
2.1 CPU
32
Chapter 2: Hardware
Table 2.1.8 Instructions Retaining Bank Select Prefix Effect Until Next Instruction
s Continuous Bank Select Prefix Codes
If bank select prefix codes are continuous, the last code is effective.
Fig. 2.1.19 Continuous Prefix Codes
s 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 regardless of the value of the RP at the particular moment. The
CMR prefix can be placed before an instruction accessing a general-purpose register, to change all
register accesses for that instruction to common banks in the range 000180H to 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 in Using the Common Register Bank Prefix
Instruction type
Instruction
Flag change instructions
AND
CCR,#imm8
OR
CCR,#imm8
PS recovery instructions
POPW
PS
ILM set instructions
MOV
ILM,#imm8
Instruction type
Instruction
Function
String instructions
MOVS
MOVSW
SCEQ
SCWEQ
FILS
FILSW
Do not use the CMR prefix with
string instructions.
Flag change instruc-
tions
AND
CCR,#imm8
OR
CCR,#imm8
The effect of the prefix is retained
for the next instruction.
PS recovery instruc-
tions
POPW
PS
The effect of the prefix is retained
for the next instruction.
ILM setting instruc-
tions
MOV
ILM,#imm8
The effect of the prefix is retained
for the next instruction.
Prefix codes
↑ The PCB prefix code will become effective.
……
ADB
ADD A, 01H
DTB
PCB