[TUHS] Early non-Unix filesystems?

[Ron Natalie]

> Ok. Color me stupid, but I don't get it. I totally do not understand how this locks anything out.

I misstated that a bit.   The issue is if the next instruction is also an SPL instruction, then interrupts never get enabled.    So if you have a run of SPL instructions, interrupts are locked out for the duration.    If you can fill your address space with SPL instructions (provided the OS doesn't fail in the process), you can cause an uninterruptable loop.   Interupt includes the HALT switch on the front.   You have to use the BUS RESET to jab it out of its catatonic state.