[BUG] Random hard faults on bootup

[vintagepc]

Describe the bug

Something is not quite right, possibly memory initialization/default values or corruption.

Symptoms:

• There are arbitrary hard faults on bootup that are non-deterministic,
• Arbiitrary "undefined instruction" BSODs.
• Sometimes the sim will reset several times before finally booting.

Figure out why these happen and fix them.

[vintagepc]

I wonder if this was at least partially caused by 74c513d