
2.1 CPU
39
Common Register Bank Prefix (CMR)
To facilitate exchange of data among multiple tasks, it is necessary to have some relatively simple
means of accessing the same register bank regardless of the value of the RP at the particular moment.
The CMR prefix can be placed before a instruction accessing a general-purpose register, to change all
register access for that instruction to common banks in the range 000180H-00018FH (the register bank
selected when RP=0).
Note that caution is required when using this prefix with the instructions listed in Table 2.1.9.
Table 2.1.9 Instructions Requiring Caution When Used with the Common Register Bank Prefix
Flag Change Suppression Prefix
The flag suppression (or no-change) code (NCC) is used to suppress unwanted flag changes. The NCC
is placed before the instruction in which flag changes are to be suppressed, and will suppress all flag
changes resulting from that instruction. This prefix affects the T, N, Z, V and C flags.
Note that caution is required when using this prefix with the instructions shown in Table 2.1.10.
Table 2.1.10 Instructions Requiring Caution When Used with Flag Change Suppression Prefix
Instruction type
Instruction
Effect of bank select prefix
String instruc-
tions
MOVS
MOVSW
SCEQ
SCWEQ
FILS
FILSW
Do not use the CMR prefix with string
instructions.
Flag change
instructions
AND CCR,#imm8
OR CCR,#imm8
The effect of the prefix will be retained
for the next instruction.
PS recovery
instructions
POPW
PS
The effect of the prefix will be retained
for the next instruction.
ILM setting
instructions
MOV
ILM,#imm8
The effect of the prefix will be retained
for the next instruction.
Instruction type
Instruction
Effect of bank select prefix
String instruc-
tions
MOVS
MOVSW
SCEQ
SCWEQ
FILS
FILSW
Do not use the NCC prefix with string
instructions.
Flag change
instructions
AND CCR,#imm8
OR CCR,#imm8
The CCR will change according to
instruction specifications whether the
prefix is used or not. The effect of the
prefix will be retained for the next
instruction.
PS recovery
instructions
POPW
PS
The CCR will change according to
instruction specifications whether the
prefix is used or not. The effect of the
prefix will be retained for the next
instruction.
ILM setting
instructions
MOV
ILM,#imm8
The effect of the prefix will be retained
for the next instruction.