Using Primary Drives; Using Secondary Drives; Using 3.5" Ide Devices - Allen-Bradley 1747-OC Series User Manual

5-8 Defining System Settings
1747-UM001A-US-P - March 2000

Using primary drives

If you have a: Then:
• The primary master and primary slave drives share IRQ 14. Leave
1747-OCE
this interrupt defined as PCI/PnP.
• No open controller option module is ever assigned this interrupt.
• IRQ 14 is dedicated to the primary IDE channel and is not
1747-OCF
configurable.
Important: Some operating systems, such as Windows NT, only boot from
a primary master drive.

Using secondary drives

The secondary master and secondary slave drives share IRQ 15.
If you have a: Then:
• Leave this interrupt defined as ISA/EISA if you are using an ATA
1747-OCE
drive in a PCMCIA interface module.
• Change this interrupt to PCI/PnP if you are using an IDE interface
module.
• No open controller option module is ever assigned this interrupt.
• Always configure IRQ15 for ISA if you are using an ATA drive in a
1747-OCF
PCMCIA interface module or an IDE interface module. Otherwise,
this interrupt works just like all others and can be assigned to open
controller option modules.

Using 3.5" IDE devices

When you connect devices to the 3.5" connector on the IDE interface
module, you select master/slave by jumpers on the external device. You
select primary/secondary by which connector you connect to on the IDE
interface module.
If you only have one IDE interface module with an external CD-ROM
device, you will get better performance if you configure the internal IDE
drive as a primary master and the external CD-ROM as a secondary master,
rather than have both share the same primary or secondary channel.