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Computer-memory lane

2013 June 23
by Matt

Technology tip, as much for my own future benefit as anything: don’t put mismatched memory in your computer.

Not quite one-and-one-half years after purchasing my first laptop, which has since proved itself both reliable and almost indispensable, my MacBook suddenly became reliably unstable. Maybe two weeks ago now, it began repeatedly freezing up. (Mac users: that gray “you need to restart you computer” thing; Windows community: think “BSOD.”) Something had suddenly gone very wrong. I’m pretty sure that if it still applied under OS X, the “Sad Mac” icon would have been very much in evidence.

I tried all of my DIY, “home care” remedies. Updated the OS (with some difficulty, as this process was consistently resulting in freezes). Ran Disk Utility. Ran TechTool Pro.* Finally, all else having failed, I booted up from an OS disc and stripped the hard drive bare. As my laptop is just a secondary Mac, this wasn’t quite agonizing, but I could have done without it… Particularly as, about one minute into reinstalling the OS from original media onto a blank hard drive, my ‘Book froze again.

At this point, I felt I had established two things at least: 1) I was probably dealing with a hardware problem, and 2) it was time to seek professional help. Fortunately, there’s an Apple Store in Westlake, and I was able to get a same-day appointment at the “Genius Bar.” Frankly, I always find the Apple Stores a little creepy (and don’t even get me started on Crocker Park), but I greatly appreciate having them around. On the rare occasions when I need help, they seem invariably ready to provide useful, prompt and friendly assistance, gratis.

Such was the case here. After listening to my story, and plugging some diagnostic doohicky into my MacBook, the man behind the Bar concluded that either the logic board had failed… or, just possibly, mismatched memory was giving the system fits. I bought my MacBook used, and I think I requested an upgrade to 2 GB of memory as part of the order; at any rate it arrived with what were apparently memory modules from two different manufacturers. It worked fine, anyway, for more than a year… but as I could potentially run the computer with just one of them, it was free and relatively simple to test whether a memory conflict was at fault before contemplating a new logic board. So, after returning home, pulling up instructions online and then hurrying down to the hardware store for the tiniest Philips-head screwdriver they had… I pulled out one of the memory modules and then resumed the previously interrupted reinstallation of OS X. It worked.

I remained suspicious, gradually restoring software little by little, but after a week without another freeze I concluded that mismatched memory had probably been the issue. So, not wanting to rely on “just” 1 GB of memory forever, I ordered a new, matched set, and decided I might as well max out with 4 GB total. Which makes for an interesting milestone…

…because this marks the first time one of my computers has as much memory as my very first Mac had hard drive space. That’s right, in 1998 the Power Macintosh G3 (desktop model) enjoyed four gigabytes of disk space, and 15 years later my MacBook now has that much space for RAM. (Its hard drive is something ludicrous like 160 GB.)

This becomes even more amusing to me because it also reminds me of a long-ago conversation with one of the engineering students in my college dorm, and his prediction that expanding computer memory would eventually make the hard drive obsolete; I distinctly recall his giddy enthusiasm for the prospect. “We’ll run from cache!!” Bwa-ha-ha!

So far, the hard drive hasn’t quite disappeared, even with memory capacities that would have left those 1990s students scratching their heads about what you could possibly need more space for; the advent of digital media libraries was still in the future back then, along with 15 years of software bloat.

Still, giddy 1990s engineering student’s prediction might actually be starting to come true all the same; it may be a bit of a technical question, which I can’t quite answer with certainty. But if the hard drive has not completely vanished, it does seem to be quietly clearing out; the current MacBook Air has dispensed with spinning disks and relies entirely on flash storage, and of course the iPad and iPhone never shipped with anything else. I don’t know exactly how much this does or does not fulfill the dream of “running from cache;” my intuition would be that flash storage is not so fast as modern RAM, but might in some sense be zippier than 1990s RAM. Maybe

In any event, it looks like childhood hopes for hover-technology, cold fusion and holography are going to remain behind schedule… but however you slice it we do have considerably more amazing information technology than Back to the Future II imagined, so that’s something.

* Now, I don’t have the newest and greatest version, but still… wouldn’t mismatched memory making the system unstable be exactly the kind of thing that TechTool should pick up on, or at least flag as a possible source of trouble? “C’mon, man.” Update 6/24: Just this morning, Micromat announces TechTool Pro 7, for which “We’ve taken almost 2 years to develop one of the most advanced memory tests in the industry that will help technicians and users alike diagnose and isolate this common, but often missed issue.” Better late than never, then.

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