Big Mess o' Wires

Ah, Maker Faire. It’s part garage inventions, part Burning Man reruns, part techno-supermarket, and all awesome. Can it possibly be a year already since Maker Faire 2009, where BMOW was featured in Wired, Slashdot, Digg, etc. and I talked myself hoarse in a 48-hour marathon of CPU conversations?

This year I headed back to the Faire as a visitor rather than an exhibitor, so I’d actually have a chance to see the cool stuff I missed last time. The show has actually grown since last year, which I didn’t think was possible, but they annexed a neighboring county or something and added even more exhibits than before. This event is big, big, big. It’s almost too big. After a few hours my brain was fried, and I just couldn’t appreciate all the awesome stuff anymore. I think there were at least three different robot death-matches, ten 3D printers, and dozens of Arduino add-ons.

My major goal for the show was to do SparkFun’s SMD soldering class. I made a beeline to the SparkFun tent as soon as I arrived, and after a short wait, I sat down with eight other solder artists to construct SparkFun’s Simon kit. Here are a few pics of the setup:

After a short introduction, we jumped right in, and I soldered the first tiny IC without any problems (1 mm pin spacing). But at step two, a surface-mount capacitor, the wheels came off the cart. I just couldn’t get the cap to stick to the pad, after at least ten attempts, and eventually I overheated the cap to the point where it disintegrated. I sheepishly asked for a replacement, which took a while for them to find, and it took even longer for me to successfully solder it in place. Everyone else in the class was well ahead of me, and I was beginning to feel like a dummy.

After a few more steps, I soldered in the battery terminals, and was ready for the first major checkpoint: test for 5V. Unfortunately, this was when I discovered I’d soldered the battery terminals onto the wrong side of the board! One of the instructors took it to a rework station to fix it, which took a mysteriously long time, and when he came back I had a burned board with one trace lifted off the PCB. Argh. Eventually I was able to repair it with a jumper wire, and it passed the 5V test. But we were now an hour and a half into the class, and many of the other people were already done, just awaiting their turn to have the Atmega on their Simon board programmed.

I kept working, while the people on either side of me debugged their boards. After programming, one neighbor had a board where only two lights worked, and another had regressed and no longer passed the 5V test. While they debugged, I moved steadily forward, and eventually finished the assembly. At this point, both SparkFun’s main and backup Atmega programmers broke, and they were unable to program any more boards. Not a great ending to the class.

Ironically, the Atemga itself with its 0.65 mm pin spacing (I think) was actually pretty easy to solder. Just tack one corner, blob solder onto all the other pins while ignoring shorts, and then suck away the excess with solder wick. I’d say it’s the small size of the components that makes soldering them challenging, less so than the spacing of the pins. Take a look at these photos of my finished board. Some of those little surface mount passive elements are soldered in at awkward angles, but it’s the best I could do. Look at the size of my finger for reference. That tiny capacitor to the lower-right of the Atmega in the second photo is only about 1 mm long, and 0.5 mm wide… yikes! These parts make a grain of rice look giant. It’s tough to even see these things clearly. In the photo you get a pretty clear view, but with the naked eye that tiny cap is just an unidentifiable grayish speck, and whether it’s soldered properly is impossible to tell.

After the class, I wandered the Faire for most of the day, seeing lots of pretty cool stuff, but nothing that really stood out in my mind as exceptional. I enjoyed getting a chance to program an Altair 8800 using the front panel switches, but overall I think the show was just too much steam punk exploding fireball mechanical giraffe sensory overload.

As I prepared to leave at the end of the day, I stopped by the SparkFun booth once more, and they’d managed to get their Atmega programmer working again. I asked if they could program my board before I left, so I could attempt to debug the inevitable problems later at home. They did, but instead of a debugging puzzle, I got the happy “beep!” of a working Simon board. No debugging needed!

HUGE thanks to the SparkFun guys. The soldering class was great, and my instructors Matt and Matt were full of help and encouragement. The class itself was a fantastic bargain, since they only ask for a $20 donation, which goes to local science-related education projects. The Simon kit sells in the SparkFun store for $25, so this was like getting a $5 discount off the kit *and* free hands-on training. Can’t beat that!

Random project for a Saturday afternoon: a guitar amp in a Cheetos Crunchy can. I followed a modified version of Make Magazine’s cracker box amp design, which uses an LM386 power amplifier and a few passive components. The amp has separate crunch (gain) and volume controls, is powered from a 9V battery, and delivers half a watt through a 2-inch speaker hidden inside the can. The whole thing went together in a couple of hours, and most of that was planning how to arrange the parts.

Now I just need to learn how to play guitar.

A fantasy-land for hardware nerds like me is hidden in a former Silicon Graphics building in Mountain View, California. Despite living only a few miles away from the Computer History Museum, somehow I’d never found the time to visit there before today. It was well worth the visit, as the museum is stuffed to the roof with amazing artifacts from computing history. Even though the majority of the exhibits were closed due to a renovation project, I still got to see all kinds of wonderful techno-treasures.

Here I am standing inside the Cray-1 supercomputer. In 1976, this machine was as high-performance as you could get, a 250 MFLOPS monster that cost $5 million and required 115 kW of power.

I thought BMOW had a lot of wires, but brother, when I saw this Cray, my jaw dropped. Just look at this thing! See all that blue stuff on the inside? Those are individually-routed wires, stacks of wires, piles of wires, mountains of wires, every single one neatly-labeled with an ID code.

The Cray-1 is a hollow cylinder, about 6 feet tall, 4 feet in outside diameter, and 2 feet in inside diameter. Most of that space is consumed by about 2000 circuit boards, and the rest is positively stuffed with wires. I stared at the circuitry for a long time, trying to estimate the wiring density, and decided the machine has somewhere on the order of 100,000 individual wires.

Here’s a close-up, which gives you a sense of the massive scale of the wiring. It’s just insane.

When I finished ogling wires, I took a look at Babbage’s Difference Engine No. 2. Designed by Charles Babbage in the 19th century, this massive mechanical marvel computes tables of polynomials. It supports up to 7th-order polynomials, and computes results to 30 decimal places. The desired polynomial is entered by setting a series of gears, and then a crank is turned by hand to generate the results, one at a time. Babbage designed it all on paper, and built working versions of small pieces of the mechanism, but it remained a purely theoretical invention for more than a century after his death. Some doubts remained about whether the machine would actually have worked, had it been built.

In 1985, the Science Museum in London set out to build a working Difference Engine No. 2, from Babbage’s original design drawings.  The project took 17 years to complete, facing all sorts of setbacks, but in the end the machine worked as Babbage had intended. The finished difference engine is on display at London’s Science Museum, but a duplicate was made for project benefactor and Microsoft millionaire Nathan Myhrvold. Myhrvold agreed to lend his duplicate to the Computer History Museum, to share and educate.

Some of the other computing artifacts I got to see:

• Deep Blue, the IBM chess computer that defeated World Chess Champion Garry Kasparov in 1997.
• The first mouse- a block of wood with a momentary push switch mounted on it. Created by Doug Engelbart at PARC in 1964.
• A 10MB hard disk platter, 3 feet in diameter, from 1974.
• An original Apple I, the kit-built ancestor of the Apple II. A hand-assembled logic board, keyboard, and power supply, mounted on a plywood plank.
• A restored and working PDP-1. During the restoration, volunteers were able to retrieve data originally stored in the core memory decades earlier.

Too much awesome stuff!

BMOW logo T-shirts are now available! Check the link on the left sidebar. Get one and show a little electronics geek pride! Available in six colors, $18.99 each, operators are standing by to take your order.

These are the same T-shirts that I and my assistants wore at the Maker Faire last year, where many visitors were disappointed they couldn’t buy a shirt for themselves. I only made six in that first run, but my friends who got them still seem to wear them a lot (maybe a little TOO much). I wore one at Disneyland last year, which led to a long conversation about CPU design with a guy I met while in line for Mr. Toad’s Wild Ride. Electronics geeks are everywhere.

If you’re not reading the BMOW comments, you’re missing half the discussion. Matthew Simmons asked if there’s a comments feed, and the answer is YES. I’ve added links for both the posts and comments feeds to the left sidebar. I often make follow-up comments to my own posts, with progress updates or related discoveries, and lots of smart people provide great suggestions and commentary. If you normally read the BMOW site with an RSS reader, be sure to add the comments feed too so you don’t miss out.

After reading about BMOW on Slashdot last week, Jim George offered up some Augat wire-wrap boards and old-school ICs that were sitting around gathering dust. His care package arrived today, just in time for a weekend of tinkering.

There are four Augat boards, each one about 7 x 2.5 inches, or about 25% of the area of the BMOW system board. Each board has space for five columns of skinny DIP 0.3 inch chips. The undersides (not shown) are pre-populated with about 600 wire-wrap pins.


Jim also threw in a few dozen wire-wrap tags, which are just little plastic cards with holes in them that can be placed on the pin side of the board, showing where the chips are placed and marking the pin numbers. I can’t believe I built all of BMOW without these. They seem like such an obvious thing. Staring at a featureless green board with a thousand pins on it, it’s easy to get disoriented without markers like these.

To round out the package, Jim also included a handful of 7400 series logic chips, and other related parts:

• 74AS181 x 5, 4-bit ALU
• 74ALS374 x 11, 8-bit register
• 74F323 x 7,  8-bit shift register
• 74F299 x 6, 8-bit shift register
• 6116 x 3, 2K x 8 SRAM
• Intel 8255 peripheral interface adapter

Thank you Jim!