1. How many bits processor is 8086?
Answer
16-bit processor.
2. What are the sizes of data bus and address bus in 8086?
Answer
16-bit data bus, and 20-bit address bus.
3. What is the maximum addressable memory of 8086?
Answer
1MByte, because 20-bit address bus.
4. How are 32-bit addresses stored in 8086?
Answer
32-bit addresses are stored in "SEGMENT:OFFSET" format. SEGMENT and OFFSET are 16-bit values.
ADDRESS = (SEGMENT* 16) + OFFSET
5. What are the 16-bit registers that are available in 8086?
Answer
The following are the 16-bit registers that are available in 8086.
8 general purpose registers:
AX - Accumulator Register
Bx - Base Register
CX - Count Register
DX - Data Register
SP - Stack Pointer
BP - Base Pointer
SI - Source Index
DI - Destination Index
4 segment registers:
CS - Code Segment
DS - Data Segment
SS - Stack Segment
ES - Extra Segment
Others:
IP - Instruction Pointer
Flag register
6. What are the different types of address modes available in 8086?
Answer
Implied - the data value/data address is implicitly associated with the instruction.
Register - references the data in a register or in a register pair.
Immediate - the data is provided in the instruction.
Direct - the instruction operand specifies the memory address where data is located.
Register indirect - instruction specifies a register containing an address, where data is located. This addressing mode works with SI, DI, BX and BP registers.
Based - 8-bit or 16-bit instruction operand is added to the contents of a base register (BX or BP), the resulting value is a pointer to location where data resides.
Indexed - 8-bit or 16-bit instruction operand is added to the contents of an index register (SI or DI), the resulting value is a pointer to location where data resides.
Based Indexed - the contents of a base register (BX or BP) is added to the contents of an index register (SI or DI), the resulting value is a pointer to location where data resides.
Based Indexed with Offset - 8-bit or 16-bit instruction operand is added to the contents of a base register (BX or BP) and index register (SI or DI), the resulting value is a pointer to location where data resides.
7. How many flags are available in flag register? What are they?
Answer
9 flags are available, they are:
Overflow Flag
Direction Flag
Interrupt-enable Flag
Trace/Trap Flag
Sign Flag
Zero Flag
Auxiliary carry Flag
Parity Flag
Carry Flag
8. Explain the functioning of IP (instruction pointer).
Answer
IP always points to next instruction to be executed. Offset address is relative to CS (which points at the segment containing the current program). The next instruction address is obtained using IP.
9. What are the various types of interrupts present in 8086?
Answer
INTR - maskable hardware interrupt
NMI - non-maskable interrupt
Software interrupts
10. How many segments are present in 8086? What are they?
Answer
4 segments are available in 8086. They are:
Code segment
Data segment
Extra segment
Stack segment
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