How flip-flops are implemented in the Intel 8086 processor

A circuit called the flip-flop is a fundamental building block for sequential logic. A flip-flop can hold one bit of state, a “0” or a “1”, changing its value when the clock changes. Flip-flops are a key part of processors, with multiple roles. Several flip-flops can be combined to form a register, holding a value. Flip-flops are also used to build “state machines”, circuits that move from step to step in a controlled sequence. A flip-flops can also delay a signal, holding it from from one clock cycle to the next.

Intel introduced the groundbreaking 8086 microprocessor in 1978, starting the x86 architecture that is widely used today. In this blog post, I take a close look at the flip-flops in the 8086: what they do and how they are implemented. In particular, I will focus on the dynamic flip-flop, which holds its value using capacitance, much like DRAM. Many of these flip-flops use a somewhat unusual “enable” input, which allows the flip-flop to hold its value for multiple clock cycles.

More in-depth chip content. This type of content has been coming up a lot lately.

One Response

  1. 2023-10-01 2:35 pm