1. What are the difference between program counter and stack pointer?
Ans: Stack pointer is a register that is used to store the address of last program executed by the stack and program counter stores the address of the next program that is going to be executed from the memory.
2. What are the Addressing modes of 8085 microprocessor?
Ans: 1. Direct addressing mode.
2. Register addressing mode
3. Register indirect addressing mode.
4. Immediate addressing mode.
5. Implicit addressing mode.
3. What are the example of immediate addressing modes?
Ans: MVI , LXI
4. What are the examples of Indirect addressing mode?
Ans: MOV, LDAX
5. What is the difference between STAX and STA?
Ans: In STA, the content of accumulator are copied into the memory location but in STAX, The contents of the accumulator are copied into the memory location specified by the contents of the register pair.
6. What is the difference between SUB and SBB?
Ans: The SUB operation subtracts the contents of register from the contents of accumulator and stores the result in the accumulator and SBB subtract the content of register from the accumulator with borrow.
7. What is the difference between control signal and status signal?
Ans: Status signal is used to give the information regarding the operations performed by the microprocessor to the user while control signal is used to read data from input/output devices or memory.
8. What is interrupt in 8085 microprocessor?
Ans: Interrupt is the method of creating a temporary halt during program execution and allows peripheral devices to access the microprocessor.
9. What are the different types of operations in 8085 programming?
Ans: 1. Arithmetic operation.
2. Logical operations.
3. Conditional operation.
4. Machine control operation.
10. What is the difference between carry flag and auxiliary carry flag?
Ans: Carry flag is set when carry is generated in D7 bit while auxiliary carry is set when carry generated from D4 to D5.
11. What is the function of XCHG ?
Ans: XCHG exchange the contents of HL register pair with the contents of DE register pair.
12. What is the function of LDAX?
Ans: LDAX Rp is used to load the contents of the memory specified by the register pair to the accumulator.
13. What are the different types of flag register?
Ans: 1. Carry
2. Zero
3. Sign
4. Parity
5. Auxiliary carry.
14. What is the difference between LDA and LHLD?
Ans: LDA copies the contents of memory location to accumulator but LHLD Rp copies the contents of memory location specified by the register pair to the accumulator.
15. What is the bit size of 8085 and 8086 microprocessor?
Ans: 8085 is a 8 bit microprocessor and 8086 is a 16 bit microprocessor.
16. What is the difference between data bus and address bus?
Ans: Data bus is used to transfer data from one component to another in the microprocessor but address bus determines the memory location the microprocessor will read data data from or write data to.
Data bus is bidirectional but address bus is unidirectional.
17. What is the frequency range of 8085 microprocessor?
Ans: 3 MHz
18. What is DAA instruction?
Ans: The DAA ( DECIMAL ADJUST AFTER ADDITION) is used to add 8 bit BCD numbers. It assumes AL register as source and destination and doesn't require any operand.
19. What is the highest priority interrupts?
Ans: TRAP
20. What are different interrupts of 8085 microprocessor ?
Ans: TRAP, RST 7.5, RST 6.5, RST 5.5, and INTR.
21. What are maskable interrupts?
Ans: INTR, RST 7.5, RST 6.5, RST 5.5.
22. What is un maskable interrupt in 8085 ?
Ans: TRAP.
23. What is flag register?
Ans: Flag registers are special purpose registers which becomes either 0 or 1 after any arithmetic or logical operations depending upon the result.
24. Which bit is associated with sign flag?
As: Bit D7.
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