Generally, each driver on your system, including those for network adapters and
SLIP lines, must have its own interrupt
vector (or ``IRQ'').
An interrupt halts processing
momentarily so that input/output or other operations
can occur. Processing resumes after the specific
operation takes place. Consequently, it is important
that each device installed in your
system be provided with an interrupt setting
that does not conflict with the settings used by
the hardware and other peripherals
(unless the device in question supports sharing of interrupts).
Unless a device supports sharing of interrupts,
its interrupt vector must not be used by any other device on the system.
Refer to your networking hardware documentation
to determine which vectors the hardware supports.
The
DCU
(Device Configuration Utility)
lists the hardware already installed on your system and
what vectors are already in use.
NOTE:
Some devices must be configured using SCOadmin managers; see
``Using configuration interfaces''.
In particular, you must use the Network Configuration
Manager to configure network adapters.
Standard hardware interrupt vectors (IRQs)
IRQ
Description (driver)
Notes
0
~
Reserved
1
Keyboard driver (kd)
Reserved
2
~
Available (IRQ 2 is internally mapped to
IRQ 9. When choosing IRQ values, you should
consider IRQ 2 and IRQ 9 to be the same
interrupt.)
3
Serial COM2 port (asyc)
Reserved if present (unless disabled in the BIOS or
with the
DCU)
4
Serial COM1 port (asyc)
Reserved if present (unless disabled in the BIOS or
with the
DCU)
5
Cartridge tape (ictha) or parallel port #2 (lp)
Recommended cartridge tape setting if installing from
non-SCSI cartridge tape drive and a printer is not
assigned to this IRQ
6
Floppy disk (fd)
Reserved
7
Parallel port #1 (lp)
Required if present and used at that setting
(unless disabled in the BIOS or with the
DCU)
8
Real-time clock (rtc)
Reserved
9
~
Available
10
~
Available
11
~
Available
12
PS/2 mouse
Reserved if PS/2 mouse us installed
13
Math coprocessor and programmable interrupt controller (atup)
Reserved
14
Integral hard disk (dcd/athd)
Only required if an IDE, ESDI, or
ST506 hard disk is installed
15
~
Available
To install a networking adapter and driver software,
you must choose an interrupt vector
(IRQ) setting for the adapter.
Consult the adapter's documentation for
acceptable IRQ settings.
After you determine your hardware's IRQ settings,
choose settings for each networking adapter that you plan to install,
making sure that the settings do not conflict with each other.
The documentation for each networking adapter should indicate
whether you need to configure the adapter physically to
use the chosen IRQ setting.
The operating system reserves interrupt vectors 4 and 7 for
COM1 and lpt0, respectively.
If you choose any setting that is either a setting
reserved for another use or is in use by another
device, a conflict occurs.
Some SCOadmin managers may be able to detect conflicts.
If yours is an ISA system, your networking
hardware might be preconfigured to use a particular vector.
If you want to change this vector setting, you might also need to
change the physical jumper settings on the adapter or run a setup
program provided with the adapter.
NOTE:
A number of networking adapters are preconfigured to use interrupt
vector 3; the BIOS might also choose to use interrupt
vector 3 on PCI or EISA buses. Your operating
system has reserved IRQ3 for the
asyc(7)
serial I/O device.
However, some BIOS setup programs permit IRQ
reassignment; see your hardware documentation for more information.