TRAP flag in 8086 is used for

• Trap Flag (T) in 8086 is used for on-chip debugging.
• Setting the trap flag puts the microprocessor into a single step mode for debugging.
• In single stepping, the microprocessor executes an instruction and enters into a single step ISR.
• If the TRAP flag is set (1), the CPU automatically generates an internal interrupt after each instruction, allowing a program to be inspected as it executes instruction by the instruction.
• If the TRAP is reset (0), no function is performed.

8086 has 6 status flags which are:

Carry, Parity, Auxiliary Carry, Zero, Sign, and Overflow

8086 also has three control flags which are:

Direction, Interrupt Enable, and TRAP

TRAP flag is present in 8086 but not in 8085.