MOTOROLA
Chapter 22. CALRAM Operation
22-15
Programming Model
21
D0
Data-only/data-instruction privilege (Data type assignment) — If the data relocate (DR) bit is set
in Machine Status Register (MSR) and D0 is also set, then any access attempting to fetch an
instruction from the array block generates an error. If DR bit is 0, both data read and instruction
fetch from the array block is allowed, regardless of the value programmed in D0.
This bit controls the highest 8-Kbyte block (lowest address) of CALRAM in the associated array.
Likewise, D1, D2, and D3 control three other 8-Kbyte blocks in the same manner. See
Table 22-4for control bit address ranges.
D0 = 0 and DR = 0 data and/or Instruction (array 8-Kbyte block)
D0 = 0 and DR = 1 data and/or Instruction (array 8-Kbyte block)
D0 = 1 and DR = 0 data and/or Instruction (array 8-Kbyte block)
D0 = 1 and DR = 1 data only (array 8-Kbyte block)
22
S0
Supervisor-only/supervisor-user privilege (Space assignment) — If the data relocate (DR) bit is
set in Machine Status Register (MSR) and S0 is also set, then any access to the array block by
a user program generates an error. If DR bit is 0, both user and supervisor program can access
the array block, regardless of the value programmed in S0. The CALRAM array may be placed
in supervisor or unrestricted space.
This bit controls the highest 8-Kbyte block (lowest address) of CALRAM in the associated array.
Likewise, S1, S2, and S3 control other three blocks in the same manner. See
Table 22-4 for
control bit address ranges.
S0 = 0 and DR = 0 both user and supervisor access allowed (array 8-Kbyte block)
S0 = 0 and DR = 1 both user and supervisor access allowed (array 8-Kbyte block)
S0 = 1 and DR = 0 both user and supervisor access allowed (array 8-Kbyte block)
S0 = 1 and DR = 1 only supervisor access allowed (array 8-Kbyte block)
23
R1
Same as R0 except for address ranges shown on
Table 22-4.
24
D1
Same as D0 except for address ranges shown on
Table 22-4.
25
S1
Same as S0 except for address ranges shown on
Table 22-4.26
R2
Same as R0 except for address ranges shown on
Table 22-4.
27
D2
Same as D0 except for address ranges shown on
Table 22-4.
28
S2
Same as S0 except for address ranges shown on
Table 22-4.29
R3
Same as R0 except for address ranges shown on
Table 22-4.
30
D3
Same as D0 except for address ranges shown on
Table 22-4.
31
S3
Same as S0 except for address ranges shown on
Table 22-4.Table 22-4. CRAMMCR Privilege Bit Assignment for 8-Kbyte Array Blocks
Bit Selection
Address Block (Relative)
R0, D0, and S0
0xXXXX 0000 – 0xXXXX 1FFF
R1, D1, and S1
0xXXXX 2000 – 0xXXXX 3FFF
R2, D2, and S2
0xXXXX 4000 – 0xXXXX 5FFF
R3, D3, and S3
0xXXXX 6000 – 0xXXXX 7FFF
Table 22-3. CRAMMCR Bit Descriptions (continued)
Bits
Name
Description