Intel iMac Tips

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On June 6, 2005, Apple announced that all new Macintosh computers would use Intel processors instead of the PowerPC that had been used for many years. At that time, Apple indicated that the first of the new machines would not be available until mid 2006.

On January 10, 2006, Apple dropped the first shoe about six months early. They announced that the first Intel based Macintosh computers were shipping. The first models were the 17" and 20" iMac models that had just been refreshed in October 2005. The Intel iMac based models are essentially the same as the Oct 2005 G5 version except with an Intel Core Duo CPU in them. I bit and ordered one the next day. It arrived on January 16, 2006. My somewhat contorted reasoning for this move is described at my Upgrade Tips page.

The Intel based iMac computers need an entirely new object code set to run. Apple accommodates this two ways. First, newly released applications (and the whole OS itself) are complied as a "Universal Binary." This just means that the entire object code set for BOTH PowerPC and Intel processors is included in the application. Each computer can pick which kind of code it wants to run. The other method is through an object code translator called "Rosetta." This translator attempts to translate PowerPC object code to Intel object code on the fly. It caches the result for later use so that the speed impact is not huge. Testing by others indicates relative speeds to 40 to 80%. This makes the older applications usable even if they do run slower until the software supplier has a chance to recompile and re-release his code as a Universal binary.

When Apple dropped the bomb on the world that the first ones would ship in January 2006, many of the software vendors were certainly caught off guard and they were not ready with their Universal binaries. This makes Rosetta all the more important.

Rosetta works in most cases, but there will always be cases where something odd was done in a particular piece of code so that Rosetta cannot swallow it.

The primary purpose of this page is to list my experience with various applications that I use and other notes about the hardware itself.

Hardware Notes

Overall, this is a great computer, very nearly ideal for most users. I have some personal issues with it, but these may not be problems for others. Gamers will find it to be a competent game machine, but those that want the most possible performance will have to look to much more expensive iron. Those that like to tinker inside will be very unhappy. This is an all-in-one closed machine that isn't easily upgradable, but then again, it comes very well equipped and really doesn't need upgrades, except for RAM.

Installed RAM. The computer comes with 512 Meg of RAM. This is enough for PPC systems, but does not appear to be enough for this Intel based system. Perhaps Rosetta makes heavier demands on RAM. In any event, as soon as the green wedge disappears in the Activity Monitor's RAM display, the computer dives into virtual memory hell and gets very unresponsive.

These systems REALLY NEED more RAM. I finally got 1.5 G installed and it made a world of difference. Virtually all of the beachballs went away and switching between applications is now virtually instantaneous. Running with a small "standard" set of applications open (Mail, Safari, Activity Monitor, LaunchBar and some dashboard widgets) uses up 750 M, or half of the total. A slightly larger set running on a G4 system uses less than 300 M. This Intel based Macintosh simply demands more RAM than previous PPC based systems.

Speed. As long as there is free RAM available, the computer is very responsive. Many CPU intensive applications seem to be able to load up both CPUs. The only applications that I have found that are CPU bound are video related, HandBrake and iDVD. I keep an Activity Monitor CPU indicator running all the time, unless the computer is grinding on video, it always has CPU left to burn.

Screen Size. This is a 20" version. For me, the screen is actually too big. I can't quite get it all in the lower (close range) lens of my bifocals at one time. Others may find that the expansive screen is very handy. For me, 20" is all I can visually deal with.

Screen Height. In this version, Apple changed the mount away from a standard VESA mount to a custom one. This was probably done to allow a thinner enclosure, but it makes it much more difficult to replace the stock foot with an adjustable mount. I would like the lower the whole thing so that the screen is closer to the keyboard. I would not have to tip my head back a little to see the top of the screen in my bifocals.

Screen Brightness. I had to turn the display brightness down to the minimum setting so that it didn't overload my eyes. The thing is basically too bright. Contrast and viewing angle are outstanding. This is a top quality display.

Airport Implementation. Initially, the Airport seemed to be having trouble with download rates. The rates that I got are were half of what I should get. Other computers in the house did much better. See An Airport Network Performance Evaluation for the details, look toward the bottom of the page. The 10.4.6 MacOS upgrade provided new drivers so this problem is fixed.

Expandability. This is not so much of an issue with me, but I need to make the observation that the iMac has minimal expandability. The user can add RAM (quite easily, the instructions are etched on the bottom of the foot) but nothing else. There are "no user serviceable parts inside." For users that like to tinker inside and buy bits and pieces to customize their computer, the iMac is NOT the computer that they want. It comes the way that it is and there is little that can be done about it. One buys an iMac for what it is out of the box. I find that the computer is well enough appointed with features such that upgrading is not necessary. When I need a lot more features, I'll buy a whole new computer with much more smoke and hand this one down to somebody else.

32 Bit Addressing. The Intel Core Duo is a 32 bit processor. It has lots of smoke, but due to the 32 bit address path width, it cannot address memory beyond 4 GB as an absolute maximum. The iMac also holds only 2 DIMM memory modules. Currently, there are only 1 GB modules available which limits the maximum memory to 2 GB. Even when 2 GB modules become available, they may not be supported. The system consumes some memory addresses beyond 3 GB so that even with 4 GB installed, the system is unlikely to be able to use all of it. 2 GB is plenty of RAM for most users, more than actually needed. However, with virtualization, it is possible to run different OS's at the same time. Each will need its own memory space and with 2 or even 3 different OS's running at the same time (OS X, Windows, Linux etc), 2 GB could get a little thin. The difficulty of adding upgrades may make upgrading the CPU too difficult or impossible for this model. If you think that you'll ever need more than 2 GB of RAM, then you might want to wait for the next batch of 64 bit Intel processors to appear.

Update 29 Oct 06. Around Aug 06, Apple did upgrade the CPU to the 64 bit Core 2 Duo. It's a little faster and supports up to 3 GB RAM. This is apparently a limitation of the Intel 945 chipset used in the iMac.

Power Consumption. The iMac Core Duo is a very efficient machine. It uses a processor designed for mobile applications and therefore doesn't draw much power or shed much heat. The computer draws only 71 watts by measurement when working hard with adequate display brightness. Turning the display brightness from minimum (which is still bright) to full (which is outright blinding) increases the total power drawn to 99 watts. Many high performance PC's draw two or three times the power and there need noisy cooling fans to keep them from overheating.

iMac Core Duo Power Consumption
Screen Brightness CPU Load Notes
Screen Black 2 33 53 It takes about 33 watts to run the computer at light load without the screen backlight running, another 18-20 watts to run the computer hard
Screen Dim   53 71 Just lighting the screen to minimum intensity takes about 19 watts
Screen Bright   80 99 To run the screen at full brightness takes another 28 watts or so

Noise. The low power consumption of the computer allows it to get along with little fan noise. There are fans, they do run, but at very low speed so that they make hardly any noise at all. If I put my ear right above the vent across the back, I can hear the fans. If I sit in front of the iMac in a quiet house, I cannot hear the fans. Even while the computer is working hard, the fans do not ramp up. While doing a recent firmware update, the notes said that the fans would come on full during the update. They did and they were loud. If they ever did come up to speed in normal use I haven't heard them yet.

Boot Camp

Boot Camp is Apple's implementation of an environment that allows Windows XP to dual boot. After using Boot Camp, it is possible to boot either Windows XP or Mac OS X. I cannot comment about Boot Camp at all because I have no investment in Windows, no copy of an XP install disk and no desire at all to waste some disk space.

Firmware Updates

There are been at least three firmware updates for the iMac. The iMac was the first Intel Mac out of the gate and it is somewhat expected that some firmware tweaks would be required. One firmware update is only needed to provide support for Boot Camp, another is only needed to support languages that write from right to left. The SMC 1.0 update modifies the behavior of the System Management Controller. I installed it and noticed no difference at all.

Rosetta Compatibility

Rosetta is Apple's way of letting the Intel computer execute code written for the PowerPC. It works well enough most of the time, but not all PowerPC code was written cleanly enough to allow Rosetta to run. These programs will need to be re-released, either in Rosetta compatible form or as a Universal Binary so that Rosetta isn't needed.

There are other places to find more of this information, I am listing ONLY the stuff with which I have direct experience. You can also look at the Apple Discussion pages. There is a long thread there where folks are listing what does not work as of the day posted. The list is long but will probably get shorter as each software vendor catches up.

Having older software that requires Rosetta is not a bad thing. Most of it is just fine the way that it is and if it never gets updated to Universal Binary it won't be a bother at all, that is until such time that Rosetta itself is no longer supported. This should not be an issue for many years. These computers are fast enough so that even if the application runs at half of its native speed, most users will not even notice it.

I've broken the software down into two simple lists, that stuff that DOES work, either as a Universal Binary or through Rosetta and the stuff that DOES NOT work for some reason. Note that ALL of OS 10.4.4 Tiger is compiled as a Universal Binary so Apple supplied software (with one exception) is not listed.

Software That Works On The Intel iMac
Title Version Mode Notes
AbiWord 2.4.1 Rosetta Free OS word processor, a good program
Acrobat Reader 5.0.5 Rosetta  
Acrobat Reader 7.0.5 Rosetta  
Adobe Reader for Palm OS 3.05 Rosetta converts .pdf files for display on a Palm device
AppleWorks 6 Rosetta Not supplied with the computer, newer version can be purchased for $79, may be Universal
AutoCat 3.08 Rosetta makes an image of a disk with just aliases. Very handy for indexing archives that are stored elsewhere.
Balthisar Tidy 0.5 Rosetta checks for correctness of html
BBEdit Lite 6.1.2 Rosetta general purpose text editor
Camino 1.0b2 Rosetta excellent web browser
Camino 1.0.3 Universal excellent web browser
EasyDraw 1.9.0c Rosetta Drawing tool, reads MacDrawII, MacDraw Pro and Claris Draw files.
EasyDraw 2.0.0 Universal  
Excalibur 4.02 Rosetta Spelling checker, LaTex and html aware
Fetch 4.0.3 Rosetta FTP tool
FireFox 2.0 Universal web browser
Solitaire Till Dawn X 1.5 Rosetta Outstanding Solitaire Game
Myst IV, Revelation   Rosetta  
Myst V, End of Ages   Rosetta Either copy installed game from a PPC or download the Intel updater (from or The game runs but messes up window positions when it quits.
GraphicConverter 5.7.3 Rosetta excellent graphic file conversion/modification tool
GraphicConverter 5.9.3 Universal excellent graphic file conversion/modification tool
Handbrake 0.7 Rosetta DVD ripper
Handbrake 0.7.1 Universal DVD ripper
HP Scan 7.7.2 Rosetta HP all-in-one scanner application
iCab 3.0.2 beta Rosetta web browser
Internet Explorer 5.2.3 Rosetta sub-standard web browser
LaunchBar 4.1 beta 3 Universal application launcher, very handy
Link Checker X 1.3 Rosetta web site link checker
Missing Sync for Palm OS 5.1.2 Universal Palm OS sync tool. If you have a Palm OS device, you NEED this software. Replaces all the Palm Desktop, conduits and iSync stuff completely and it works.
MPEG Streamclip 1.1 Rosetta Converts MPEG2 video AND audio into other formats
MPlayer OS X 2.0 Rosetta generic video player
OpenOffice 2.0 Universal Office suite, needs X11 installed
Opera 8.51 Rosetta web browser
Sound Studio 2.2.4 Rosetta Audio digitization tool, works very well
Synchronize! X Plus 3.0.1 Universal disk synchronization/backup tool
Transmit 3.2.1 Rosetta FTP tool
iStumbler release 96 Universal 802.11b/g network finding tool
AirTraffic Control Widget 1.3.0b2 Universal 802.11b/g network finding tool
Pocket Tanks Deluxe 1.00c Rosetta artillery game
Loony Labyrinth 3.0.1 Rosetta pinball game, runs but is performance challenged
MacStumbler 0.75b Universal note that there is a non-universal version also called 0.75b which DOES NOT work
Logitech Control Center 2.0.0 Universal  
APGrapher 1.0 Universal Graphs airport performance characteristics vs time
Flip4Mac Universal Dump the MS WMV player, use Flip4Mac instead

Some of the stuff in the table below has been updated and you might find it also in the table above, but in a newer version.

Software That DOES NOT Work On The Intel iMac
Title Version Notes
Flip4Mac 2.0.2 WMV player replacement, installed versions don't run, newer installers won't install
Windows Media Player Plugin   Safari is Universal, the WMV plug in is not. Rosetta cannot translate a plug in to a Universal application. If you really want Safari to play WMV movies right now, select Safari and Get Info. Check the box that says to run under Rosetta. The WHOLE application will then run under Rosetta and then the WMV player will run.
Pocket Tanks Deluxe 1.00b tries to start, then dies
HP Scan 6.3.4 Tries to work but fails
NeoOfficeJ 1.1 OpenOffice port for Mac OS X. Doesn't need X11. tries to run but doesn't quite make it.
NeoOfficeJ 1.2 won't install
Airport Client Monitor 1.0 starts but doesn't ever start the graphs
Airport Management Utility 1.0 complains that the computer needs to be upgraded to an obsolete version of the Airport software and then quits.
MacStumbler 0.75b doesn't display any networks, note that the updated version that DOES work is ALSO called 0.75b
iStumbler release 94 doesn't display any networks
Air Traffic Control Widget   no response
AP Grapher 0.5 declares an error
Air Stumbler 1.3 doesn't find any networks
AirPort Radar Widget 1.0.2 scans forever
Logitech Control Center 1.6.2 preference pane won't run, wants an upgrade. If your preferences were set on a PPC system and transported over with the Migration Assistant, then the preferences still work but you can't change them.

An iMac Performance Evaluation

I ran some tests on the Core Duo iMac, the G4 PowerBook and the G3 iBook to see what the difference in performance was for a typical user task, encoding a CD. I chose "Red Moon" by Peter Kater for this test. It was the one that I grabbed off the CD rack without looking. This CD has 3611 seconds of music on it.

I ran this test a couple of ways. The first was a straight encode from the CD to 128 kbps AAC. I timed the encode and recorded the approximate CPU utilization. Then I copied the CD to a folder on the disk and then copied the tracks to iTunes as AIFF. I recorded the time it took to read the disk, but not the time it took to move the files to iTunes. I then encoded from disk and recorded that time. Based on the times for encoding I could calculate the "rate" by dividing 3611 by the encode time. iTunes displays a rate, but it tends to vary, I wanted an average rate. The average rate that I came up with was always within the range of rates reported by iTunes.

The iMac has a slower CD (8x) than either the PowerBook or the iBook (24x). The 24x CDs are fast enough to feed the slower computers so that the rates from either the optical or hard disk were similar. The iMac is clearly being held back by its slower CD. The iMac also did not fully utilize it's CPUs while the two slower computers pegged at 100%. From this data I can also infer that the iMac is 4x faster than the PowerBook and 18X faster than the iBook.

iTunes Encoding Performance
Computer Encoding from CD Copy to disk
Encoding from Disk CPU speed relative to iBook Notes
Read and Encode
Rate CPU utilization Read and Encode
Rate CPU utilization
iMac Core Duo
2 GHz
236 15.3 50% 319 167 21.6 60% 17.9 Optical disk clearly holding back the CPU. Still may be hard disk speed limited.
PowerBook G4
1.25 GHz
410 8.81 100% 274 409 8.83 100% 4.4 CD faster than the iMac, not optical disk bound
iBook G3
500 MHz
1828 1.98 100% 260 1791 2.02 100% 1.0 CD even a little faster than the PowerBook
Totally CPU bound

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© 2006 George Schreyer
Created 21 Jan 06
Last Updated December 25, 2006