PCXT Hardware - Maverick-Shark/retroGuru GitHub Wiki
IBM 5160 Switch/Jumper Settings
https://www.minuszerodegrees.net/5160/misc/5160_motherboard_switch_settings.htm
IBM PC and XT DIP Switch Settings
https://dosdays.co.uk/topics/xt_dip_switches.php
8255 PPI (Programmable Peripheral Interface)
https://github.com/jotego/jt8255/blob/master/hdl/jt8255.v
https://github.com/EL-SHREIF/PPI-Project-
https://github.com/zyad19975/PPI-Intel-8255A