The MCL86 is an open source, cycle accurate, microsequencer-based FPGA core which can be used as as an embedded processor or as a drop-in replacement for the Intel 8088 or 8086.
It has successfully been used in IBM PC, XT, and PCjr computers as well as the MiSTer PCXT project.
The MCL86 is a 16-bit, microsequencer based, cycle acurate and structurally compatible soft IP core for the Intel 8086/8088 microprocessor. Like the original CPU, the MCL86 Execution Unit (EU) is separate from the Bus Interface Unit (BIU) which allows it to be utilized in a wide range of applications from a drop-in 8086/8086 replacement to a highly customized system-on-a-chip. The MCL86 consumes a minimal amount of space and power which leaves the majority of the silicon available for other logic.
The MCL86 EU core utilizes only 308 Xilinx LUTs which is less than one percent of the smallest Kintex FPGA and less than ten percent of the Lattice XO2-7000 FPGA. It has also been ported to Intel/Altera FPGAs.
The MCL86 core has been extensively tested in simulation, against an opcode test suite, as a drop-in replacement for multiple vintage computers, and running hundreds of games via MiSTer PCXT. I have uploaded a number of videos to YouTube videos of the MCL86 running applications which include the technically strenuous 8088 MPH demo.
The core has the option to be cycle compatible with the original 4.77Mhz 8088 microprocessor which allows the MCL86 to be a drop-in replacement or it can be allowed to execute instructions around 400% faster.
It was selected as the CPU core for the MiSTer PCXT project where the goal was to have a cycle-accurate emulation of the IBM and Tandy 8088-based computers.
One fun application of the core was the MCL86jr where the MCL86 was paired with a minimum-mode BIU and 512KB of SRAM to produce the "World's Fastest PCjr" which increased the PCjr's speed by 6X!
It is also, to my knowledge, the only open-source, cycle accurate 8086 core available.