8086 Microcode Browser
8 days ago
- #CPU
- #microcode
- #8086
- The author has been working on recreating the 8086 with a design faithful to the original, leading to exploration of its microcode.
- An interactive browser for the 8086 microcode ROM has been created, decoding every 21-bit micro-instruction into readable fields with tooltips.
- Features include browsing by instruction, with a list of ~300 documented 8086 instructions, linking directly to their μcode entry points.
- Interesting insights about 8086 microcode include context-dependent register IDs, shared arithmetic instruction micro-operations, and IP behavior.
- The microcode reveals the 8086's evolutionary design process, with inconsistent naming and elegant reuse of micro-operations.