 All systems have at least 1 IOP.On the 4080, this first IOP was called the Basic Multiplexer Channel, or BMC, and the 4080 front panel provides for controlling both the CPU and the BMC.The entry level 415x and 4x6x systems have their first IOP (Integral Multiplexer Channel, or IMC) integrated into the Nucleus firmware, and thus I/O operations on the IMC did have some impact on CPU performance, although the 4x6x systems could have additional external IOPs added too.