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external display as primary output device?
Authored by: sjk on Mar 27, '06 06:38:07PM

Anyone here know if it's possible to configure an external monitor as the primary output device for system startup? If possible, the idea is to bypass the internal display if it ever fails for some reason. For example, you could "blind boot" the system into single-user mode, run a script to select the external monitor as the output device, and future reboots would use the external monitor instead of the internal display. This would allow use of the system without repairing the internal display, which is something I'd really like to do if/when the CRT on my wife's eMac eventually dies.



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external display as primary output device?
Authored by: Dragon76 on Mar 28, '06 10:02:55AM

There used to be a key combination for old Macs that you could use to start from an external display, but all I can find on google are the ones for Quadra AV machines to force using a TV as a monitor (cmd-opt-t-v) and to force an AV monitor to be recognised as one (cmd-opt-a-v). Maybe one of those might work.



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Easy
Authored by: VRic on Mar 30, '06 10:22:48AM
Anyone here know if it's possible to configure an external monitor as the primary output device for system startup?

First, what's wrong with the standard feature, which has been there for decades? Prefpane Monitors:Arrange: in the miniature representation of available monitors, drag the menu bar from one to another.

If you want to do it AFTER your main monitor dies, you can have SwitchRes installed and configured beforehand to present you with any number of choices or presets by right-clicking on the desktop (on the monitor that works).
SwitchRes screenshots

You can also assign a hotkey to open the Monitors prefpane or a script that opens it and drags it to the secondary monitor so that you won't have to grab it blindly.

If you're OK with the command line, you can also install cscreen and memorize its commands (since you wouldn't see the display if it's dead).
cscreen on macosxhints

Monitor settings being saved in PRAM and in a prefs file somewhere, you could also research ways to set it at boot time using Open Firmware, or switch between 2 preset prefs files using single user mode and reboot, or set the pref using the "defaults" command and reboot. But managing any of that without seing the CLI output would be needlessly hard.

What makes you so sure the built-in monitor will die anyway?



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Maybe I misinterpreted
Authored by: VRic on Mar 30, '06 10:37:49AM

Having re-read your question, it seems you want a way to route the display to a secondary monitor IF and AFTER the built-in one dies, but without having it connected by default in normal use.

The suggestions I made above work for that of course, but you could also:

- connect the monitor you would be using (preferably that one, as the system is likely to recognize it and may not treat another one the same)

- use the Monitors prefpane to set it as the main monitor

- shut down, disconnect the secondary monitor until needed

On subsequent reboots, the secondary monitor will be main if present, if not the OS will revert to the built-in one. The setting should remain until you make another change to the monitors prefs or zap the PRAM.



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Maybe I misinterpreted
Authored by: sjk on Mar 30, '06 08:03:22PM

I'll try temporarily making an external monitor the primary display, then detaching it and seeing if the internal monitor is used automatically. If that doesn't work I'll investigate your other suggestions (thanks!).

For starters, maybe it's enough to set output-device to screen1 (or other value) in Open Firmware; I'll check that OF variable and other things after making the external monitor primary. That mode wouldn't initially have to have optimal settings, just enough to see things and make adjustments afterwards. Hmm, just noticed "output-device-1 scca" in OF; I'll search for info about that.

I've never used a second monitor on my Macs or I'd probably already know more about this stuff by now.

I'm more than "OK" with the command line.

I'm not thinking the internal monitor will die, just wanting to be prepared with a less expensive option than getting it repaired or buying a new system. I want a safety net for hardware failures whenever possible.



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