3.7.11. The M bits

M[4:0] are the mode bits. These bits determine the processor operating mode as Table 3.3 shows.

Table 3.3. PSR ode bit values

M[4:0]

Mode

b10000

User

b10001

FIQ

b10010

IRQ

b10011

Supervisor

b10111

Abort

b11011

Undefined

b11111

System


Note

  • In Privileged mode an illegal value programmed into M[4:0] causes the processor to enter System mode.

  • In User mode M[4:0] can be read. Writes to M[4:0] are ignored.

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