RTE-V831-PC
USER’S MANUAL (Rev. 2.00)
22
9.
INTERRUPTS AND DMA
This chapter describes the interrupts and DMA for the RTE-V831-PC.
9.1.
INTERRUPT
External interrupts are used as indicated below.
Interrupt
Source
NMI
Interrupt from the ROM emulator, and INT0 interrupt by PIC setting (for the monitor)
INTP03
INT0 interrupt by PIC setting (for the monitor)
INTP02
INT1 interrupt by PIC setting (for the user)
INTP01
Interrupt from the EXT (extension) bus
INTP00
Interrupt from the audio interface (when an error occurs)
INTP13
Not used
INTP12
Not used
INTP11
Not used
INTP10
Not used
Two interrupts (INT0, INT1) can be generated by selecting interrupt requests from the interrupt sources
listed below with the interrupt controller (see Section 8.9.) on the board. INT0 is used for the system
(used with the Multi monitor), while INT1 is used for a user application.
Interrupt source
Timer 0 (mode 2)
Serial 0
Host (ISA communication)
Time-over
Timer 1 (mode 2)
Serial 1
Parallel (printer)
ISA-IRQ
9.2.
USING NMI
This section describes the method of using NMI for transporting the monitor, for example, to the board.
NMI is edge-detected. NMI can be masked by hardware because the interrupt source is a level output.
For an explanation of masking, see the description of the INTEN register in Section 8.9.
The following procedure applies when an NMI occurs.
<1>
Set the NMIEN of the PIC to 0 to mask the NMI by hardware.
<2>
Check the INTR of the PIC.
<3>
Perform NMI processing for the interrupt source, and clear the request.
<4>
Reset the NMIEN of the PIC to 1 to reset the mask.
<5>
Return from NMI processing.
[Caution]
When the monitor is used, the operation of an INT0-related register of PIC, NMI, or INTP03
may cause the monitor to hang.
