The MCL86jr is a 8088 drop-in replacement for the IBM PCjr which expands the system's memory to the full 640 KB and can run either cycle acurate or acelerated.
It uses the MCL86 EU core combined with a minimim-mode BIU and access to a 512KB Static RAM to bring the PCjr to the full 640 KB of RAM.
While the MCL86jr can run cycle accurate, it can also run in an accelerated mode where it achieves a speed improvement of around 4X which is about as fast as an IBM PC-AT!