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Q:  What is the Force Dev 1 Present Setting on the IBM 75GXP IDE drive for?

A:  My guide to adding a 2nd drive in a G4 at the main www.xlr8yourmac.com IDE articles page used an IBM 75GXP as the slave drive to a Maxtor master drive. For that configuration the 75GXP needs only to be set to Slave as shown in the picture of the jumper settings for the drive in that article. (If you're using a Western Digital or Quantum drive as the master drive - check the jumper settings - you may have to change them to "master" if the drive is set to a 'single drive' setting. See the links below for pages with IBM, WD and Quantum drive jumper settings info.)

There is a setting on the 75GXP that I noted in the forums here some time back that should only be needed if your slave drive is a very old model IDE drive - it's the "Dev 0 Force Dev1 Present" setting (i.e. force recognition of the slave drive for drives that do not make their presence known on the bus).

Here's a quote right from IBM's 75GXP manual (page 48).

" Slave Present (Device 0 forcing Device 1 Present)
If your Slave drive is an older drive that may not signal its presence on the bus,
set the jumpers on your Master drive to Slave Present"

What that's sayings is the "Dev 0 Force Dev 1 Present" setting is a workaround to have the master drive let the system know there's a slave drive on the bus for cases where the slave drive is an older model that does not properly signal its presence on the IDE bus. The above quote is right out of the IBM 75GXP manual, so with modern IDE drives, you should not have to use this setting.
For older IDE drives used as a slave however, you may have to for the slave drive to be detected.

There could be some quirk in some older Mac IDE interfaces where this setting may be of help even with a modern slave drive, but it should not be needed otherwise (if the slave drive is detected). One reader wrote to say he saw a claim where the "force Dev1 present" setting doubled master to slave drive copy performance, but with modern drives and interfaces I'd doubt that claim, but will test it as soon as I can.

With some drives I mentioned in past guides and here inthe FAQ (i.e. many Western Digital drives and some Quantums) that have "single drive" and "master" settings, normally the slave drive will not appear if the settings on the master (first) drive is not changed from "single drive" to "master" setting. (Master means "master with slave present" on those drives.) If you add a slave drive jumpered properly and it does not mount, check the master drive settings to see if it is set to a "single drive" setting. (Or if a 75GXP - try the force Dev1 setting).

Links to Drive Jumper Settings Info:

• IBM IDE Drive Jumper Settings Page
  (BTW - The above page shows "Device 0 present" wording instead of what's on the drive settings label and in the manual for the 75GXP drive which calls that setting "Dev 0 Forcing Dev 1 Present")
• Quantum Fireball Plus AS Jumper settings page
• Western Digital Jumper Settings page