I took a trip out to my previous employer’s business to check out an interesting find he stumbled upon in a purchased lot of computer equipment. Among other official Apple-branded machines and workstations were several apparently custom built 3U rackmount G4 servers. I took a bunch of pictures documenting the meticulous overhauls that were done in readying the new machines for about 8 hard drives, plenty of PCI cards, and proper cooling. Judging by the labels left on the converted towers, they were intended to be used as ProTools workhorses, mixing audio and piping effects around someone’s once-elaborate pro audio setup. Aside from the unique form factor (for a Mac-based server, anyway) and the sheer geekiness of such an undertaking, the power controls and cooling system are of particular interest.

The one really interesting bit of circuitry in the whole system is one tiny Marathon power board, which connects to the relocated front panel board of the original tower. Several years ago, Marathon Computer offered rackmount conversion kits for Apple’s G3, G4, and even iMac systems. These enclosures appear to be made by I-Star, despite similarities to Marathon’s PowerRack kit, though pictures and documentation about Marathon’s kits are now extremely hard to find.

To keep the system and its veritable wall of hard drives running cool and trouble-free, large fans were employed in conjunction with a simple, off-the-shelf fan controller which combines the feedback from multiple fans into one monitoring port, complete with overheating alarm and adjustable temperature settings (via jumpers).

For completeness, a SCSI card and stealth serial port were added, leaving room for ProTools PCI audio cards. In its day, this was a screaming system that bested even Apple’s top PowerMac offerings, and would still make for a fairly respectable server today. Someone clearly spent many hours getting the physical layout and electrical systems “just right”, which I thought was well worth preserving and sharing.

Looking through Apple’s technical documentation on the MacBook Air revealed that the 80 GB drive it ships with is a Samsung HS082HB 1.8″ (4200 RPM, 8 MB cache) ZIF model, a departure from the Toshiba-dominated iPods. With the same size of only 5mm thin, I wouldn’t be surprised if these started showing up in iPod Classic 80 GB models — it seems likely, given that the low end Classic is the thinner of the two and exactly 80 GB in capacity. It seems many drive manufacturers are jumping on the 1.8″ form factor bandwagon now, which will inevitably result in cheaper pocket-sized storage that will be enjoyed by all.

In the years before Xcode and Mac OS X, there was CodeWarrior, an IDE and compiler of legendary speed. It has since fallen by the wayside, but you can bring back old Macintosh development memories with this humble Metrowerks style folder icon, ready to paste onto any project to give it that classic Geekware feel. Download Now

If you’ve formatted a bootable hard drive on an Intel Mac (or have perhaps been tinkering with the wholly unsupported OSx86 project) and later decided to put the drive to use under Windows XP, you might find that you’re unable to format the disk, with Windows Disk Management claiming the device is a “GPT Protective Partition.” You can’t format it, partition it, or even assign it drive letter. What gives?

The secret is that the GPT scheme protects itself from being read and possibly erased by utilities or operating systems which aren’t able to correctly interpret it. Until just recently, I wasn’t aware that a filesystem even had such a capability. I was under the false assumption that a utility running externally of the drive in question could always format a detected disk, no matter the filesystem in place. I doubt it could withstand the raw formatting power of DBAN, but it was enough to confuse Windows XP.

How can the GPT scheme be undone? Typically, software that can create it can also destroy it. In my case, Leopard’s Disk Utility application was able re-partition the drive as follows:

• Boot a Leopard DVD (retail or OSx86) and choose your native language at the first screen.
• Run “Disk Utility” from the “Utilities” menu and highlight the offending drive on the left.
• Navigate to the “Partition” tab, choose “1 Partition” from the Volume Scheme popup menu, select your new desired format (or “Free Space”), and make sure to click the “Options…” button
• From the “Options” screen, you can choose between GUID Partition Table, Apple Partition Map (for PowerPC Macs), and Master Boot Record. Choose MBR, and click OK.
• Click “Apply” to partition the drive using the more common MBR scheme, and thus completely erase all trace of the GPT partition.

Once the partitioning is complete, you’ll be able to format and use the drive under Windows XP, Mac OS 9, or any other system incapable of comprehending GPT Partitions.

Whenever I get a new stick of RAM for my Mac or PC, I’m always eager to just plug it in and start using it to its fullest, but having worked on hundreds of computers and encountering dozens of bad memory modules has convinced me that thorough testing is a must. While off-the-shelf PCs can run a copy of the free Ultimate Boot CD tool to perform RAM tests, Macs are a little bit more complicated in this respect. If you’ve purchased AppleCare for your Mac, it comes with a bootable TechTool Deluxe disc, but you’re otherwise left to your own devices when it comes to hardware tests.

Fortunately, with a little preparation right now, you can boot your Mac into Single User Mode and do a complete RAM test in the future. While you can run the necessary software in a fully-booted system, I recommend doing testing in Single User Mode where there are far less programs loaded in memory, and less chance of an important system component getting corrupted if your machine freezes or kernel panics — common symptoms of bad memory. A modified Mac OS X boot CD would be ideal, but that’s another post for another day!

Download Memtest

The testing setup isn’t terribly complex; I’ve taken the liberty of putting together an installable package which will put the Memtest utility into your /usr/bin/ folder. Memtest is a Unix command-line program that does the memory testing, and is the Mac equivalent of MemTest86.

Memtest Usage

To run memtest on a new memory module, first shut down your computer and install the new chip. (Some helpful guides for doing this can be found at iFixit, if you’re unsure of the exact steps.) Ensure the chip is firmly in place, close up your machine (or don’t, if you’re a pessimist), and power it on while holding down the Command and S keys to force Mac OS X to boot into Single User Mode. Once you see a black screen with white text, you can release the key combination. After all the system logging is done scrolling past, type memtest all 2 to test all memory two times. Two passes should be enough to detect any blatant problems, but I wouldn’t hesitate to let it run for hours on end if I suspected an intermittent memory problem (memtest all). When complete, you should be greeted with “All tests passed” if your new RAM is in good condition. If your system locks up or freezes indefinitely during the test, you may have a bad memory module on your hands.

2/16/12 Update: Memtest is still working under Mac OS X 10.7 Lion.