Interview Question Answers on 8086 Microprocessor

Here are some list of Interview Question Answers on 8086 Microprocessor. I believe this set of questions with solution will helpful for entry level position/academic interview. 8086 is one of famous microprocessor architecture. 8086 is 16-bit microprocessor designed by Intel which gave rise to X86 architecture. The work on 8086 design started in 1976 and chip was introduced to market in the summer of 1978.

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Which microprocessor accepts the program written for 8086 without any changes?

8088 Microprocessor.

How many instructions can be executed per second in 8086/8088?

2.5 Millions Instructions can be executes.

What are the features of Intel 8086?

Released by Intel in 1978 produced from 1978-1990. A 16-bit Microprocessor chip max. CPU clock rate 5MHz to 10MHz. Instruction Set: X86-16 package: 40-Pin DIP, 16-bit Arithmetic Logic Unit, 16-bit data bus (8088 has 8-bit data bus) 20-bit address bus. In 8086, bytes at even addresses come in on the low half of the data bus (bit 0-7) and bytes at odd address come in on upper half of the data bus (bits 8-15). The 8086 can read a 16-bit word at an even address in one operation and at an odd address in either case. The least significant byte of a word on an 8086 family microprocessor is at the lower address.

What is Logical Address?

A memory address on the 8086 consist of two numbers usually written in hexadecimal and separated by colon representing segment and the offset. The combination of segment and offset is referred to as a logical address. In short Logical Address = Segment : Offset.

What is Effective Address?

In general, memory accesses take the form of the following example: MOV ax,[Base Reg. + Index Reg. + Constant]. This example copies a word size value into the register Ax. Combined the three parameters in brackets determine what is called the effective address, which is simply the offset referenced by the instruction.

What is data and address size in 8086?

The 8086 can operate on either 8-bit or 16-bit data. The 8086 uses 20-bit address to access memory and 16-bit address to access I/O devices.

Write the flags in 8086?

  • Carry Flag (CF)
  • Overflow Flag (OF)
  • Parity Flag (PF)
  • Trace Flag (TF)
  • Auxiliary Flag (AF)
  • Interrupt Flag (IF)
  • Zero Flag (ZF)
  • Direction Flag (DF)
  • Sign Flag (SF)

Explain the function of M/IO in 8086?

The signal M/IO is used to differentiate memory address and IO Address. When the processor is accessing memory locations M/IO is asserted high and when it is accessing I/O mapped devices, then it asserts low.

What is the function of BIU?

The BIU contains the circuit for physical calculations and a pre-coding instruction byte queue and it makes the bus signal available for external interfacing of devices.

What is the function of EU?

The EU contains the register set of 8086 except segment register and IP. It has 16-bit ALU able to perform arithmetic and logic operations.

What is the size of instruction queue in 8086?

The queue length depends on the fetching speed and execution speed. Sometime queue may be restricted due to the space available on the CPU chip.

What are the Interrupts of 8086?

The interrupts of 8086 are INTR and NMI. The INTR is general maskable interrupt and NMI is non-maskable interrupt.

What is the position of stack pointer after the PUSH instruction?

The address is 02 less than the earlier value.

What is the position of stack pointer after POP instruction?

The address is 02 greater than the earlier Value.

List some of the features of INTEL8259 (Programmable Interrupt Controller)

  • It manages 8 interrupt request
  • The interrupt vector addresses are programmable
  • The priorities of interrupts are programmable
  • The interrupt can be masked or unmasked individually

How clock signal is generated in 8086?

The 8086 does not have on-chip clock generation circuit. Hence the clock generator chip, 8284 is connected to the CLK pin of 8086. The clock signal supplied by 8284 is divided by three for internal use. The maximum internal clock frequency of 8086 is 5 MHz.

About Umesh Lokhande

Umesh Lokhande holds a Master degree in Scientific Instrumentation from University of Applied Sciences Jena, Germany. and has previously worked at Orbotech, Alere Technologies etc. Umesh is also a founder and first author of BINARYUPDATES.COM

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