The N64 has a software lockout, but this only applies to NTSC/PAL unlike region lockouts today. The reason PAL carts will not work in an NTSC unit is due to the PIF-NUS chip (Peripheral Interface) being different. So if you hypothetically switched these chips (NTSC PIF-NUS in a PAL unit and PAL PIF-NUS in an NTSC unit), they would switch regions. Now, in the case of playing Japanese imports in an American unit, it's as simple as removing the tabs previously mentioned. This is because the American and Japanese consoles share the same PIF-NUS chip, and the only lockout they have is mechanical. Now, as also previously mentioned, there are some passthrough cartridges that allow you to play NTSC games in a PAL unit without the swapping of the PIF-NUS chips, though I am not very familiar with these and could not give suitable advice. Judging from the picture the OP posted, he has a PAL console and would not be able to region free his console by removing the tabs.