If it’s physically impossible to write to a ROM (read-only memory) cartridge, how do manufacturers do it?

Question

Is somehow locked physically during production, or through software?

In: 210

Answer 1

In ancient times, writing was done on soft clay. When done and to preseve it, the clay is heated until it hardens. That’s your ROM. It was totally possible to write to it initially, but now you cannot simply delete, add or change content. All you could do is destroy it and make a new one.