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TEM Logo The Embedded Muse
Issue Number 332, July 17, 2017
Copyright 2017 The Ganssle Group

Editor: Jack Ganssle, jack@ganssle.com

   Jack Ganssle, Editor of The Embedded Muse

You may redistribute this newsletter for non-commercial purposes. For commercial use contact info@ganssle.com.

Contents
Editor's Notes

VDC is conducting their annual survey of the embedded market. The link is here, and "As a token of our appreciation for your time and input, if you qualify for and complete this survey, which takes on average 20-40 minutes, we will offer you a choice of a $40 Amazon.com e-gift card or a $40 donation to Doctors Without Borders to support medical relief efforts." I'll publish any interesting results in an upcoming Muse.

I'm now on Twitter.

Quotes and Thoughts

"Good judgment comes from experience, and experience comes from bad judgment." - Fred Brooks

Tools and Tips

Please submit clever ideas or thoughts about tools, techniques and resources you love or hate. Here are the tool reviews submitted in the past.

Miro Samek has a really cool programmer's calculator. See this.

The inventor of the TMS9900, which he describes as "a dog of a chip," reminisces about its invention here.

"Big data" is the rage today and I know data scientists who are using it for some fascinating, and some silly, applications. A lot of this work is being done on GPUs, but I've often wondered if FPGAs would make more sense, especially since these applications are not cost-sensitive. Here's an interesting paper about the idea.

Mike Perkins wrote: "Martin Thompson's comments reminded me that embedded is starting to use blockchain. Some of your readers might enjoy this excellent tutorial video and the accompanying fun sandbox.  https://anders.com/blockchain/

When not traveling, I dedicate some time every Monday morning to reading electronics/software web sites to keep up with the field. One site I find invaluable (though it's a monthly publication) is Analog Device's Analog Dialogue. Sure, they push their products, but there's always interesting articles about the art of designing analog electronics.

A Vintage Scope

Tektronix introduced their first product, the model 511 oscilloscope in 1947 (some sources claim 1946), a whopping 70 years ago. Not just a knock-off of some standard scope design like the ones complacent Dumont were marketing, the 511 was the first scope with triggered sweep. This product launched both Tek and the modern oscilloscope.

We take triggering for granted today, but not so long ago inexpensive scopes didn't have it. In the 60s my dad took a home-ed electronics class from Devry in which he assembled a combination scope/VTVM (Vacuum Tube VoltMeter - the "Fluke" of the era), which he passed on to me while I was in 8th grade. Untriggered, it simply kept sweeping the beam, synchronized to nothing. A "sync" knob varied the time base to stabilize (somewhat) the display, but that meant it was tough or impossible to measure time with much accuracy.

Though sold as a portable unit, the 511 weighed in at a backbreaking 50 pounds. It offered 10 MHz bandwidth, though "MHz" wasn't used in this country then so the data sheet specified bandwidth in "MC" or "mc" for megacycles. Fastest sweep rate was a blinding .1 usec/division.

The design presaged the modern oscilloscope in a way; in the 50s Tek's wildly-popular 500 series, and then later the 7000 series in the 60s, sported a modular design where the scope had one or more plug-in modules. Big holes in the instruments' chassis were filled with vertical and/or horizontal units of differing specifications. That fad died out; today, as in 1947, scopes generally don't have plug-ins.

The unit cost $795 in 1947 dollars, or about $9000 at today's rates. That seems a bargain when you consider that it was a high-performance, highly-innovative product that had little direct competition. Today a high-end unit can price out at more than $100k.

I can't find a manual for the 511, but one for its immediate successor, the 511A - with schematics! - is here: http://bama.edebris.com/manuals/tek/511aearly/ . A rough count identifies about 33 vacuum tubes, of which only two are twin triodes. 13 of those are in the power supply, so the scope's "smarts" use only about 22 active elements! In modern terms, 22 transistors. No multicore. No DSP.

Those tube engineers sure were great designers.

A decade later Tek's extremely popular 545 had a mere 102 tubes, yet offered so much performance that that series was still in use 30 years later.

The company sold $27K worth of 511's in 1947, growing by an order of magnitude the following year. Today they're a billion dollar company. There's little loyalty to companies anymore, but many old-timers still fondly recall their experiences with Tek's products. Me, I worked with the 7000 series in the 70s, instruments that were just a delight to use. Small illuminated interlocked buttons and selector switches with perfect detents were magnificently fitted to human hands. I had an ancient 545 that never failed - I never even changed a tube. But around 1990 it had been sitting neglected for a long time. No one wanted it and I junked the thing. Now it would be a museum piece.

Today,Siglent, Rigol, Owon and many other Chinese companies produce excellent low-priced scopes. I have a Siglent SDS 1102CML which retails for $300 on Amazon; its specs make Tek's old 511 seem laughable. Most of us need an instrument with better specs, but these companies sell higher-end products that give some of the products from the older, entrenched vendors a run for the money. And, Tek and Keysight do have very low cost scopes that are orders of magnitude better than anything from the 1940s. Or even the 1980s.

What was your experience with early scopes?

On XML and JSON

Jay Atkinson had the final say on XML and JSON:

I read your recent newsletter talking about JSON vs XML which I found interesting.  I'm also not a big fan of XML, because I find it too verbose for how it's being misused.   From my understanding of XML, it was never designed to be a serialization format nor a configuration file format.  It's designed for documentation markup.

I have found JSON a much better alternative to XML, because it's concise and is also much like writing data structures.  So it makes a better serialization format than XML, and that is it's original design goal.   However, I find it lacking as a configuration file format mainly because it does not support comments!  Comments are immensely useful in a configuration file, because sometimes you need to leave information behind for maintainers or you need to test different configurations between executions of a program by commenting out chunks of text.

Enter YAML or "YAML Ain't Markup Language" - http://www.yaml.org/.  As of the latest standard, YAML has been made more compatible with JSON.  It supports comments.  It is very concise just like JSON... and now compatible.  It can be used for serialization.  There are many language bindings for it such as C & C++, Python, Ruby, Java, etc!  For the readers that like JSON, I think it's worth their time to check it out.  It may be a better solution for some problems they are trying to solve such as configuration files.
This Week's Cool Product

Power management is increasingly important in embedded applications, and some amazing products can help. Old-timers remember using 2N3055s in what would today be considered enormous TO-3 cases as pass transistors in extremely inefficient linear regulators. The new LTC7124 step-down regulator from Linear Technology is sort of mind-blowing. Though it's in a 3x5 mm QFN package it will source 3.5 amps from each of two channels (nope, no pass transistor needed) with a Vout of up to 99% of Vin. And, it can operate in a spread-spectrum mode to reduce EMI. Four bucks in 1000 lots.

Note: This section is about something I personally find cool, interesting or important and want to pass along to readers. It is not influenced by vendors.

Jobs!

Let me know if you’re hiring embedded engineers. No recruiters please, and I reserve the right to edit ads to fit the format and intent of this newsletter. Please keep it to 100 words. There is no charge for a job ad.

Joke For The Week

Note: These jokes are archived at www.ganssle.com/jokes.htm.

 

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