4. Interrupt Controller
ÛZIATECH
38
Notes:
1. CTC1-Ch0: System Timer.
2. The default IRQ1 source depends on the status of jumper W5: when W5 is removed,
IRQ1 = Local Keyboard; when W5 is installed, IRQ1 = INTRQ1
*
. IRQ1 is normally
used for the keyboard interrupt. If your system has a backplane video card with a
keyboard controller (such as the ZT 8982), install jumper W5 to disable the on-board
keyboard controller. W5 must be removed when using local video or no-video.
3. Also supports INTRQ
*
, INTRQ1
*
INTRQ2
*
, INTRQ3
*
, INTRQ4
*
, and J1--pins 2, 4, 6,
8, 10.
4. Second interrupt controller (8259).
5. Real Time Clock interrupt.
6. Math coprocessor exception interrupt.
7. Enable the ZT 8907 for either local IDE or STD 32 IDE operation through the BIOS
SETUP utility. See "
" in Chapter 17 for details.
8. The default IRQ15 source depends on the status of cuttable traces CT7 and CT8
(see Appendix A, "
"). Other interrupt sources are possible for
IRQ15 with custom software configuration. Contact Ziatech for details.
INTERRUPT SOURCES
The interrupt sources are summarized below.
Backplane:
There are five STD bus interrupts routed to the interrupt configuration
logic, configurable through the BIOS SETUP utility, screen 2. These
interrupts are labeled INTRQ*, INTRQ1*, INTRQ2*, INTRQ3*, and
INTRQ4*. All five interrupts are supported in an STD 32 backplane and all
but INTRQ3* are supported in an STD-80 backplane. These interrupts are
active-low on the STD bus and inverted before they reach the interrupt
configuration logic.
Frontplane:
There are five frontplane interrupts routed to the interrupt configuration
logic. These interrupts are available through connector J1 as active-low
inputs that are inverted before reaching the interrupt configuration logic.
The pin assignments for connector J1 are given in the "
" topic
in Appendix B, "Specifications." Many STD bus boards include a J1-
compatible connector for routing interrupts to the ZT 8907 through a
ribbon cable. This architecture is useful if the application requires more
interrupts than are available on the STD bus.
PCI:
Three interrupt levels may be assigned to the PCI bus when not used for
other devices. IR10, IR11, and IR12 may be allocated to PCI through