FireWire (or at least OHCI-1394) had another fun feature: It exposed memory from the machine over the bus.
https://www.kernel.org/doc/html/latest/core-api/debugging-vi...
[EDIT: This was 100% feature, not bug]
https://www.kernel.org/doc/html/latest/core-api/debugging-vi...
[EDIT: This was 100% feature, not bug]