Archive for February, 2010

Monthly Aphorism: On Choosing Jobs

  • This project is doomed, but you can have fun for the next two years.

That’s how a friend of mine introduced the IBM Digital Video Disk project. She was absolutely right on both counts; before the project went down the toilet, I wrote the killer hard-real-time track-following code that:

  1. Laid a one-micron laser beam dead-nuts on a one-micron data track while the one-foot-diameter floppy disk rotated at 3600 rpm with a few hundred microns of eccentricity.
  2. Acquired and mapped the aforementioned spiral track’s eccentricity from a cold start, so Step 1 would actually work.

Everything I’ve written after that has been pretty straightforward.

The project was a Skunk Works deal, running well outside the mainline IBM planning hierarchy, and had plenty of capital & expense budget to go around. Unfortunately, the technical foundation was a bit, mmm, flaky; one of the marketeers insisted that some combination of primary light colors would project black on a screen.

It eventually imploded, of course, pretty much on the timeline she expected. For some reason splitting the assets off into an independent company and moving the neutron-star remnant to California made sense to the higher-ups. They offered a few key guys good jobs in sunny CA (the rest of us got token offers that didn’t get any takers), the core group lasted another few years, and then the thing went into a black hole.

Would it surprise you to know the spinoff was called “Disc-O-Vision”? Bear in mind this was before the whole disco music era, but, still … and it’s entirely unrelated to the MCA laser disk of the same name, independently developed somewhat later.

Word had it that the single most valuable asset was a patent on slapping digital data on a disk: that patent yielded a quarter-cent royalty on every pressed CD ever made. I have no way to know whether that story is true, but you can do the math.

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Arch Linux: Initial Setup

Herewith, some general notes on getting Arch Linux installed & tweaked on my rather bizarre set of desktop hardware. The bottom line is that it pretty much works, with very few quirks, right out of the carton. Search for previous posts detailing most of the things discussed here.

Hard drive partitioning on /dev/sda:

  1. Dell Utility
  2. Windows XP
  3. Dell Restore
  4. Logical -> Extended
  5. Swap
  6. Xubuntu 9.10 (recently installed desktop)
  7. Xubuntu 8.10 (last year’s desktop)
  8. Arch Linux installation (replacing Ubuntu 9.10 trial install)

The trick is to have enough partitions lying around that you can do a complete installation without clobbering your previous version. Then, when you’re happy the new one works, just change the Grub boot default and you’re off & running.

Follow the Installation & User Guides, which walk you through most of the choices and situations.

I did not allow it to install Grub, as I already had it set up and didn’t mind some manual tweakage.

After the installation, I added this stanza to the existing Xubuntu 9.10 grub.cfg file to boot the new Arch installation; the old menu.lst file has vanished with the new Grub. On a 1600×200 LCD, I need VGA=792 in what used to be the kernel line to get readable characters.

menuentry "Arch Linux on /dev/sda8" {
	insmod ext2
	set root=(hd0,8)
	search --no-floppy --fs-uuid --set 108a6b1b-1628-47dd-ab84-7a13be82590b
	linux /boot/vmlinuz26 root=/dev/sda8 ro vga=792
	initrd /boot/kernel26.img

The Arch installation completes with a reboot to a naked root command prompt. Everything beyond that happens only at your command.

Add your personal user, add the wheel group to your ID, then uncomment that line to enable super powers when you edit /etc/sudoers.

I had to do pacman -Syy before any installs worked. I found no advantage to powerpill rather than pacman.

Various programs:

  • rpcbind & nfs-common
  • alsa-utils
  • cups

The modified entries in /etc/rc.conf, which is where much of the system configuration & daemon startup occurs:

eth0="eth0 netmask broadcast"
gateway="default gw"
DAEMONS=(syslog-ng hal network rpcbind netfs nfs-common cups crond)

The Terminus font looks better than whatever the default is, but maybe that’s just me.

The eth0 line is all it takes to set up a static IP address. Zowie!

The gateway line aims all Internet traffic at my firewall router.

The DAEMONS line starts up a variety of services. I have these:

  • hal – required for XFCE and others
  • rpcbind – for nfs network file shares
  • netfs – similarly
  • nfs-common – nfs client
  • cups – network printing

I added my usual nfs mounts to /etc/fstab, got the service startup order correct in rc.conf, and it’s all good.

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Improved Sherline Way Bellows

What with all the milling going on lately, I decided to replace the crusty bellows on the Sherline mill. The previous design worked reasonably well, but I’ve had a few tweaks in mind for a while.

Herewith, a PDF file with some Sherline Bellows – Improved:

  • Color coded lines so you know which way to fold them!
  • Unlined side up for a neat look
  • Fits on Letter and A4 sheets
  • Taping cuts and hints

The PDF page size is about 8×10 inches; call it 204×280 mm. Print it without scaling and it should just barely squeak onto the sheet. If you don’t have a full-bleed printer, the tips of the sides may get cropped off, but you can extrapolate easily enough.

Some assembly required:

  • Cut it out
  • Fold the central valleys (red) first, flatten it out again
  • Fold the central ridges (blue) next
  • Pleat the whole thing into a half-inch tall stack
  • Squash it into a neat package to harden the folds
  • Fold the tips along one side
  • Fold the tips along the other side
  • Squash the folds again
  • Make the saddle cuts & fold the tabs
  • Apply double-stick tape as noted (some on back)
  • Install on your cleaned-up mill
  • Admire!

The tip folding is the trickiest part. Basically, flip the first tip from a ridge to a valley, then chase the little transition folds into place. Repeat for each tip along that side, then do the other side.

It gets easier after you fumble around for a while.

My nimble-fingered daughter has offered to fold ‘em for you. Stick a few bucks in an envelope and mail it to me; we’ll mail back two folded sets (two each, front and rear bellows) for your amusement. Kid’s gotta earn her college money somehow…

Address? Go to the database and search for my amateur radio callsign: KE4ZNU. Cut, paste, that was easy.

For the do-it-yourselfers, start with the PDF file in the link above. That’s the easiest way to get the correct scaling. The tabs on the ends should be 4.0 inches across on the printed page.

Rear Bellows

Rear Bellows

Front Bellows

Front Bellows

Here are some 300 dpi PNG files, but you’re on your own for scaling.

If you want the original Inkscape SVG files, drop me a note.



Sink Drain Pop-Up Lever: The Rot

Rusted Drain Rod

Rusted Drain Rod

The drain in our black bathroom(*) stopped working: the pop-up drain seal didn’t pop up.

I finally wedged myself under the sink, with my feet in the shower stall, and removed the operating rod. Turns out that we replaced the countertop and sink (nine years ago; nothing lasts) and the drain used plastic pipe.

Except, of course, for the operating rod that sticks out into the drain. That’s chrome-plated steel, evidently with a few plating imperfections, and the end had simply rotted away. I suppose there’s a small chunk of steel decomposing in the trap.

How much would it have cost to use stainless steel in this corrosion-prone application? Or good old brass (“contains an ingredient known to the State of California to cause cancer or birth defects”)?

After a brief moment of consideration, with my feet still in the shower, I pushed the rod through the bearing ball so the other end stuck out by about the right amount and replaced it in the drain.

Swapped Rod

Swapped Rod

Yeah, there’s an icky rusted end hanging out there in mid-air, but the next person under that sink will understand exactly what’s going on…

(*) It’s the size of a large closet with wraparound black ceramic tile, a white tile shower stall, and a wall-sized mirror over the sink. We painted the walls and ceiling white, installed an ersatz gray granite counter top (it’s laminate, not anything spendy) with a shiny white sink, and it’s all good. The original half-century-old grout is in fine shape: some things really do last!



Tire Liners

After putting Mary’s newly covered seat on her Tour Easy, I replaced the tire liner in the front wheel; the previous tube had gone flat, as mentioned there, due to erosion from the end of the liner.

Here’s what the taped liner looked like: smashed as flat as you’d expect from 100 psi applied evenly over the surface. The tube had a rectangular imprint on it, with what looked like minute abrasions, around the outline of the tape. Nothing major, but it shouldn’t ought to look that way.

Taped tire liner

Taped tire liner

I rolled that liner up, popped it in the Bike Tire Stuff drawer and replaced it with a Slime liner. This picture shows the ends of the two liners: the brown one (bottom) is about 90 mils thick in the center, the Slime liner (top, fluorescent green) is 60-ish.

Tire liner comparison

Tire liner comparison

As nearly as I can tell, I’ve never had an abrasion flat with a Slime liner, while various other brands have caused troubles.

I broke the edges of the Slime liner with a bit of sandpaper, just to see what that’ll do. Most likely, bad things, seeing as how I’ve never done that before…


Ubuntu 9.10 Karmic: FAIL FAIL FAIL

Soooo, for the last several days my main desktop system, recently installed with Xubuntu 9.10, has come up without networking services. The eth0 network interface is there, the (static!) IP is correct, Web browsing works… but NFS shares aren’t mounted and, upon poking around, other vital system services weren’t started.

Worse, networking can’t be manually started, either, and there are no diagnostic log messages.

Sometimes rebooting helps, sometimes it doesn’t. The problem is definitely timing-related, so sometimes pausing before signing in makes it work. Sometimes it doesn’t.

Come to find out that Karmic has revised how system services get started during boot. The intricacies are lost on me, but the old Unix-style /etc/init.d/ model is now obsolete. Documentation on upstart, the replacement, is sketchy at best.

We’re to type sudo service mumble start|stop|restart when we want to do things manually. Oh, maybe only start and stop have been implemented; everything else is defunct, but you can’t use the old method, either.

Except that something in upstart 0.6.3-11 is broken / different, to the extent that system services no longer start up properly. Evidently that upgrade happened here in the very recent past, part of the usual system update routine. I do this manually, but there wasn’t any heads-up notice mentioning “Oh, by the way, this update will kill your system”, so I just installed it.

Downgrading to -10 resolves the problem for many people, not including me, but that is not regarded as an actual fix. The older version has similar problems and downgrading just pushes the symptoms somewhere else. Part of the problem is that logging doesn’t (seem to) happen from upstart for any of the affected services.

Now, Linux distributions started as a way to bottle up various combinations of upstream programs in known-good configurations, so that we end-user types didn’t have to go through the Linux From Scratch effort. That model seems largely dead; each major distro now applies so much floobydust to their combination that any resemblance to the upstream programs is purely coincidental.

Like, for example, did you know that you’re probably not running OpenOffice, but Go-OO? Never heard of it? Me, either. Do the obvious search and see what you’ve not been told. Hint: Mono is still optional.

Long ago, in a universe far away, I actually enjoyed beta testing software. These days, I just want it to work; I have other things to do. It’s painfully obvious that Windows isn’t the answer, but it’s becoming evident that (at least) Ubuntu has lost sight of the “it just works” goal.

When vital parts of the system (like, for example, networking and system service startup) Just Don’t Work, something has gone badly wrong in the distro’s QA process. Yes, some problems remain hard to find, but when they’re reported (by other folks; I’m not first in line by any means) something should happen muy pronto.

When a desktop environment (like, for example) KDE can’t handle two independent monitors, but has all manner of glitzy 3D effects, the development effort has wandered off into the bushes of irrelevancy. The fact that KDE can claim to have fixed 10,000 bugs in the 4.3 release is not, to my mind, much to brag about.

To quote the immortal Iphigenia Deme, “That’s obscene-gerund enough!

Right now, I have a column to finish and ship, with another right behind. With any luck, this system will hang together long enough to get those done, at which point I must devote some time to finding out which, if any, distros have a better recent track record.

Some early fiddling indicates Arch Linux, which is sort of like Linux From Scratch with bigger and sorta-kinda snap-together pieces, should do the trick. Most important: it’s agnostic with respect to which desktop environment you pick, unlike the GNOME-oriented Ubuntu chassis that sorta-kinda allows you to bolt on KDE or Xubuntu bodywork.

Quick summary of what’s needed: separate X sessions, right-hand session on a rotated-to-portrait monitor, Wacom tablet pinned to the left monitor, left- and right-handed trackballs. This configuration was fine in Kubuntu 8.04, got flaky in 8.10, and fell apart after that.

There may well be upstream problems with some of those pieces, which generally isn’t something a distro can fix. I contend they could better apply their resources to fixing such problems than screwing up something else.

More to follow…


DVD Player External Li-Ion Pack: A Pleasant Surprise!

A friend mentioned a sale at (likely gone by now) that offered an Initial RB-270 9 V, 5.4 Ah lithium-ion battery pack, with a built-in charger, for $16. The pack was intended to keep a DVD player alive for long enough to avoid back-seat mayhem on long trips (for those toting undisciplined brats, anyway), but I saw it as a plug-in replacement for the NiMH AA-cell packs I’ve been using with the HTs on our bikes.

The NiMH cells have been a major disappointment, as described there and there and there, with barely 1.5 Ah of capacity from nominal 2.4 Ah cells.

Much to my surprise, all three of the Li-Ion packs delivered pretty nearly their advertised ratings. I varied the discharge level, but they’re all quite close…

Initial External Li-Ion packs

Initial External Li-Ion packs

It looks like the packs include an internal regulator and over-discharge monitor, as the voltage is bar-flat right up to the point where it drops to zero. I’m mildly surprised at the regulator; I’d expect that they’d just deliver whatever the cells were producing, rather than waste any energy in the regulator.

Notice that the 200 mA rate produced a lower total capacity than the 1 A rate. I’m guessing that’s power lost in the regulator over the protracted run time; 4.9 Ah at 200 mA added up to nearly a day of testing, far over the “up to six hours play per charge” rating.

Let’s see: 5.4 Ah @ 6 hours makes the nominal load about 900 mA. So it delivered maybe 4.8 Ah at 1 A. Not what’s claimed, but much closer than those Tenergy NiMH cells.

Next steps:

  1. Butcher the nice coily-cord cables to add Powerpole connectors that will click right into the bike radios
  2. Take one apart to see what bypassing the regulator would entail