4 Knights

(this puzzle was taken from an old adventure game)

Prenises:
You are playing on a 4x4 chessboard.
So, columns are a, b, c, d.
Ranks are 1, 2 , 3, 4.
There are in the initial position 2 white Knights on b1, c1, and
2 black knights on b4, c4.
You must interchange the Knights positions (that is, the final position should be
2 white Knights at b4, c4, and 2 black Knights at b1. c1).

Condition:
During the moves, no piece can be subject to being captured.

White to move.

And a honest advice: This can't be solved in less than 64 moves!
But don't be afraid! Try to solve it!

I got it in 8 moves (16 jumps):

1. Nb3 Nb2
2. Nc3 Nc2
3. Nd2 Nd3
4. Nc4 Nc1
5. Nb1 Nb4
6. Nba3 Nba2
7. Nc2 Nc3
8. Nb4 Nb1

Originally posted by PBE6
I got it in 8 moves (16 jumps):

1. Nb3 Nb2
2. Nc3 Nc2
3. Nd2 Nd3
4. Nc4 Nc1
5. Nb1 Nb4
6. Nba3 Nba2
7. Nc2 Nc3
8. Nb4 Nb1

It's also insanely obvious.....

Originally posted by LittleBear
Fine! My congrats, PBE6!
Clean solution.

My apologies for my posting, 'cos my memory failed miserably 😳

The puzzle I intended to post was very similar.
The corrections:

Board size: 5x5.
Columns: a, b, c, d, e.
Raws: 1 to 5.

Initial position of the white knights: b1, d1.
Initial position of the black knights: b5. d5.

Same objective.

P.S.: I'm going to rec your solution, PBE6. It is clean, methodic, short and elegant!

Originally posted by LittleBear
Fine! My congrats, PBE6!
Clean solution.

My apologies for my posting, 'cos my memory failed miserably 😳

The puzzle I intended to post was very similar.
The corrections:

Board size: 5x5.
Columns: a, b, c, d, e.
Raws: 1 to 5.

Initial position of the white knights: b1, d1.
Initial position of the black knights: b5. d5.

Same objective.

P.S.: I'm going to rec your solution, PBE6. It is clean, methodic, short and elegant!