Imagesource: https://unsplash.com/

This week the Microcode Decryptor for x86 CPUs surfaced. But for historical and other reasons, we'd better not go into it. 👹

However, anyone who tried to come up with their own CPU architecture will be familiar with microcode and its challenges. Do you decode instructions directly using circuits on hardware level like in early CPUs like the Z80 or the MOS8502? Or do you choose a ROM based approach like in the SAP architecture? Or do you take a completely different path in order to transplant the own instruction set into the hardware?

In the end microcode controls exactly those devices of a CPU, which for a certain operation either put something on address, data or ALU buses, or read from them in every single clock cycle.

Mark Smotherman can be called an expert in this field. And if you feel like expanding your knowledge, you should read Mark's excellent essay on the subject.

Recommended read. 📓