Tag Archives: vintage tech

Vintage Technology: Laser and Video Discs

Laser and video discs 2

OMG—Is that Once Upon a Time in China IV?

Well, yes, but that’s not what we’re here to talk about. We’ve dug up specimens of two very different types of high-tech video playback media from decades ago— and it’s much more interesting than you might guess. Continue reading Vintage Technology: Laser and Video Discs

Photomask Mirrors


At our local Silicon Valley electronics surplus shops and electronics flea market, we frequently come across all sorts of bizarro semiconductor manufacturing paraphernalia. Here is one of those types that we have written about before, in our coaster project:

Photolithographic masks, or photomasks are clear templates used in semiconductor manufacturing. Typically, they are made of UV-grade fused silica and have a highly intricate chrome metal film pattern on one side.

The most commonly available masks are test patterns used for calibration, as production masks are guarded carefully. This particular one dates back to 1983!


Now looking inside at it, it’s hardly a mask at all. It’s nearly fully silvered—perhaps a mask pulled out before the etching step of its process.


If you look at an oblique angle, you will find a few incredibly detailed patterns, and some printed on markings. This one is marked “5.1 INCH ARRAY” across the top and “1447 3-OCT-83-13. 5” across the bottom.


So, what to do with them? Since they don’t have the neat patterns that made those coasters so cool, we used some truss-head screws to mount them to the wall.


And here we are then, using a couple of photolithographic mask as bathroom mirrors! (With a couple of units at different heights for different-height people.) It solves a couple of problems at once: how to display the beautiful ephemera of semiconductor manufacturing, and what to do about a soulless little extra bathroom at our shop that didn’t come with a mirror.


Oddities at the Electronics Flea Market

eFlea July 2013

Today was the monthly Electronics Flea Market in Cupertino, and we came across some gems this month.

Above, an AN-OIL-IZER. The seller said her geologist father used it for testing oil purity.

It’s described in patent number 3182255, a device for capacitively testing lubricating oil (e.g., engine oil) for contaminants, by looking for changes in its dielectric constant. To use it, you place a drop of the oil in the holder, and the ball bearing into that drop of oil.  The bearing is held down by a leaf spring, keeping it indexed against the holder.  This forms an oil-filled capacitor between the ball bearing and a lower curved plate that is insulated from the bearing. The capacitance will vary as the dielectric constant of the oil changes due to contamination.  It comes with two ball bearings, as well as oil samples for calibration.

eFlea July 2013

The E-Z-Code Jr. is a tool for learning morse code: when you draw the “electric pencil” through the slots, it crosses contacts in the correct spacing to make the characters. It also has a hinged telegraph key which can be tucked away below the device.

eFlea July 2013

The seller of the E-Z-Code Jr. told me that the thing I really should be photographing was this magnetron. It is a beautiful old piece of hardware, with its wave guide and high-power tube.

eFlea July 2013

We found a book on Magnetic-Bubble Memory Technology. We also saw a book on tube delay memory.  We’re not sure if these are a step up from the single-bit flip-flop memory in our Digi-Comp II.

eFlea July 2013

I’d love to see the circuit diagram for the Cosmic Energy System by Psy Herabel [sic] Health Town, Inc.!  (Sadly, their domain no longer seems to be active.)

Dr. Nim

Our friend Brian (the designer of the EBB driver board which is used in the Eggbot) recently posted this picture on twitter, with the following caption:

Kids found 1966 ‘computer’ ‘game’ in the closet and LOVE it. Dr. Nim always wins. Our future may be OK.

Dr. NIM was designed by the same engineer, John Godfrey, who designed the Digi-Comp II, and it was manufactured in the mid-1960’s by the same company, E.S.R. Inc. It is even described in the same patent as the Digi-Comp II and works in the same manner, using mechanical flip-flops triggered by marbles. Only, to play the ancient game of Nim instead of doing binary calculations. We were very curious about how Brian came by one, and asked for more information. He wrote what follows:

We were on a week long vacation in Michigan. We rented a large house on the shore of Lake Michigan near Traverse City. The house looked like an extreme example of 1960’s decorating—nothing has been updated since. (Large tables with built-in ash trays, shag carpet, an old radio that had a “magic eye” that lit up when your FM radio station was ‘in hi-fi stereo’, etc.) And, in the closet with the games, was one called Dr. Nim. Us adults never gave it a second glance until one of the older kids noticed that it said “computer” on it, and pulled it out to see if she could get on Facebook with it. My ears perked up, and when I saw the front cover, I couldn’t stop playing with it. Which is not surprising considering my background as an embedded systems engineer. But what I couldn’t believe is that the kids loved it too! We were on vacation with 2 other families, each of which had 3 kids (like ours) of various ages. Very quickly, the 10 year old figured out how to beat Dr. Nim. Of course that made all the other kids want to try. Even the 4 year old learned to play. And then some of the other adults (even non-engineers) tried it for themselves, asking how it could possibly know how many marbles to take each turn so that it would (almost) always win. “How can pieces of plastic be a computer?” they asked. So we had a nice chat about where the term ‘computer’ comes from.

The thing that got me most excited was not that (modern) kids picked it up and were fascinated by it, nor that other adults were intrigued, but the thought that, in 1968 when it was available for sale to the general public, enough normal Americans bought it that it ended up in people’s game closets along with decks of cards and Monopoly. I suppose the thought of owning a ‘computer’ when such things were all the rage, was so new that spending a few dollars on a plastic mechanical game computer was something a lot of people did just out of curiosity.

And the instruction manual! I should have scanned it in. It has a mini-course in binary logic and boolean equations, ending with a discussion on how the game works, and how you can set it up in several different ways to play different games. And then it went on with “does this mean Dr. Nim can think?” and the open ended questions of machine thinking.

Too bad somebody doesn’t make something like that today . . . .  <grin>

After Brian wrote back to us, we found the manual for Dr. Nim through the Friends of Digi-Comp group. (Dr. Nim games frequently come up on eBay as well, if you’re interested in playing with one.)

The manual is truly incredible, with in-depth discussions about not just the mechanism of the game, but commentary on the effect of computing on culture in the long run. We’ll leave you with a thought from the manual, c. 1965:

The strides that man has made in the last 15 years in developing machines that extend and supplement his thinking are truly astounding. Who can say what enormous strides will take place in the next 15 to 30 years?

How Printed Circuit Boards are Designed (1960 Edition)

We found this gem in A Manual of Engineering Drawing for Students and Draftsmen, 9th Ed., by French & Vierck,1960, p. 487.

Printed Circuits allow miniaturization and the elimination of circuit errors—advantages that cannot be obtained by other methods. Once a pattern or suitable design is established, preparation of a black and white drawing can start. Scales for reduction, for example, 4 to 1, 3 to 1, or 2 to 1, are used. To insure sufficient bonding area of the metal laminate during soldering operations, lines should not be less than 1/32 inch in width when reduced. Line separation should never be closer than 1/32 inch on the final circuit. Figure 19.24 illustrates the drawing of printed circuits.

Introduction to Analog Mechanical Computers

Courtesy of the United States Navy comes this incredible introduction to analog mechanical computers.

The context for this is that massive, mechanical computers were used aboard US Navy ships ranging from destroyers to battleships, from about 1944-1969, as part of the “Fire Control” system.  This type of computer would take up to 25 continuously changing input variables in order to calculate the proper bearing and elevation for heavy caliber guns aboard the ship.  This calculation— to ensure that a projectile will land at the place where the target is going to be —is marvelously complex, taking into account variables such as wind speed and direction, relative velocity of the ship and target, and parallax between the different guns on the ship.  What’s truly remarkable is that it was all done with mechanical  mechanisms such as gear differentials, cams, and mechanical integrators.

This two-part training film, from 1953, introduces the basic mechanisms that made these computers work:

The video embedded above (41:53 total length) contains both films, one after the other.  (And, the YouTube link is here.)

Basic Mechanisms in Fire Control Computers, Part 1 discusses shafts, gears, cams, and differentials. Note that the first couple of minutes are not so much about the mechanisms, but more of an explanation— to the servicemen —of why they needed to learn about them.

Basic Mechanisms in Fire Control Computers, Part 2 discusses component solvers, integrators, and multipliers


If you enjoy these training films, you may also want to read through the little book entitled Ordnance Pamphlet 1140: Basic Fire Control Mechanisms, available here in PDF format, which covers much of the same ground.


Winner, Name that Ware May 2013

Mystery Ware May 2013 9

Congratulations to reader VAX-Dude for winning the Name that Ware contest for May 2013, by correctly identifying our mystery ware as a VAX 9000 series High Density Signal Carrier (HDSC).

Which might lead you to ask another perfectly reasonable question: What the heck is a High Density Signal Carrier? Continue reading Winner, Name that Ware May 2013

Name that Ware May 2013

Mystery Ware May 2013 7Mystery Ware May 2013 8

In cooperation with Bunnie Studios, the blog of renowned hardware hacker Bunnie Huang (of Hacking the xbox and Chumby fame), we’re pleased to present an unusual “ware” that we acquired from one of our local Silicon Valley electronics surplus dealers.

(If you’re unfamiliar with the game, “Name that Ware” is a regular contest on Bunnie’s blog, where the goal is to learn about reverse engineering by analyzing unusual— or common but seldom-seen —hardware.  You can read about the contest rules here, and you can see many pictures of past entries with this google image search, or even get a calendar featuring Name that Ware entries from prior years.)

In the detail photos that follow, we’ll show some close-up photos, and provide a little more physical description (without speculating too much as to the purpose of the different features).   Can you identify this piece of hardware?

Continue reading Name that Ware May 2013

Mystery components!

While picking out interesting vintage diodes at the electronics flea market, we came across a couple of components— possibly also diodes because of where we found them —of types that we have never seen before.  And we can’t resist a good mystery.



First, there’s this little two legged can, marked with 650, a black dot, and CO on one side. The other side (as you can see in the photo above this one), is marked T 1 and has black and red dots.


Secondly, a couple of things that look kind of like resistors:

They are very small, only about the size of 1/4 W resistors.  They are marked with a red capitol letter “P” and a set of four colored stripes. The “P” marking interrupts the three narrower bands in both cases.

Here’s a good look at the color bands: brown, violet, green, and then a broad yellow.  (We could be reading this wrong; is the broad stripe supposed to be read first?)

This one has brown, violet, green, and then broad violet.

So, what are they?  We don’t actually know, but if you do, or if you have a good guess, we’d love to hear it!

Interesting Diodes from the Electronics Flea Market

Diodes from the eFlea

We have written before about the the Silicon Valley Electronics Flea Market, one of our favorite places to go treasure hunting. At this weekend’s flea, we came across a cache of beautiful old diodes, including some in rather unusual packages.

Continue reading Interesting Diodes from the Electronics Flea Market