Demystifying IDE modes and jumpers

IDE devices have 2 or 3 active modes and one ‚don’t care‘ mode. A controller channel in most computers supports up to 2 devices, one jumpered as active master and one jumpered as active slave. Just to confuse matters, most IDE devices carry a jumper or even two jumpers that may be doing nothing, just sitting in a ’single‘ or ‚don’t care‘ mode. This can be the situation with consumer computers built after 1996, where each of two IDE devices can just be plugged into each of the two IDE channels built into the motherboard. A special mode called Cable Select is provided on hard drives – but used only with special IDE cables in RAID systems.
When you are faced with changing IDE devices around to install and run BeOS, the best – and only – plan is to first contact the manufacturer of the computer system or the manufacturer of each device for correct jumper information. Historically, hard drive jumper positions have changed between models from the same firm AND between units of the same model. You should write down complete model and serial numbers to completely identify the device. These are usually on a label on the top of each unit, so removing the devices from their mounting slots is necessary.
Before you undertake this chore, turn on your system and look at the messages on the screen. The first group of messages will include one on using a function key to launch the Setup program built into your bios. Do this. Setup will show, on its first page, the current status of your IDE devices AND their logical locations on the IDE channel(s). You may not have to change anything.
As BeOS matures, its ability to handle IDE devices will undoubtedly become as flexible as the handling provided in Windows95, so moving jumpers around should become a nice tale to tell future generations.



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