[edoceo]

ADB and PS/2 didn't look the same. Yes, small circles but IIRC ADB is 4 pins, PS/2 is 6 - and neither could be plugged to the other.

[bshep]

IIRC the rectangular peg in the ADB vs PS2 cable were slightly different and hence incompatible.

[rvense]

And ADB predates PS/2 by about six months, so...