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Last revised: Oct. 22, 2002

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Extended Desktop on Apple's i-Line

I'm currently in the process of redesigning this web page. Please don't mind the nonexistant layout for now ;)

Important Update: I found out how to enable this in OS X!

Unfortunately I don't have time to post detailed instructions right now but I'll do that as soon as possible.

iBook owner 'Aleph' wrote about a different way of getting screen spanning to work on his Radeon-iBook:
His method involves patching the (original) Mac OS Rom file with ResEdit so you should make a backup of your system folder (you can do that on the same partition and keep the system CD handy in case you can't select the other system from your hard disc).
If you don't have ResEdit you can find it at
Open a copy of your Mac OS Rom file (from your iBook's original system folder in case you have tried the other method already) in ResEdit and open the resource 'gpch'. There you delete the entry with the ID 144. Close ResEdit and save the change.
Place your patched Rom file into the system folder (unless you chose to edit the original or the one in a copy of your whole system folder) and boot from that system.
You should now be able to use the second screen as an extended desktop. You might have to change the resolution with a tool such as 'Multi Resolutions' if you can't choose the desired resolution form Apple's control panel.

I have not tried this with the 17" iMac (since I only had it for a short time to experiment with) but it worked on my 700 mhz iBook and on his 600 mhz verison.
The big advantage with this method is that the brighness controls and sleep mode work correctly (since we keep the original Rom and CPU Plugins).

I experienced some problems with Apple DVD Player after this hack. When I plugged in the external screen after booting but before launching DVD Player, the Player would crash right after opening (it quit immediately without crashing the computer). When I attached the 2nd screen before boting or after opening DVD Player there were no problems. However, you can't use DVD Player with mirroring turned on (this issue existed before already when only mirroring was available so this hack actually allows you to play a DVD on an external monitor or TV). I wasn't able to turn mirroring on at all after using the DVD Player until a restart of my iBook (the control strip for mirroring was grayed out and dragging the two screens ontop of each other in the monitors control panel had no effect).

A nice thing about this hack (works with the other way mentioned below as well) is that you can build your own cheap TV adapter.
All you need is a VGA connector (Sub-D 15 pins, 3 rows), an RCA connector (also called chinch in some regions) and some shielded cable (one wire plus shield).
Simply solder the core wire to pin 9 of the VGA connector and the shield to pin 5. Then solder the core wire to the center pin of the RCA connector and the shield to the other lead of the RCA conncetor.
Now you plug the VGA adapter that came with your iBook into the iBook. Then (assuming you booted from your hacked OS 9 system) you open the monitors control panel and set the external screen to one of the PAL or NTSC resolutions. You need to tell the control panel to display all it's windows on the main screen (otherwise you won't be able to change and confirm the settings). You can do this in one of the menues (can't remember exactly where right now).
When you're done with this you can attach your VGA-Composite adapter to your TV and your iBook's VGA adapter (if you connect it before you set the resolution you might damage your TV since you put a signal on the composite-in which it doesn't expect).
To play a DVD on the TV screen you need to move the player's window to the external screen before you change it to full screen mode (and you can't use the player with mirrored screens - see note above).
The iBook also supplies an S-Video signal. I haven't tried this yet (I don't think my TV has a S-Video input). The C-component of the signal is delivered at pin 1 of the VGA connector and the Y-component at pin 2. Ground is at pin 5 (or at any other pin that is usually ground in a VGA connector - might be easier to use different ground pins if you want to build a Composit and S-Video all-in-one adapter like the one Apple sells).

I doubt that this method would work on older (Rage) iBooks since they came with a Rom version which doesn't contain the mentioned resource but if you have an older iBook it would be nice if you could try it and report it to me (

If you are familiar with the intestines of OS X I would really appreciate it if you would contact me ( even if you don't have an iBook. I really want to get this to work in OS X but I don't know enough about how the graphics system.
I think we're one step closer to an OS X solution now that we know that we just need to delete one resource in the MacOS Rom. What replaced the Rom file in OS X? Is it in the kernel? Would it be possible to use the Darwin kernel (and maybe alter it)?
Or is it possible to trick the OS into thinking that it runs on a different type of Mac? How does the OS know about the hardware?
You see there are many questions so if you have any suggestions it would help a lot if you would contact me. Thank you already!

At this point I would like to thank 'Aleph'. He contributed to a lot by experimenting with his iBook which led to the above mentioned way of deleting one resource. He invested a lot of time and effort.

Here is the 'traditional' way how you can get an extended desktop on your Radeon-equipped iBook with an external sceen connected (currently OS 9 only):
(this also works on the current 17" TFT iMac even without the problems noted with the iBook concerning the brighness controls and sleep issue)

1: Go to the Apple download site and get the MacOS 9.2.2 (about 23MB) and 9.2.1 updates (about 85MB).
2: Go to and get "TomeViewer" and "Multi Resolutions"
3. Copy your current System Folder to a different partition or disc (or make a backup so you can work on the original system)
4: Use TomeViever to extract "Mac OS ROM" from the 9.2.2 update and "Apple CPU Plugins" from the 9.2.1 update.
5: Copy "Mac OS ROM" to the System Folder you want to modify (preferably the one you copied to a separate partition) and copy "Apple CPU Plugins" to System Folder/Extensions/Multiprocessing
6: Reboot from the modified System
You now should be able to set all the options a Powerbook can use for the external display.
There are two things you should know though:
1: Your system won't be able to sleep (probably due to the older CPU Plugin).
2: The brightness controls (on the keyboard and in the Displasy control panel) are inverted and you won't be able to get full brightness. Note that you can get a brighter screen with the keyboard controls.
Another nice thing about this is that you can now play DVDs in OS 9 with external an screen or projector connected (didn't work before - DVD Player gives error upon opening)
Other than that your system should behave just as you're used to.
If you can't select the desired external resolution you can use Multi Resolutions which offers more resolutions.
You don't have to swap any ATI extensions.
If you have any comments, didn't get it to work, got it to work and have suggestions or anything like that I would appreciate your email.
Anyways, you're old enough to do things at your own risk so don't blame me for anything ;)

Here's a list of the resolutions I get displayed (I didn't test them all - let me know if you did)
(these are for the iBook - the iMac can use much higher resolutions but I don't have a list yet)

512 x 384 @ 50 (PAL), 60, 60 (NTSC), Hz
640 x 480 @ 50 (PAL), 60, 60 (NTSC), 67, 72, 75, 85 Hz
640 x 870 @ 75 Hz
720 x 480 @ 60 (NTSC) Hz
720 x 576 @ 50 (PAL) Hz
800 x 600 @ 50 (PAL), 56, 60, 60 (NTSC), 72, 75, 85 Hz
832 x 624 @ 75 Hz
1024 x 768 @ 50 (PAL), 60, 60 (NTSC), 70, 74.9, 75, 85 Hz
1152 x 870 @ 75 Hz
1280 x 960 @ 75 Hz
1280 x 1024 @ 60, 75, 85 Hz
1600 x 1200 @ 60, 65, 70, 75, 85 Hz
1792 x 1344 @ 60, 75 Hz
1856 x 1392 @ 60, 75 Hz
1920 x 1440 @ 60, 75 Hz

Note: The highest resolution I tried (due to limitations of my 17" CRT) is 1280 x 1024 @ 60 Hz.
All resolutions I tried were available with millions of colors.
You can't use the PAL or NTSC resolutions on a normal screen since they are only used for the TV adapter. With this mod it should be possible to build your own (and cheap) TV adapter. This wasn't possible for this iBook generation before since the iBook detects the used adapter with the DDC code which would be hard to emulate on a home made adapter. You can find the pinout in the Developer Notes available at Also be aware that you could fry your monitor if it has no protection (I think all newer ones do) against too high resolutions and scan rates!

This demonstrates what many people guessed before:
Apple limits the features of the iBook to keep a distance to the Powerbook.
Since this seems to be a software lock in the driver it should be possible to modify the existing drivers. Anybody want to do that for me? ;)

Reader Sven Sewitz started a petition about monitor spanning as a regular feature.
You can find it here:
I encourage everybody to sign this. That might be the only chance to keep this working in future OS releases.

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