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A few weeks ago I came across this interesting thread in the MacNN forums: A Guide to MacBook RAM Upgrades.

According to that thread, certain models of MacBook Pro (pretty much all models after the “late 2007″, or MacBookPro3,1) can be upgraded to more than their officially supported 4GiB RAM, some models supporting 6GiB, others 8GiB. Not one to blindly trust the first online source I saw, I did a bit more research and it seemed that a number of people had had success upgrading their machines to 6GiB RAM and OWC are even selling 6/8GiB upgrade kits for such machines.

As the price of 4GiB SO-DIMMs is fairly reasonable, I decided to upgrade my “late 2007″ model from 4GiB to 6GiB (the maximum that would work without severe performance degradation). As I was already a little suspicious about the RAM I had installed, I decided to replace the existing pair of 2GiB SO-DIMMs with new 2GiB and 4GiB modules. The price for the pair was just over £130 (~$210), which I thought was pretty reasonable.

Installation was straightforward – remove the battery, unscrew the memory door (using a Philips #0 screwdriver), pop out the existing RAM and replace it.

After booting up, “About This Mac” displayed the following:

In the three weeks since the upgrade the machine has been rock solid, even with over 10GiB RAM allocated (the joys of running several virtual machines on it). Definitely a recommended upgrade.

A few days ago my daughter’s 8GB third generation iPod Nano refused to power on. After a bit of investigation on my part it seemed as if the battery had given up the ghost – the iPod works perfectly when the sync cable is plugged in and connected to a computer, but the minute the cable is removed, it powers off.

Being out of warranty (it was purchased about 16 months ago – let me not start ranting about batteries that fail after such a short period of light to medium use), I looked around for repair options. Replacement batteries are fairly easy to come by, but the Nano isn’t the easiest piece of hardware to disassemble. Having learned the hard way, I’m really not a big fan of repairing mobile phones and similar devices myself – I always end up snapping a piece of plastic or bending something beyond repair. Taking that into consideration, I decided to look online for someone to do the battery replacement.

Apple themselves will replace the battery for the princely sum of £46.13 (including shipping), which seems just a tad pricey – a new fourth generation 8GB iPod Nano costs only £107. The well-known Juice Your iPod will perform the service for a much more reasonable $32 (excluding shipping), but it seems a little silly to ship an iPod half way around the world to have its battery replaced. I then came across UK iPod Repairs, who’ll do the replacement for a reasonable £30, excluding shipping. I’ve placed an order with them and will be sending them the iPod tomorrow. According to the site, I should get the repaired item back by the middle of next week – expect an update once that’s happened.

Update:Unfortunately the problem wasn’t the battery, it was the logic board. As a replacement would’ve cost in the region of £80, I ended up buying a replacement fourth generation Nano for her (£105).

I recently had to create a number of bootable USB flash drives to install and update systems that don’t have local CD-ROM drives. Of course, I could’ve booted the systems using PXE, but thought using USB would be quicker… How wrong I was.

After struggling for several hours with a flash drive that refused to boot no matter what I did, I discovered an interesting fact – most bootloaders won’t boot from flash drives that have 2048-byte sectors. Of course, the flash drive I was using had 2048-byte sectors… Using a flash drive with 512-byte sectors worked perfectly first time.

Depending on operating system, it may not be that easy to tell the sector size of the flash drive. If using a Unix system, you should see something useful in the kernel ring buffer (displayed by dmesg) when you insert the drive.

A non-bootable drive will display something like:
sd 9:0:0:0: [sdh] 258687 2048-byte hardware sectors (530 MB)
or
sd0: 505 MB, 126 cyl, 64 head, 32 sec, 2048 bytes/sect x 258687 sectors

A bootable one will look something like:
sd 11:0:0:0: [sdh] 2061816 512-byte hardware sectors (1056 MB)
or
sd0: 1006 MB, 1006 cyl, 64 head, 32 sec, 512 bytes/sect x 2062328 sectors

The one year warranty on my MacBook Pro is due to expire in a few weeks, so I’m thinking of investing in AppleCare to extend it by a further two years. AppleCare is rather expensive though, particularly for laptops – $399 (£ 279) for my model if bought from the online Apple Store.

There are a number of sellers offering the same plan for roughly half price on eBay, $199 Buy It Now. Positive feedback for these sellers is close to 100% and, as AppleCare is a worldwide warranty, it seems like a smart move to buy from them, rather than from Apple. Read the auctions more closely and things start to sound a little fishy though. The majority of the sellers who sell a lot of AppleCare packages provide the serial number electronically, rather than providing the retail package or any official paperwork from Apple. Only the serial number is required to activate the warranty, but surely the retail package should be available, if requested? Although the serial number provided may activate the warranty, how do we know that it wasn’t generated by a serial number generator?

I think in this case I’m going to be more prudent and pay a little bit more to buy an AppleCare plan that comes in the proper retail package – there are a number of sellers on eBay offering them and they’re also available from a number of reputable online retailers. The prices aren’t as low, but at least I’ll be more comfortable that I’m buying a legitimate product.

With our recent acquisition of a number of Sun Ultra 60s, Jonathan and I have been doing a fair amount of CPU swapping to max out our machines.

Something odd that we’ve both noticed is that when we put a 450Mhz CPU into a machine that we didn’t receive with a 450Mhz CPU, it wouldn’t boot up. There’s no mention of CPU speed jumpers in the service manual, so we both put it down to different motherboard revisions, phases of the moon and the lack of a chicken sacrifice.

A few days ago I discovered the Sun 450 MHz UltraSPARC-II Module Upgrade guide, which details the CPU speed jumper settings for the Ultra 60 (see pages 3-5 and 3-6). Bah. Why doesn’t Sun bother documenting these things in the service manual?

I’ve been network booting SPARC systems for a while now, ever since my last run in with a faulty floppy drive on a SPARCstation 2. NetBSD makes it easy – the standard installation includes a diskless client filesystem which can simply be extracted onto the boot server. It wasn’t quite so straightforward with FreeBSD, so here are a few pointers…

My boot server is running NetBSD 3.1 and I booted FreeBSD 6.2, so if you’re using different software you may need to make some adjustments. YMMV.

1. On the boot server, configure rarpd(8) as usual, adding the entry for your machine’s MAC address to /etc/ethers. For example (for a machine called test02):
   08:00:20:b2:2f:b6 test02
2. Extract the FreeBSD base fileset to the appropriate location on your boot server (for example, /export/install/fb62_sp64).
3. Extract the FreeBSD GENERIC kernel fileset to boot/ in your diskless filesystem.
4. Within your diskless root, symlink boot/GENERIC to boot/kernel (boot/GENERIC is a directory that contains the kernel and its modules).
5. Put boot/loaders from the diskless filesystem into your tftp root directory and symlink it to your machine’s IP address in hex. For example, the filename for 192.168.1.92 is C0A8015C.
6. Export your diskless root filesystem via NFS and add the necessary dhcpd.conf stanza. For example:
host test02.pimp.org.za {
hardware ethernet 08:00:20:b2:2f:b6;
fixed-address 192.168.1.92;
option host-name "test02";
option root-path "/export/install/fb62_sp64";
}
7. Boot your machine – “boot net” from the PROM should do it.

A few tips:

• It’s normally a good idea to update the machine’s OpenBoot PROM to the latest release. Old PROMs often have subtle bugs.
• Extracting FreeBSD filesets is simple:
cat 6.2-RELEASE/base/base.* > /tmp/base.tar.gz
tar -xzvpf /tmp/base.tar.gz -C /export/install/fb62_sp4


Update: Fixed incorrect command to extract sets (thanks John Messenger!)

Thanks to a lead from Mark, I now have even more Sun Ultra 60s – another five, for the princely total of R450 (about $60). They are of varying hardware specification, but I have 1x300Mhz CPU, 2x360Mhz CPUs and 2x450Mhz CPUs, somewhere in the region of 2.5GiB RAM and a few 4 and 9GiB disks. All the machines have dual width Elite3D framebuffers. All in all, a pretty good deal

My plan is to put together at least two dual CPU machines, one running FreeBSD and another probably running OpenSolaris. *sigh* If only NetBSD supported SMP on 64-bit SPARC systems.

Yes, it’s true – I’ve switched to a Mac running OS X as my primary home workstation. For the past few years I’ve been running NetBSD on sparc64 systems, but felt that it was time for a change. Something in particular that’s really annoyed me is that Firefox still isn’t stable on 64-bit big-endian platforms – I had to resort to running it on a NetBSD/alpha system and displaying it locally.

It’s still early days, but I’m impressed with how everything Just Works under OS X. It’s not quite a traditional Unix system (NeXT always was a bit different, NetInfo for example), but a Mach kernel, a mostly-FreeBSD userland and a pretty GUI is good enough for me Of course, I’m still keeping my Ultra 60 running NetBSD as my second head – just need to get Synergy configured so that I can talk to both machines with a single keyboard and mouse.