Skip to main content

Questions and Answers of 8085 Microprocessor (Part-II)

By
What are the different advances in semiconductor technology?

SSI - Small Scale Integration (10 transistors/chip)
MSI - Medium Scale Integration (10 to 100 transistors/chip)
LSI - Large Scale Integration (100 to 10,000 transistors/chip)
VLSI - Very Large Scale Integration (10,000 to 10^6 transistors/chip)
ULSI - Ultra Large Scale Integration (10^6 to 10^7 transistors/chip)
GSI - Giga Scale Integration (more than 10^7 transistors/chip)

What are the various functions of ALU?

The various functions performed by ALU are:
  • Addition
  • Subtraction
  • AND 
  • OR
  • EX-OR
  • Complement
  • Shift right
  • Shift left
  • Increment 
  • Decrement
What is the function of READY signal?

READY signal is used for synchronization of slower peripherals with the microprocessor. It senses whether the peripheral is ready or not to transfer the data. If the peripheral is not ready, the processor waits.

Why AD0 - AD7 lines are multiplexed?

The data bus (D0 - D7) and the lower half of address bus (A0 - A7) are multiplexed to reduce the number of external pins. During T1 of the machine cycle, lower 8-bit of memory or I/O address appear on bus. During T2 and T3 of the machine cycle, these lines are used as bidirectional data bus.

What is the function of ALE signal in 8085 microprocessor?

The data bus (D0 - D7) and the lower half of address bus (A0 - A7) are multiplexed. The lower half of address bus (A0-A7) is available only during T1 of the machine cycle. But this lower half of address bus is also necessary during T2 and T3 of the machine cycle. So it is necessary to latch the lower half of an address in T1 of the machine cycle so that it is available throughout the machine cycle. This important function of latching is done by external latch and ALE signal.

What is the function of IO/M, S0 and S1 signals in 8085 microprocessor?

These three signals are status signals. IO/M indicates whether IO operations or memory operation is to be carried out. If this signal is set, IO operation is carried out and if it is reset, memory operation is carried out. S0 and S1 indicates the type of machine cycle.

What is the function of HOLD and HLDA signals in 8085?

HOLD signal indicates that another processor is requesting for the use of address bus, data bus and control bus. HLDA signal is used to acknowledge HOLD request.

What is the special function of AND instruction?

AND instruction is used to clear a bit in a binary number. This process is called masking.

What is the special function of OR instruction?

OR instruction is used to set a bit in a binary number.

What is the special function of XOR instruction?

XOR instruction is used to invert or complement a bit in a binary number.
Labels:

Comments

Post a Comment

Popular posts from this blog

Program to pack the two unpacked BCD numbers

By
Statement: Pack the two unpacked BCD numbers stored in memory locations 2000H and 2001H and store the result in memory location 2002H. The least significant digit is stored at 2000H. Example: (2000H) = 04H (2001H) = 09H Result = (2002H) = 94H Program: LDA 2001H                        ; Obtain the most significant BCD digit RLC                                    ; Rotate left  RLC                                    ; Rotate left  RLC                                    ; Rotate left  RLC                                    ; Rotate left...
Post a Comment
Read more

Program to exchange the contents of two memory locations

By
Statement: Exchange the contents of memory locations 2000H and 2001H. Example:  Initially, (2000H) = 34H (2001H) = 20H After exchanging, (2000H) = 20H (2001H) = 34H Program 1 using direct addressing instructions: LDA 2000H               ; Get the contents of location 2000H into accumulator MOV B, A                  ; Move the contents of accumulator into register B LDA 2001H                ; Get the contents of location 2001H into accumulator STA 2000H                 ; Store the contents of accumulator into location 2000H MOV A, B                  ; Move the contents of register B into accumulator STA 2001H                 ; Store the contents of accumulator into location 2001H HLT  ...
Post a Comment
Read more

Stack Operations Instructions (Part-II) - SPHL and XTHL

By
SPHL: This instruction copies the contents of HL register pair to the stack pointer (SP). It means that the stack pointer will now point to the memory location whose address was given in the HL register pair. No flags are affected. It is a one byte instruction. Register addressing mode is used. Example: If HL = 2030H, then SPHL ; This instruction will copy 2030H into SP. So SP will point to the memory location 2030H. XTHL: This instruction exchanges the contents of the memory location pointed by stack pointer with the contents of the L register and the contents of the next memory location with the contents of H register. This instruction does not alter the contents of the stack pointer. No flags are affected. It is a one byte instruction. Register Indirect addressing mode is used. Example: If HL = 5601H, SP = 2000H, (2000H) = 30H and (2001H) = 20H, then XTHL ; This instruction will exchange the contents of the memory location 2000H i.e. 3...
Post a Comment
Read more