Reverse-engineering the Intel 8086's instruction register (

Ken Shirriff, well known for many notable analysis of dies of famous chips, has done it again. This time it’s about the venerable Intel 8086, which – to all probability – doesn’t require further introduction.

Anyway, here’s Ken Shirriff’s introduction to the topic:

The Intel 8086 microprocessor is one of the most influential chips ever created; it led to the x86 architecture that dominates desktop and server computing today. But it is still simple enough that its circuitry can be studied under the microscope and understood. In this post, I explain the implementation of a dynamic latch, a circuit that holds a single bit. The 8086 has over 80 latches scattered throughout the chip, holding a variety of important processor state bits, but I’ll focus on the eight latches that implement the instruction register and hold the instruction that is being executed.

Mind that this is not the only article by Ken Shirriff on the Intel 8086, see the entire collection here: