24 Mar
2016
24 Mar
'16
12:35 p.m.
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.