It also appears that I may not have been the first one to discover that something odd was going on with that bit, causing it to use A0-A7 (with weird results) i

It also appears that I may not have been the first one to discover that something odd was going on with that bit, causing it to use A0-A7 (with weird results) instead of D0-D7: https://eab.abime.net/showthread.php?t=119675 https://eab.abime.net/showthread.php?t=119675