The 8086 Microprocessor

1. What do you mean by Addressing modes?

The different ways that a microprocessor can access data are referred to as addressing
modes.

2. What is meant by Vectored interrupt?

When the external device interrupts the processor, processor has to execute interrupt service routine for servicing the interrupt. If the internal control circuit of the processor produces a CALL to a predefined memory location which is the starting address of interrupt service routine, then that address is called Vector address and such interrupts are called vector interrupts.

3. Name the hardware interrupts of 8086.

1. Divide by zero interrupt (Type 0)
2. Single step interrupt (Type 1)
3. Non Maskable interrupt (Type 2)
4. Breakpoint interrupt (Type 3)
5. Overflow interrupt ( Type 4)

4. What are called as assembler directives? Give two examples.

There are some instructions in the assembly language which are not a part of processor instruction set. These instructions are instructions to the assembler, linker and loader. These are referred to as pseudo-operations or as assembler derivatives. Example: ALIGN, ASSUME.

5. What address in the interrupt vector table are used for a Type-2 interrupt in 8086?

008H (CS base address) and 00CH (IP offset) are the addresses in the interrupt vector table are used for a Type-2 interrupt in 8086.

6. Why do we use Macros?

Macro is a group of instruction. The macro assembler generates the code in the program each time where the macro is called. Macros are defined by MACRO & ENDM directives. Creating macro is similar to creating new opcodes that can be used in the program
INIT MACRO
MOV AX,
data MO V DS
MOV ES, AX
ENDM

7. What is BIOS function call in 8086 μ p?

With the software interrupts you can call the desired routines from many different programs in a system.eg. BIOS in IBM PC. The IBM PC has in its ROM collection of routines, each performing some specific function such as reading character from keyboard, writing character to CRT. This collection of routines referred to as Basic Input Output System or BIOS. The BIOS routines are called with INT instructions.

8. What are the general purposes registers in 8086?

AX, BX, CX, DX are the general purpose registers in 8086.

9. Give the importance of the assembler directive EVEN.

The assembler derivative EVEN aligns next variable or instruction to even byte.

10 Name the registers available in 8086.

(i) General purpose registers
(ii) Segment registers
(iii) Pointers and index registers
(iv) Flag Registers.

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