UPD784938 Datasheet, PDF (525/733 Pages) NEC – 16-Bit Single-Chip Microcontrollers

CHAPTER 23 INTERRUPT FUNCTIONS
The µPD784938 is provided with three interrupt request service modes (see Table 23-1). These three service modes
can be set as required in the program. However interrupt service by macro service can only be selected for interrupt request
sources provided with the macro service processing mode shown in Table 23-2. Context switching cannot be selected for
non-maskable interrupts or operand error interrupts.
Multiple-interrupt control using 4 priority levels can easily be performed for maskable vectored interrupts.
Table 23-1. Interrupt Request Service Modes
Interrupt Request
Service Mode
Vectored interrupts
Context switching
Macro service
Servicing Performed
PC & PSW Contents
Service
Software
Hardware
(firmware)
Saving to & restoration
from stack
Saving to & restoration
from fixed area in
register bank
Retained
Executed by branching to service program at
address^Note specified by vector table
Executed by automatic switching to register
bank specified by vector table and branching
to service program at address^Note specified by
fixed area in register bank
Execution of pre-set service such as data
transfers between memory and I/O
Note The start addresses of all interrupt service programs must be in the base area. If the body of a service program
cannot be located in the base area, a branch instruction to the service program should be written in the base area.
Preliminary User’s Manual U13987EJ1V0UM00
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