A few past related threads:
J2 open processor: an open source processor using the SuperH ISA - https://news.ycombinator.com/item?id=26866065 - April 2021 (45 comments)
The SuperH-3, part 15: Code walkthrough - https://news.ycombinator.com/item?id=20779622 - Aug 2019 (1 comment)
The SuperH-3, part 1: Introduction - https://news.ycombinator.com/item?id=20622921 - Aug 2019 (2 comments)
Building a SuperH-compatible CPU from scratch [video] - https://news.ycombinator.com/item?id=11886079 - June 2016 (24 comments)
Resurrecting the SuperH architecture - https://news.ycombinator.com/item?id=9812010 - July 2015 (15 comments)