@wizzwizz4 >proprietary software >your CPU (with its proprietary firmware and proprietary logic circuitry) is malicious
My CPU is all hardware, as circuitry is hardware and the microcode in ROM is hardware.

Malicious circuits are rare due to the physical evidence created.

As far as I can tell, the proprietary software intel previously provided for my CPU and motherboard is malicious, but I don't run that.

Firmware is microprocessor instructions in an external ROM chip that can be trivially cut out and replaced - if it can be updated with software, it's software, otherwise it's hardware, aside from one corner firm case, where replacing the instructions consists of trivial soldering.