Restrictions On Prefix Code; Fig. 2.28 Interrupt/Hold Inhibition; Table 2-12 Prefix Code And Interrupt/Hold Inhibit Instruction - Fujitsu MB90420/5 (A) Series Hardware Manual

MB90420/5 (A) SERIES F

2.9.4 Restrictions on Prefix Code

The prefix code has the following three restrictions.
• The interrupt/hold request is not accepted during the prefix code or the interrupt/hold inhibit instruction.
• When the interrupt/hold instruction is prefixed by the prefix code, the effect of the prefix code is delayed.
• When some conflicting prefix codes are successive, the last one is effective.
n Prefix code and Interrupt/hold inhibit instruction
As shown in the Table 2-12, interrupt/hold inhibit instruction and prefix code are restricted.

Table 2-12 Prefix Code and Interrupt/hold Inhibit Instruction

Instruction that does not
accept interrupt request or
hold request
• Interrupt/hold inhibition
As shown in Figure 2.28, the interrupt request or the hold request is not accepted during execution of the
prefix code or the interrupt/hold inhibit instruction. In this case, the interrupt/hold handling is performed
after the first instruction other than the prefix code or the interrupt/hold inhibit instruction is executed
following the prefix code or the interrupt/hold inhibit instruction.
Issuance of interrupt request
2
MC-16LX FAMILY 16-BIT MICROCONTROLLERS HARDWARE MANUAL
Prefix
Code
PCB MOV
DTB OR
ADB AND
SPB POPW
CMR
NCC
Interrupt/hold inhibit instruction
• • • • • • • • • • • • • • •

Fig. 2.28 Interrupt/hold Inhibition

Interrupt/Hold Inhibit Instruction
(instruction that delays effect of prefix code)
LM, #imm8
CCR, #imm8
CCR, #imm8
PS
2-34
• • •
(a)
(a) Ordinary
instruction
Acceptance of interrupt