Only 308 FPGA LUTs required to create cycle-accurate 8088/8086 soft processor core -

Only 308 FPGA LUTs required to create cycle-accurate 8088/8086 soft processor core

A couple of days ago I heard from an community member called Edward, who is the founder of MicroCore Labs. In his initial message, Edward spake as follows:

Hi Max, I just wanted to let you know that we've released the MCL86 — a micro-sequencer-based, cycle-accurate 8088/8086 soft processor core that consumes only 308 LUTs, which is less than one percent of the smallest Kintex-7 FPGA from Xilinx.

Like the original microprocessor, the MCL86 core's Execution Unit (EU) is independent from the Bus Interface Unit (BIU), thereby providing the user with the freedom to select any type of local bus interface to their FPGA or ASIC design. A cycle-compatible 8088 BIU is provided with the MCL86 core as an example.

Its ultra-small footprint, low power, and cycle compatibility make the MCL86 an ideal choice for an embedded controller that is supported by thousands of applications, tools, and resources dedicated to this extremely well-known instruction set.

Please visit us at to see video demonstrations of the core running popular desktop applications on real hardware.

Edward also included the following photograph of his “Time-Warp” 1985 workstation. As he noted, it wasn't possible to come up with a picture of the “core” that wasn't some boring snapshot of an FPGA with wires sticking out of it, so instead he created a “blast from the past” image that includes some dot-matrix-printed assembly code, a vintage IBM keyboard and monitor, and some large ASCII graphics that are reminiscent of mainframe line printer printouts. The point is that this computer display is being driven by his MCL86 core — pretty nifty, eh?

(Click Here to see a larger image. Source:

Oooh! What can I say? I used to love playing with micro-sequencer-based CPUs although — if the truth be told — the CPUs in question were mainframes and this was way back in the mists of time we used to call the beginning of the 1980s. I actually started to develop a micro-sequencer-based design for a 4-bit CPU as a paper exercise a few years ago, but it made my head hurt, so I stopped.

Of course, I then began to wonder as to Edward's background and why he had created this core in the first place, so I posed these questions to him and he responded in depth…

3 thoughts on “Only 308 FPGA LUTs required to create cycle-accurate 8088/8086 soft processor core

  1. “I could not quite make out if this only uses 308 LUTs or whether it uses 308 LUTS + a whole lot of RAM for the sequencing ROM. If so, it is a bit disingenuous to say “Only 308 FPGA LUTs required…”nnThere is certainly some demand for smallest rather

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  2. “Hi,nnYes, the microsequencer requires 4 of the 135 available block rams of the smallest Kintex device.nnI agree that there are a dizzying array of choices for cores and I suppose that it comes down to what is the best fit for each project and what arc

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