Epson ARM720T Manual Do Utilizador

Table 7-10 shows how to interpret the 

Access Permission

 (AP) bits and how their 

interpretation is dependent on the S and R bits (control register bits 8 and 9).

Table 7-11  Interpreting access permission (AP) bits

b00

0

0

No access

No access 

Any access generates a 
permission fault

b00

1

0

Read-only

No access

Only Supervisor read 
permitted

b00

0

1

Read-only

Read-only

Any write generates a 
permission fault

b00

1

1

Reserved

-

-

a

a.

Do not use this encoding. [S:R] = b11 generates a fault for any access.

b01

x

x

Read/write

No access 

Access allowed only in 
Supervisor mode

b10 x

x

Read/write

Read-only 

Writes in User mode cause 
permission fault

b11 

x

x

Read/write

Read/write 

All access types permitted in 
both modes

bxx

1

1

Reserved

-

-

a