Why Raspberry Pi isn't vulnerable to Spectre or Meltdown - Raspberry Pi

Eben Upton provides a wonderfully clear explanation of recently-disclosed CPU vulnerabilities: Why Raspberry Pi isn't vulnerable to Spectre or Meltdown - Raspberry Pi. I think this is the clearest writing on CPU architecture details that I've seen, aside from articles in BYTE magazine in the early 1980s. The comment thread is also a fun read, not least for its mention of the Motorola 68000.