8085 Microprocessor MCQ

21. While using a frequency counter for measuring frequency, two modes of measurement are possible.

1. Period mode
2. Frequency mode

There is a ‘cross-over frequency’ below which the period mode is preferred. Assuming the crystal oscillator frequency to be 4 MHz the crossover frequency is given by

1. 8 MHz
2. 2 MHz
3. 2 kHz
4. 1 kHz

22. In a 8085 microprocessor system with memory-mapped I/O, which of the following is true?

1. Devices have 8-bit‘address line
2. Devices are accessed using IN and OUT instructions
3. There can be maximum of 256 input devices and 256 output devices
4. Arithmetic and logic operations can be directly performed with the I/O data

23. Consider the following statements:

Arithmetic Logic Unit (ALU)

1 . Performs arithmetic operations.
2. Performs comparisons.
3. Communicates with I/O devices.
4. Keeps watch on the system.

Which of these statements are correct?

1. 1, 2, 3 and 4
2. 1,2 and 3 only
3. 1 and 2 only
4. 3 and 4 only

24. Ready pin 0f microprocessor is used

1. to indicate that the microprocessor is ready to receive inputs
2. to indicate that the microprocessor is ready to receive outputs
3. to introduce wait state
4.  to provide direct memory access

25. A bus connected between the CPU and the main memory that permits transfer of information between main memory and the CPU is known as

1. DMA bus
2. Memory bus
3. Address bus
4. Control bus

26. The operations executed by two or more control units are referred as

1. Micro-operations
2. Macro-operations
3. Multi-operations
4. Bi control-operations

27. Consider the following registers:

1. Accumulator and flag register
2. B and C registers
3. D and E registers
4. H and L registers

Which of these 8-bit registers of 8085 μP can be paired together to make a 16-bit register?

1. (a) 1, 3 and 4
2. 2, 3 and 4
3. 1, 2 and 3
4. 1, 2 and 4

28. The first microprocessor to include virtual memory in the Intel microprocessor family is

1. 80286
2. 80386
3. 80486
4. Pentium

29. Program counter in a digital computer

1. counts the numbers of programs run in the machine ,
2. counts the number of times a subroutine is called
3. counts the number of times the loops are executed
4. points the memory address of the current or the next instruction to be executed

30. Assuming LSB is at position 0 and MSB at position 7, which bit positions are not used (undefined) in Flag Register of an 8085 microprocessor?

1. 1, 3, 5
2. 2, 3, 5
3. 1, 2, 5
4. 1, 3, 4

31. At the beginning of a fetch cycle, the contents of the program counter are

1. incremented by one
2. transferred to address bus
3. transferred to memory address register
4. transferred to memory data register

32. Each instruction in an assembly language program has the following fields

1. Label field
2. Mnemonic field
3. Operand field
4. Comment field

What is the correct sequence of these fields?

1. 1, 2, 3 and 4
2. 2, 1, 4 and 3
3. 1,3, 2 and 4
4. 2, 4, 1 and 3

33. The relation among IC (lnstruction Cycle), FC (Fetch Cycle) and EC (Execute Cycle) is

1. IC = FC − EC
2. IC = FC+ EC
3. IC= FC + 2EC
4. EC = IC+FC

34. When a peripheral is connected to the microprocessor in input/output mode, the data transfer takes place between

1. any register and I/O device
2. memory and I/O device
3. accumulator and I/O device
4. HL registerand I/O device

35. While execution of I/O instruction takes place, the 8-bit address of the port is placed on

1. lower address bus
2. higher address bus
3. data bus
4. lower as well as higher-order address bus

36. The length of a bus cycle in 8086/8088 is four clock cycles, T₁, T₂, T₃, T₄ and an indeterminate number of wait state clock cycles denoted by T_W. The wait states are always inserted between

1. T₁ and T₂
2. T₂ and T₃
3. T₃ and T₄
4. T₄ and T₁

37. Which one of the following circuits transmits two messages simultaneously in one direction?

1. Duplex
2. Diplex
3. Simplex
4. Quadruplex

38. A microprocessor is ALU

1. and control unit on a single chip
2. and memory on a single chip
3. register unit and I/O device on a single chip
4. register unit and control unit on a single chip

39. In Intel 8085 microprocessor, ALE signal is made high to

1. Enable the data bus to be used as low order address bus
2. To latch data D₀— D₇ from the data bus
3. To disable data bus
4. To achieve all the functions listed above

40. Output of the assembler in machine codes is referred to as

1. Object program
2. Source program
3. Macro instruction
4. Symbolic addressing