I am aware that during addition/subtraction in the accumulator, if a 9-bit value is resulted the carry bit is set, but what if this is used:
mov A,-200
-200 is a 9-bit value in 2's compliment form. what's going to happen if I move it to accumulator? Is the extra bit going to drop off or go set the carry?
there is no MOV instruction with an 8-bit target which takes a 9-bit immediate operand!
I can think of no 8051 instruction that takes a 9-bit immediate operand.
MOV DPTR, #immediate
Takes a 16-bit immediate operand - so it could accommodate a 9-bit value.
But you're right - there's nothing that takes an actual 9-bit operand.