I wonder why I can insert my PC card in reverse or upside down.
The PC card is designed structurally not to be plugged to the connecter upside down or in reverse. Even when the PC card is inserted in reverse or upside down, it is designed not to cause problems such as the crushing of the connecter pins. When you insert the PC card, check carefully its inserting direction and side.
Grooves about 1cm wide are carved on the right and left sides of the PC card. Check the right side of the PC card facing the correct inserting side upward. You will find the groove between 2 protrusions.
On the left side of the PC card, the groove with only one protrusion is carved.
Due to the different design of the grooves between the right side and the left of the PC card, you cannot insert the PC card beyond the length of the groove even when you insert it upside down by mistake. When you insert the PC card in reverse direction, you can only push it in up to the point of 1cm before the connecter, as an ordinary card does not have the grooves.
Some PC card will not have grooves on the edges of the right and left sides sometimes. Check its correct direction and side before inserting it.