National Instruments PC-DIO-96 - page 46

Register-Level Programming Chapter 4
PC-DIO-96 User Manual 4-8 © National Instruments Corporation
Interrupt Control Register 2
D7 D6 D5 D4 D3 D2 D1 D0
XXXXXINTEN CTRIRQ CTR1
Bit Name Description
7–3 X Don’t Care Bit.
2INTEN Global Interrupt Enable Bit—If this bit is set, the PC-DIO-96 can
interrupt the host computer. If this bit is cleared, the PC-DIO-96
interrupt line is put into high-impedance mode, so other devices
can use the interrupt channel selected by jumper W1.
1CTRIRQ Counter Interrupt Enable Bit—If this bit is set, the 8253 counter
outputs can interrupt the host computer. If this bit is cleared, the
counter outputs have no effect.
0 CTR1 Counter 1 Enable Bit—If this bit is set, the output from counter 1
of the 8253 is connected to the interrupt request circuitry. In this
mode, counter 0 of the 8253 acts as a frequency scaler for
counter 1, which generates the interrupt. If CTR1 is cleared, the
output from counter 0 of the 8253 is connected to the interrupt
request circuitry. In this mode, counter 0 generates the interrupt.
For more information, see the section later in this chapter on
programming interrupts using the 8253.