Addressing mode in 8086
Well, x86 hasn't the simplest instruction format... And similar addressing modes can be named differently for different CPUs.
In most CPUs (particularly RISCs and simple 8bits CPUs), there is only zero or one memory operation for data, so each instruction can be binned in one addressing mode or another.
For CISC CPUs it can be a bit more complex, for example x86 supports writing an immediate value to memory without going through a register.
Intel manuals don't really name the addressing mode for each instruction, because it's too complex, there are instead acronyms to describe operands such as imm8,imm16,r/m8,r/m16...
So your &quot;MOV AH,0x09h&quot; is probably &quot;immediate&quot; addressing, Intel describes it as &quot;MOV r8,imm8&quot; : 8bit register as destination to 8bit immediate.