https://psx0.wordpress.com/2013/01/22/psone-usb-link-serial http://mgarcia.org/Blog/2019-08-24-PSONE-Serial https://web.archive.org/web/20191108145318/https://assemblergames.com/threads/add-a-link-port-to-the-psone.19777/page-2 http://www.psxdev.net/forum/viewtopic.php?t=1071