Sep 012007

Well… I’ve had some interesting issues this week.  Murphy must be looking down on me.

O2: RM5200 CPUs with PROM 4.0

I recently purchased a RM5200 CPU module for my O2.  Now, my O2 at the time came with a R5000 180MHz CPU, and had PROM rev 4.0.  After handing across AU$100 on the new CPU module, I later discovered my PROM didn’t recognise the CPU, instead, it emitted the message:

Not supported CPU type. PRid<impl>=0x28

PANIC: assertion failure (IMPOSSIBLE) in file cache_mi.c at line 203

… via serial console.  The seller had tested the CPU in one of his boxes (accidentally left one of the riser connectors attached to the module) prior to me picking it up, so I knew the CPU worked.   He hadn’t struck this problem before — which I suspect is because 99% of his customers would have IRIX 6.5 installed (the PROM gets updated during the install process).

My problem, I don’t have a complete set of IRIX.  I downloaded IRIX 6.5.30 from SGI’s SupportFolio website, plonked some files out of the first overlay CD on my TFTP server and managed to netboot IRIX into a miniroot, however I lacked the foundation CDs, thus couldn’t perform an installation.  Thankfully, J. Scott Kasten was generous enough to email me the flashinst utility and IP32 PROM image, which I used to update my PROM to v4.18.  It’s a shame that SGI haven’t considered releasing a minimal IRIX miniroot with flashinst so that us Linux users can update our PROMs without downloading >2GB of tarballs and spending an entire weekend trying to figure out how to turn tarballs into an IRIX installation.  I’ll post up how I netbooted IRIX and updated the PROM later.

In any case, my O2 is back up and running… flying along at 300MHz.  Just to upgrade the RAM (it already has 36GB+4GB HDDs)  and it’ll be a sweet machine (as far as O2s go).  I’ve since left feedback on the item, and posted the surplus riser connector back.  (I got the CPU module from “octane_king” on eBay Australia, who has a few of these available as a buy-it-now auction, if people are interested.)

Building a new headlamp

I broke my LED headlamp on a recent camping trip … it was one of these 3-LED jobs, that ran on AAA batteries, and could either work as a handheld torch, or clip onto a bracket.  The torch still works, but it is now an ex-headlamp, a pain in the arse if you’re trying to carry things.

Not happy with what’s on the market, I got a bright idea to make my own.  Basic idea, I’d use a hard hat to mount the LEDs on and conceal the electronics under the shell.  As an added feature, the headlamp was intended to incorporate a light-dependant resistor (CdS cell) which was to drive a inverting schmitt trigger, so that the headlamp could switch-off if there was sufficient light around (e.g. I stepped indoors).  I’ll be posting about this in detail later too.

I had all sorts of fun getting the hard hat… I was after a full-brim one, since the others look bland, and the full brim one would also give me more surface area for mounting components.   My first problem was not knowing the right key words, I had tried “wide rimmed”, mining, and numerous other keywords without success.  Once I had the right keywords though, I did discover a couple of suppliers here in Brisbane (such as Blackwoods at Carole Park).  They’re still insanely rare in this part of the world.

Now that I’ve got everything, I started building it last night.  Trouble is, the CdS cell has gone walkies, and I just know it’ll turn up if I buy one.  I also didn’t count on the curvature of the hard hat being a problem — I planned to use double-sided tape to attach the battery packs and PCB to the underside of the shell.  Turns out I’ll need to drill a hole and use nylon nuts & bolts to attach these.  That said… I have my headlamp partially working now — sure, I look like I’ve just stepped off a building site, but it’s functional (still some fine tuning to do).  I intend to make use of it at Riverfire tonight, as well as those late nights when heading to/from university.

Anyway, right now I’m in procrastination mode… I need to resume studies on a telecommunications subject pronto, so I better pull my finger out and get to work. 😉