The Low End Mac Mailbag

iMac Rev. B Nightmares, Thousands vs. Millions of Colors Performance, and Unsupported Leopard

Dan Knight - 2007.12.11

iMac Rev. B Nightmares

From Seann Giffin:

I'm trying to get a Rev. B Bondi revived, and I'm having some issues. It will only read an OS 9 or higher CD, and if I partition the hard drive, it generates a scrolling error.

I only have one, so there's no abundance of spare parts, and I live in a small Canadian town in the Niagara Region, so there isn't a surplus of used iMacs or parts.

I'm trying to install OS 8.6, and I've had an enormous amount of trouble doing so! I won't bore you with all the details, but if you want the history, it's all in the Apple Discussion Forums.

Any help or insight you have would help me a lot!


Seann (EvilSupahFly) Giffin


Thanks for sharing the link to the Apple forum. It sounds like you've got the iMac from Hell, and it looks like you're taking the right steps.

I only just learned that the classic Mac OS can have problems with partitions larger than 8 GB. Until now, I only knew of it an an OS X problem. To play it safe, we now suggest making the first format 7 GB, and you have to install whatever version of the Mac OS you want to use on the first partition. OS X won't let you install to a bigger partition on these iMacs, but OS 8.x and 9.x won't stop you. Problem is, if any System files end up past the 8 GB mark, you could end up with an unbootable Mac, so if your hard drive is bigger than 7 GB, you should partition it so the first partition is no bigger than 7 GB to avoid this problem.

You should be able to run any version of the Mac OS from 8.5.1 through 10.4.x, but you'll have to use either an iMac installer for 8.5.1/8.6 or a universal install CD. If your installer is for something different, such an an iBook, PowerBook, or Power Mac, that could explain your problems. Also, your keyboard problems will probably be best solved with a new keyboard - PC USB keyboards will work and are dirt cheap, although some of the marking are a bit different.

You've already covered the hard drive and firmware in the Apple forum.

Finally, there's bound to be someone with a similar Mac in the area - St. Catharines, Niagara Falls, Welland, Port Colbone, Fort Erie (my roots are in the area, but all of my relatives seem to be Windows users). Maybe ask around on our Mac Canada list.


Actually, it boots as long as the hard drive is not partitioned. As soon as I do that, it breaks, even if the first is less than 8 GB.

The drive itself is a 60 GB. The OS 9 CD is a universal and can see the whole thing. The other CDs are OS 8, 8.1, and 8.6 universal installs as well, but the thing won't read them.

I'm tempted to give up on it and just hit up eBay or something.

Of course, not owning a car makes part sourcing difficult, but I thank you for your advice!


I'm definitely stumped by this one: You can only boot from an OS 9 CD, nothing earlier, and not if the hard drive is partitioned. Very strange.


My wife wants me to give it up, and I sometimes want to, but part of me won't go down without a fight and this is turning into a fight I can't win.

My pride won't let me give up.

Early G3 Mac 8 GB First Partition Issue

Dear Dan:

The 8 GB limitation that exists on older Macs may be a limitation of Open Firmware. I mean, on NewWorld Macs the Mac OS ROM file is read using Open Firmware, also all Macs read the BootX file when booting Mac OS X by using Open Firmware.

Yuhong Bao

Interesting thought, but this only seems to impact early G3 Macs, not pre-G3 PCI Macs that would also have Open Firmware. Of course, it could be that nobody noticed the problem because hard drives were a lot smaller in those days.


Thousands vs. Millions of Colors

From William R. Walsh:

I saw your response and link to a blog posting stating that running with thousands instead of millions of colors could make a video card run faster and cause a Macintosh to use less resources. I don't have any benchmark results to offer, but I can suggest that reducing the color depth on an older Mac with older graphics hardware will result in a very obvious performance increase.

The more colors your video card has to display, the more work your video card's GPU and supporting components must do. On newer cards the issue of color depth is a moot point - a new video card running at thousands of colors won't be much if any faster than it is at millions of colors. But older cards with more limited processing speed and memory/RAMDAC bandwidth will pick up in speed if they don't have to display as many colors. The amount of picture data would likely remain the same, but the amount of color data decreases, which causes video memory and GPU utilization to go down . . . sometimes quite dramatically.

In the days of video cards that were little more than dumb framebuffers, reducing the amount of picture and color data that had to be shuffled around could free up some CPU resources. But nearly all relatively new (within the last ~8 years or so) video cards have at least some form of onboard acceleration.

I think the advice offered on the blog posting is targeted primarily at users of old Macintosh systems and video cards. It would be true no matter what version of the Mac OS is in use. It won't make much difference on newer systems or video cards. It's a good, free trick to try if you want to squeeze just a little more performance out of an older Mac with older video hardware - just about everything will look pretty much the same even with thousands of colors available instead of millions.



That blog specifically addresses Leopard users, and a lot of the author's comments don't make any sense to me. He says that changing to thousands frees up RAM, which isn't true of any Mac, vampire video or dedicated. He says it impacts swap memory, which it would only do if it impacted RAM usage - but vampire video on Intel Macs uses a fixed amount of system RAM.

He goes on to say that he's running Leopard on a 1.67 GHz PowerBook, which probably only displays 18-bit color to begin with, so he's not going to see any real difference on his display - but the PowerBooks had dedicated video processors and video memory. As I said, it's very confusing that he talks about things that simply aren't relevant to any modern Mac.

I can imagine that a Pismo or an early Power Mac G4 with ATI Rage Pro video might be snappier with 16-bit graphics, but in no case is it going to have any impact on system memory usage or swap space.


Leopard on Unsupported Power Macs

From Adam Potts:

I have Leopard currently running on 2 of my 3 unsupported Macs.

The first is 800 MHz Quicksilver [with] a single stick of 512 (so the 2nd computer would be more usable). Video is ATI Rage 128 Pro, 16 MB, built in year 2000, Core Image listed as "Software", and Quartz Extreme is not supported. Installed via hacked installer (changed a simple No to a Yes and burned a new DVD, should be able to install on any G4 with the correct firmware) straight to the internal drive via a $30 off-the-shelf DVD internal burner. Running two internal drives, 30 GB Quantum Fireball (OEM Apple drive) and a 20 GB Western Digital.

All apps requiring Core Image don't seem to work (correctly): Front Row works, but has no video, will play audio though. I haven't tried Time Machine, as all my files are stored on my B&W 350 MHz G3 which is set up as a server running Tiger and using Sharepoints. DVD Player does work, as does VLC, though VLC will sometimes drop frames, especially if there's anything else running.

Computer 2 is Dual 450 MHz G4 (it may be an upgrade, the computer was obtained for free from my work, and I don't ask too many questions when people are handing me free stuff, other than "does it work?") with 1.12 GB RAM. Video is ATI Radeon 7500, 32 MB, built in year 2001, Core Image support is listed as "Software", Quartz Extreme is supported, 2nd video card is PCI ATI Rage 128, 16 MB Core Image also listed as "Software", Quartz Extreme is not supported. Both video cards are driving 19" Acer LCDs at 1280 x 1024 @ 75 Hz Installation was the same as above, off-the-shelf DVD burner straight to internal drive using hacked install DVD. Running 2 internal drives. Seagate 250 GB Partitioned into 30 GB boot disk and 200+GB file storage disk. System profiler lists it as 128 GB capacity, but it recognizes and uses all the available space anyway. 2nd drive is Western Digital 40 GB. As far as apps go, the same things work and don't work on both computers.

Both computers run significantly faster than they did running Tiger. I also don't have problems with them hanging on restarts anymore, and the 450 will even wake up from sleep, which neither would do under Tiger. I haven't tried putting the Quicksilver to sleep, as I've had it busy ripping my DVDs to the server since installing Leopard, though when it fell asleep during the install process, it hung, and I had to restart. The graphics on both computers seem to be a bit choppy at times, though not any more than Tiger was. Overall, Leopard seems to be much more stable than Tiger ever was, and even loaded down with running apps is faster than a fresh install of Tiger.

To date, Leopard has been the most pleasant computing experience I've ever had. The only downside (other than apps requiring Core Image) is the complete lack of any easy way to input data into iCal (what? no drawer? it was ugly, but at least it was useful). The upside to not having a Core Image capable video card is I have an opaque menu bar by default. It's also fun to play around with the Dock files to get rid of that ugly grey thing that comes standard.

I did not even attempt to install Leopard on my G3, as from what I've read, the actual processor architecture isn't supported or can't handle it. Plus there's a lot of valuable data on there I don't want to lose.


Thanks for the field report. I'm planning on digging my G4/450 dual out of storage soon, loading it up with every version of OS X I can lay my hands on (I have the Public Preview and versions 10.0 through 10.4 at present), and leaving a partition for Leopard as well. I plan to make it a testbed where I can play with memory configurations, swap out video cards, etc. without worrying about messing up my main computer, a G4/1 GHz dual. It's good to read how well Leopard runs on such old hardware.


Leopard on PowerBook 550 and eMac 700

From Richard Jordan:

Hi Dan

A while ago I wrote in and told you of my experience installing and using Leopard on a PowerBook Ti 550. I have since then installed Leopard on an eMac 700 MHz and have been running both now since the middle of October.

I thought I would give you an update on their Leopard usage and, to be honest, they work very well. Both are running 10.5.1, and although a little slower (as you illustrated in the benchmarks you sent me) they are perfectly usable . . . however . . . there are some limitations:

The eMac and the PowerBook will no longer allow video chats through iChat. iChat does not see the external iSight camera as able to run video chats; it will however let you use it's internal mic for audio. This is very weird, as under Tiger, the eMac and PowerBook handled these video chats perfectly. If you have a solution for this, I'd love to hear it - it's one thing that I really do miss.

Another issue is neither machine can use the screen share feature over iChat with a Mac mini 2 GHz Core Duo running Leopard, I'm not sure why, as I can screen share over a network from the PowerBook to the Mac mini. I can then connect to the same Mac mini using an iBook 1.2 GHz and iChat over the Internet, so I know it's not down to my Internet line. Looks like iChat really is built around compatible machines and not just updated code.

One major issue I have found on the eMac is it's graphics card from time to time locks up coming out of a screen saver. I am guessing this it a limitation of the graphics card and Leopard's Core Graphics libraries. A forced restart with the power button is the only way to reboot.

Apart from that, everything seems to be fine, and the only thing I really miss is video chatting in iChat, which I would love to fix.



Thanks for the update. Apple has an extensive guide for troubleshooting the iSight camera, but since it works in Tiger but not in Leopard, it doesn't seem it would be a hardware problem. Perhaps connecting the iSight webcam after Leopard is running will help.

I haven't got a copy of Leopard yet, but I've done a little Googling. Ted Landau notes on MacFixIt that for screen sharing to work, both Macs must be running Leopard, must be running iChat, and must have Bonjour enabled if they're on the same local network. No idea why Screen Sharing is failing, but it might have to do with older, less powerful graphics processors.

You're the second to report lockup problems with the first generation eMac. The other reader said that if his eMac goes to sleep, the only solution is to power it down and start it up again. Maybe that's part of the reason Apple didn't support 700-800 MHz Macs.


Leopard Running on Dual 800 G4 Power Mac

From Terral Cochran:

I installed via Target Disk Mode from a Quad G5

What unsupported Mac(s) have you installed it on? G4 Dual 800

How much RAM? 1.5 GB

How fast a CPU, and what brand, if it's an upgrade? Stock

What video card does your Mac have? Nvidia GeForce 2 Twinview

Which installation method did you use, a modified installer or installing from a supported Mac? Installed to internal drive on G4 via Target Disk mode.

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Dan Knight has been publishing Low End Mac since April 1997. Mailbag columns come from email responses to his Mac Musings, Mac Daniel, Online Tech Journal, and other columns on the site.

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