For questions about copy protection techniques used on retro software.

Two aspects of copy protection are relevant to retro-computing:

  1. Preservation of old software. Physical media decays, so getting a working copy of the software often requires defeating copy protection.
  2. Insight into hardware. Copy protection often takes advantage of edge cases and obscure knowledge, e.g. deliberately using a broken 6502 instruction to confuse people tracing through code. Exploring specific examples can be very educational.

These actions should not be used to violate copyright law.

In the United States, the DMCA initially prevented research into copy protection techniques, but was later amended to allow research and circumvention for "abandonware" (cf. wikipedia).