Want to read Slashdot from your mobile device? Point it at m.slashdot.org and keep reading!


Forgot your password?
DEAL: For $25 - Add A Second Phone Number To Your Smartphone for life! Use promo code SLASHDOT25. Also, Slashdot's Facebook page has a chat bot now. Message it for stories and more. Check out the new SourceForge HTML5 Internet speed test! ×

Comment homemade back then (Score 1) 857

My real first home computer, around 1976, was a perfboard with my design for an 1802 cpu, 1K of 1103 RAM chips, a video chip that did B&W blocks, a hex keyboard made of discrete switches with a two character hex display, and a bunch of support DIPS all hand wire-wrapped. There was no ROM, you had to hand load memory in hex and then start the CPU. Quickly I wrote a short loader that could load data from an audio cassette so only the loader would have to be keyed in. Earlier, around 1968, I got some kind of computer (I had never heard of the manufacturer) from a military surplus program for schools (incredible program - made a huge difference in my learning). It had a remote terminal that was like a fancy calculator connected with a thick cable to a box the size of a small refrigerator. Inside was a mass of panels and thick wire-wrapping connecting discrete transistors. Unfortunately it didn't work properly and in spite of many hours trying, I never did figure out how to fix it so it probably doesn't count although I learned a lot. Much later I got an Exidy Sorcerer with the S-100 expansion. I replaced the ROMs with custom ones I wrote and burned that included a real time interrupt so it could timeshare and multitask and load other ROM images (I could load ROMs to emulate a TRS-80, a Polymorphic 8813, and custom stuff). Later I added a Micropolis floppy drive and wrote a loader that read and compiled, starting with the first sector, forth-based text. I remember getting two floppy diskettes and wondering why I would ever need any more.

Comment Re:Time for a New Internet? (Score 1) 319

Mesh networks are great but the ones I've seen in use these days are not very scalable and require manual setups. There are a lot of issues that would have to be addressed not the least of which are the human use ones. Just remember that the point of the Internet was initially to connect all the little isolated networks that were out there using routers and it wasn't until around 2000 that that changed into the carrier model we have today.

Comment Re:Time for a New Internet? (Score 1) 319

Actually I'm a retired guy that lives out in an unincorporated area in Texas. I don't use Facebook. My social life is having friends visit but more than once a month is a busy month. My nearest neighbour is over a half mile away and the next nearest is a mile. The nearest store is 7 miles. The city is a 40 mile trip each way. Cable doesn't reach here and the telcos abandoned their copper lines years ago - I have a tree pulling down phone wires between poles outside but Verizon won't be bothered to come out to deal with for at least the last 4 years. Cell coverage was spotty at best - you had to go outside and find the sweet spot to call - until AT&T put in a tower just over a mile away about 2 years ago. The bare phone manages to cover that distance just fine. Wifi would need help, but having put in wireless broadband networks even an old PCMCIA wifi card can manage 15 miles reliably with a good antenna and some thought. It takes more to seed a rural area but even an old unmodified DLink wifi router can service an area of several square miles with the right antenna.

Comment Re:Time for a New Internet? (Score 1) 319

Sorry, just noticed that I wasn't logged in when I posted this. There was quite a bit of work done to implement this idea in the mid 1990's but a combination of a lack of ubiquitous hardware (cellphones were analog and none could run applications and routers cost thousands of dollars from Cisco) and intense offensive efforts on the part of telcos and some government agencies ultimately killed it and scuttled much of the work already done. Today's landscape and issues are different and perhaps it is time to implement this with fresh ideas.

Comment not so new, still needs magic to work (Score 1) 52

I've seen this idea proposed at least since the mid 1980's. The problem is the so-called "spatial light modulator" which doesn't exist beyond something a few millimetres on a side capable of not much more than making a fuzzy dot, and that only in the monochromatic light of the laser. The problems, to be practical, are being able to produce a plane larger than the area to be viewed that can change the phase of the source light precisely (with fractional wavelength accuracy) in real time at a density of greater than 25,000 pixels per linear inch and the bandwidth and computing horsepower to run it. No one has shown a way it can be done with today's technology for arbitrary images even though there has been much interesting work put into it over the decades. It's still out of reach for now. There is a way to address the issues and we can produce full colour displays that have both horizontal and vertical parallax as well as addressing the focus issue. Gabriel Lippmann, who won the Nobel prize in Physics in 1908 for his invention of a method of true spectral colour photography that were actually true full colour holograms which he produced a half a century before Dennis Gabor's work, also proposed a method of 3D imaging which became known as Integral Photography. Using an array of tiny lenses (NOT prisms as in lenticular displays) one can reconstruct wavefronts using a subtractive approach (subtracting phase components from discrete samples of white diffuse light) instead of the additive one used in modern holography. Numerous examples of varying quality exist going back many decades. Although impractical at the time, today it can be done. Back in the mid 1980's I received a patent (US patent 4,878,735) on using diffractive elements for the lens array and have a description of the technology in terms of it being an optical computing architecture (which I called "Integral MicroOptics") at http://www.eastjesus.net/tech/... (with some pictures if you are interested). Interestingly, the Patent office introduced a typo in the title of the patent calling "zone plates" "tone plates" and that has never been fixed! (Being a musician, I've always gotten a laugh out of that!)

Comment Re:Unfettered capitalism (Score 1) 639

According to John Deere you can't own a tractor here either, but they still expect you to pay them for it. Ever since the DMCA put the legal framework in place, large corporations have been in a frenzy stealing away ownership of the things we buy (or even already have) and converting private ownership to a licensing model. Tractors are just the latest but we've already seen it with cars, books, movies, music, software, and even housing, food, and water. The CEO of Nestle has been talking up the notion that his company should own the air and people should have to pay an ongoing fee to use it.

Comment It can be done well - with some effort (Score 1) 264

It took some time to get things set up and working well but with a low-latency kernel and Jackd as a core I now have a well-integrated audio system using Ardour as a multi-track recorder, Rosegarden with a USB midi interface for midi recording and editing, QSynth with the Fluidsynth GUI for a sample-based synth, Hydrogen for percussion, and sometimes other Jack-based applications as needed. Jack syncs everything up and makes it all work together in real time as an integrated system and Ardour records all the tracks and produces the final mix. I also use Audacity separately to record a track from an external mixer board or for processing a raw track or sometimes the final mix. I wish I could do as much with video on that system.

Comment Integral MicroOptics from the 1980's (Score 2) 65

Interesting work with a lot of unobvious possibilities. "Lensless" is a little misleading. Pinholes are just the center circle of a zone plate. Zone plates are lenses that work by diffraction instead of refraction. They look like a bulls-eye (see http://www.eastjesus.net/tech/... for a quick and simple primer). The diameter of the hole determines the focal length - hence too big OR too small leads to fuzzier images. The have a couple of big drawbacks - the focal length is a function of wavelength hence objects in the image have rainbow edges and the aperture of a focused pinhole is small (the f-stop). The effective f-stop can be increased at will by adding additional zones around the pinhole but zone plates that work by blocking areas can only achieve efficiencies of around 10%. That can be improved to around 90% or more by replacing the opaque zones with tapered phase-shifting zones. Back in the mid 1980's I worked with a similar technology using arrays of zone plates which we called Integral MicroOptics. We used arrays of micro-zone plates (and pinholes) to capture image data over large sheets (hence from many angles at once) and then reconstruct that data with full parallax in 3D and color, both stored and in real time and sometimes with some optical computing applied - all using passive devices! They were the equivalent of full color holograms using a subtractive technology instead of an additive one, hence no lasers were required and the more diffuse the light the better. It was amazing what could be done with thin flat sheets of plastic and printing but the technology of the day was too crude to get very far. Today much more could be achieved. If interested you can see the original paper from 1986 at http://www.eastjesus.net/tech/... (with updated graphics and a link to the original) and http://www.eastjesus.net/tech/... for some images created using the technology at that time.

Comment Re:vacuum tubes on a chip (Score 1) 109

Although there were internal documents, I don't believe any public papers were ever published on this project. The group's purpose was to identify technologies and get a head start on medical technologies useful in the 10 to 15 year time frame, and the company kept the work quiet. This project was about building a gas chromatograph on a chip to analyse blood gasses in real time non-invasively. In addition to etching the chromatograph tube as a channel, we also fabricated an on-chip thermal conductivity sensor and a "no moving parts" valve and compressor using fluidic logic also on the chip. We actually had the components working and were looking at building an integrated prototype that would self-calibrate and be able to do 10 samples/second of samples obtained through the skin. My "vacuum tube on a chip" experiment was something I tried using parts from those other experiments. The interesting thing we found was that heaters became unnecessary when the dimensions got very small, due to "surface electron clouds" or tunnelling we didn't have the time to find out. I do have an SEM picture of the sensor (which also worked as a heater) which I have posted at http://www.eastjesus.net/tech/... if you're interested in seeing it. We worked closely with Dr. Henry Guckel at the University of Wisconsin. He was profoundly knowledgeable and helpful on that project and I later worked with him again on a separate optical computing/imaging project later (more on that elsewhere in that web site). If you haven't already, you might want to look into some of his other work which was published. Best of luck and let me know if I can be of more assistance.

Comment Re:Not the first, but more useful for today (Score 1) 288

Not an air raid siren, for sure, but you'd be surprised at how loud that little speaker could be driven full bore rail-to-rail with a square wave at resonance with the case. Even when in an enclosed office on the fourth floor it could be heard inside offices in the adjacent office building.

Comment Never works quite right (Score 1) 164

There is a story (I've heard it from several sources over the years but I won't vouch for its veracity) about an early translation program that the US military commissioned, sometime in the sixties I think, that illustrates some of the problems. This program was meant to translate English to Russian and vice versa. At the demo all the higher-ups were there, typically not having a clue about the complexity or pitfalls of the task. One of them suggested that the phrase "The spirit is willing but the flesh is weak" be entered, translated into Russian, and the resulting phrase translated back to English. The technician did what he was told and I have visions of cabinet-sized tape drives spinning furiously for awhile until the processing was complete. Finally, the printer spat out the result. I hear the technician dropped the paper and ran away. When someone picked up the printout it said "The vodka is strong but the meat is rotten!"

Comment Not the first, but more useful for today (Score 5, Interesting) 288

Reminds me of something I wrote back around 1981. Working with the early IBM PC at the machine code level several flaws surfaced and for fun I packaged them all together in the boot sector of a 5 1/4" floppy which we put in a "break glass" box and put on the wall (There were no hard drives yet, the XT wasn't out yet). If you placed the floppy in the boot drive it would destroy the hardware in a few seconds. First, there was a bit on the original IBM display adapter (mono text only) which would lock the horizontal sweep on the standard IBM monitor forcing the horizontal output power transistor to overheat and burn out. You would see the display image collapse while the monitor would squeal while smoke (literally!) would come out the sides and back, and die with a $200 repair to fix it. Second, there were no stops on the head movement on those original floppy drives - with the right loop they would step out until the heads fell off inside the case with a pair of clunks if you had a 2 drive system. (Not a difficult repair, but you had to know what your were doing and get into the floppy drives themselves to fix it.) Finally, the speaker ran off of a shift register which could be loaded with a really nasty PWM sound and set to free run. With interrupts disabled and the CPU halted, the machine sat there smoking with a very loud nerve-rattling siren, completely dead and unable to boot. It would require major physical repairs to get it working again. The monitor would stink for weeks afterwards.

Comment Strong opposition to critical thinking skills also (Score 2) 553

There are those who are actively working at making sure those skills are NOT taught: "We oppose the teaching of Higher Order Thinking Skills ... critical thinking skills and similar programs [which] have the purpose of challenging the student's fixed beliefs and undermining parental authority." --2012 STATE [Texas] REPUBLICAN PARTY PLATFORM. Unfortunately, these same people also control the largest school system in the country which determines the course materials used by many other school systems.

Slashdot Top Deals

"All we are given is possibilities -- to make ourselves one thing or another." -- Ortega y Gasset