Microprocessors - Question and Answer - 2

6. What are the various registers in 8085 ?
The 8085 has six general-purpose registers to store 8-bit data, these are identified as- B, C, D, E, H, and L. These can be combined as register pairs – BC, DE, and HL, to perform some 16-bit operation. These registers are used to store or copy temporary data, by using instructions, during the execution of the program. Accumulator register, Temporary register, Instruction register, Stack Pointer, Program Counter are the various registers in 8085

6. What are the various registers in 8085 ?
The 8085 has six general-purpose registers to store 8-bit data, these are identified as- B, C, D, E, H, and L. These can be combined as register pairs – BC, DE, and HL, to perform some 16-bit operation. These registers are used to store or copy temporary data, by using instructions, during the execution of the program. Accumulator register, Temporary register, Instruction register, Stack Pointer, Program Counter are the various registers in 8085

7. How many interrupts are there in 8085 ?
There are 12 interrupts in 8085.

8. Briefly explain the steps involved in a fetch cycle?
This is the advanced Microprocessor Interview Questions asked in an interview. Fetch cycle is time taken to retrieve an operation code from a specific location in memory.
General fetch cycles consist of 3T states.
In first T state, memory address stored in program counter is sent to memory.
In the second T state, contents of the specified memory location from the program counter are read.
In 3rd T state, the operation code is sent to instruction register for execution via a data bus.
In case of memories with slow execution speed, there is provision for WAIT cycles.

9. 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. The differences between the two are as follows: 8086 has 16-bit data bus whereas 8088 has 8-bit data bus. ... The Instruction Queue of 8086 is 6-bit long and that of 8088 is 4-bit long. 8086 has Bus High Enable (BHE) pin.

10. 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.
Because of the way atoms are aligned and give rise to resonance frequencies. These frequencies are extremely stable.There are 12 interrupts in 8085.

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