to be executed.c) count the number of instructions.d) to store base address of the stack.

Ans: (b)

9. What action is taken when the processor under execution is interrupted by a non-maskable interrupt?

a) Processor serves the interrupt request after completing the execution of the current instruction.b) Processor serves the interrupt request after completing the current

task.c) Processor serves the interrupt request immediately.d) Processor serving the interrupt request depends upon the priority of the current task under execution.

Ans: (a)

10. The status of the Kernel is…

a) taskb) processc) not defined.d) none of the above.

Ans: (b)

11. What is the nominal voltage required in subscriber loop connected to local exchange?

a) +48 voltsb) -48 voltsc) 230 voltsd) 110 volts

12. To send a data packet using datagram , connection will be established…

a) before data transmission.b) connection is not established before data transmission.c) no connection is required.d) none of the above.

Ans: ©

13. Word alignment is…

a) aligning the address to the next word boundary of the machine.b) aligning to an even boundary.c) aligning to a word boundary.d) none of the above.

Ans: (a)

14. When a C function call is made, the order in which parameters

passed to the function are pushed into the stack is…

a) left to rightb) right to leftc) bigger variables are moved first than the smaller variales.d) smaller variables are moved first than the bigger ones.e) none of the above.

Ans: (b)

15. What is the type of signaling used between two exchanges?

a) inbandb) common channel signalingc) any of the aboved) none of the above.

Ans: (a)

16. Buffering is…

a) the process of temporarily storing the data to allow for small variation in device speedsb) a method to reduce cross talksc) storage of data within transmitting medium until the receiver is ready to receive.d) a method to reduce routing overhead.

Ans: (a)

17. Memory allocation of variables declared in a program is…

a) allocated in RAM.b) allocated in ROM.c) allocated on stack.d) assigned to registers.

Ans: ©

18. A software that allows a personal computer to pretend as a computer terminal is …

a) terminal adapterb) bulletin boardc) modem

d) terminal emulation

Ans: (d)