ARMask.The ARM has six operating modes:

• User (unprivileged mode under which most tasks run)

• FIQ (entered when a high priority (fast) interrupt is raised)

• IRQ (entered when a low priority (normal) interrupt is raised)

• Supervisor (entered on reset and when a Software Interrupt instruction is

executed)

• Abort (used to handle memory access violations)

• Undef (used to handle undefined instructions)

* ARM Architecture Version 4 adds a seventh mode:

• System (privileged mode using the same registers as user mode)