Interrupt Functions - NEC PC-8201 Service Manual

3.1.1 1
lnterrupt Functions
The PC-8201 is equipped with a 4-priority level interrupt control logic. The interrupts are
input to the 80C85 (TRAP, RST 7.5. 6.5, 5.5). TRAP is nonmaskable; rlie others can be
masked by software control.
POWER TRAP
KEY INT
Function
POWER
TRAP
K E Y
I N T
U A R T
BCR
Priority
High
Low
Power voltage is low. If it becomes less than
a certain value. the interrupt is enabled and
power automatically turns off.
Interrupt Channel
TRAP
RST 7.5
RST 6.5
RST 5.5
Searches the input key by the 256 kHz clock
which is transmitted from the timer chip.
pPD
1990AC.
UART Received interrupt from UART IM6402
BCR Interrupt from bar code reader
All interrupts except TRAP have an exclusive use mask flag, so each can be individually
masked.
The mask flag is set or reset by the SIhl (Set Interrupt h4ask) command.
See the command of 80C85.
4 3 2
1
0
ACC
R7.5 MSE M7.5 M6.5 M5.5