Hackaday

The Intel 8086 CPU uses a unique ALU design with microcode and lookup tables to configure operations, unlike the 6502's separate circuits or 8085's reconfigurable gates. This CISC-style approach allows one microcode to serve multiple instructions, creating flexibility at the cost of complexity. The lookup table-based reconfiguration is conceptually similar to modern FPGA technology, and while these trade-offs mattered in the 1970s, improved semiconductor and design technologies have reduced their relevance over time.

The Inner Workings Of The Intel 8086’s Arithmetic Logic Unit