11 NOR Gate Ring Oscillator

More Christmas lights.  My day job is doing the plant shutdown thing through Jan. 2 so I am planning to get 36 gates onto this board and route a 3 bit up counter.  At least something with two clocked D Latches and logic.

What The Heck Is That Thing?

Well, get a picture of me standing next to it. . .

How handy is that?  I can post a YouTube video directly to a blog post.  The blurriness of the opening shot appeals to me in some "what the heck is that thing?" fashion.  This is the first video I shot and posted of the NOR gates in action.  In this instance as a simple ring oscillator.

NOR Gates

Getting Started On The Large(ish) Array

Started to build the latest iteration which should allow for 51 NOR circuits.  Maybe less, no point in crowding parts and making it hard to solder.

Here I am moving along to make sure I can fit three rows (two down one to go) before I start building across the protoboard.  The 110 VAC thing is a bit worrisome but I am disciplined about when to power up and test.  The complete assembly will be properly cased to prevent any inadvertent contact with dangerous voltages.

I think I should have enough NOR gates to do a 3 bit up counter.  Here is my latest least number of NOR gates edge triggered D Latch:

The lower circuit is the actual D latch and the upper circuit is "pulse shaper" which conditions the clock to be of short duration.  The pulse shaper should only be required for every four latches which should save on NOR gates.  I am thinking a 3 bit up counter would take about 35 NOR gates.  I will draw one up in the next few days as build and test circuits on the protoboard.  Maybe have something running this weekend.  I should do a video of the edge triggered D latch at least by this weekend.

Cellular Automata Or Something Else?

I put together a "ring" of D Flip Flops with the data input set by XORing nearest neighbors, which seems to me to meet a version of the "Conway's Game of Life" rules:
1. Too many neighbors = off.  In this instance too many neighbors is 2, one on each side
2. No neighbors = off. I this instance no neighbors is no one on either side.
3. Just right = on. One neighbor on either side.

Below is a screen shot of the circuit, including a simple preset and the results of manually clocking through 7 states.  It appears to begin repeating at state 4.

If you are interested in designing a simulating digital logic I highly recommend "Cedar Logic Simulator."
You can get it here for free:
http://sourceforge.net/projects/cedarlogic/

The next step is to do the same thing but with all NOR gates.

Planning for Publication

1. Read "Incredibly Useful Advice for Physics Students Writing a Senior Thesis."  This is a perfect application for the netbook.  Kinda the whole reason you bought it.
2. Use the blog to collect your thoughts and codify your effort.  Conceive, Believe, Achieve are more than just words.  It has worked before and it will work again.  Particularly for  a goal that lends itself to being split into "doable chunks."
3. Collect references for the bibliography and comment on them.
4. Construct an outline and or table of contents for (Working Title) "Cellular Automata Using Optically Routed NOR Gates."
     a. Purpose - Demonstrate a technology for implementing sequential and combinatorial logic circuits from novel components that are comprehensible to an early engineering education audience.  Including how to construct a simulation program.
     b. Survey of previous work by others
     c. My work to present date
     d. How it works in hardware.
     e. Example circuits leading to and including CA
     f. Utilizing MIT open course resources to suggest a curriculum for a hands on digital logic and elementary computer science class for pre college students.
     g. Conclusions
     h. Acknowledgments
     i.  Bibliography
5. Overcome reticence in taking next steps.  The secret to edge triggering sequential circuits was in your previous research from 1995.  What you did and can do takes precedence over what you read and what people tell you is possible.  (I am generalizing something that happened to me in second person voice, hmmmmm).  Oh, well.
6. Query the SPIE conference representatives?  I think that was how I got started last time.  A mentor or collaborator would be nice.
7. Build the the 51 NOR gate board.
8. Simulate 1D CA in Cedar.
9. Work on simulator in Scheme.

Piano in Paris

Both a disappointment and an inspiration at the same time.  Ahh, dichotomy where would I be without you splitting me in two or three? (trichotomy?  Sure enough it has a Wikipedia entry. . .).  I met some wonderful musicians at Le Chat Noir and a restaurant  in Montmartre but was not able to secure playing time for myself.

 Musée de Montmartre which I thought would be a veritable fountain of Erik Satie information has almost no mention of him. . .hmmmm.  I have a theory it has to do with his love affair with Suzanne Valadon and her (afterwards the affair) husband's ownership of the the building that now houses Musée de Montmartre but that could just be the jet lag talking. . .

At any rate I think there is a interdisciplinary mail art project in there somewhere.  We'll see.

Return From Paris

Went to Paris on sort of whim and because off season is like 1/3 the normal price. The history of technology has been an inspiration to me since my grade school days and Lavoisier was calling me.  I was able on the trip's long flights and occasional sleepless nights to figure out how to make an edge triggered D flip flop from NOR gates only which is imperative for this project which does not allow capacitive coupling.

Also started accessing the SICP (Structure and Interpretation of Computer Programs) lectures and learning resources here:

http://ocw.mit.edu/courses/electrical-engineering-and-computer-science/6-001-structure-and-interpretation-of-computer-programs-spring-2005/index.htm

If you have ever wondered "how" to program, rather than apply example code snippets and hack. This might be just the ticket.  It certainly has opened my eyes.  The video lectures are engaging and inspiring in that they specifically address using imagination as the starting point to programming.  Of course rigor follows but rigor informed by "wishful thinking."  Good stuff!

The original motivation (and continuing) to study SICP is to design a NOR gate only digital simulation environment to complement the hardware.  SICP addresses how to "build" a digital simulator as part of the course.  I think this is just so handy dandy I can hardly stand it. Particularly since it is presented in such a comprehensible fashion.

I was able to watch several lectures during the flights and work through some of the examples on constructors and selectors.  I have learned about these concepts previously in computer science courses but was so intent on "getting done and getting a grade" that I didn't appreciate their power.  Talking to the senior software engineers at work (I am a hardware dude) we now have a much richer and constructive conversation about "how" software is constructed by determining data structures first and letting the functions almost write themselves.

I should go to Paris more often.

If you have a mind to go see Foucault's Pendulum at the

Musée des arts et métiers it may just rock your world.