标签: computer

My first job fresh from college was testing and debugging control loading systems on flight simulators for 747 and the "new" 767 airliners. In the late 1970s, the control loop that simulated the feel of the primary flight surfaces, and had to respond instantaneously to pilot inputs, was purely analogue; the digital portion consisted of a 32-bit Gould SEL "super minicomputer" with schottky TTL and a screamingly-fast 6.67 MHz system clock; it merely provided voltage inputs via DACs into an op amp summing junction which represented slowly-changing parameters such as airspeed and pitch angle.   "Op Amp", of course, is short for "Operational Amplifier", first developed to perform mathematical operations in analogue computing. Forget about FFTs, DSPs, and all that nonsense: back in the mid-70s (when analogue giants walked the earth and the Intel 4004 was barely out of diapers) there was an analogue IC for just about everything – multiplication and division, log and antilog operations, RMS-DC conversion, you name it.   With the later rise of the Dark Side , of course, many of those old analogue components, as well as the companies that gave them life, have breathed their last.   At least some of those functions survive, either as standalone parts or (sigh) as microcontroller functional blocks. And the real world, thankfully, remains stubbornly analogue, which means that most of the truly interesting "digital" problems are really analogue problems – grounding, crosstalk, race conditions, noise, EMC, etc.   We humans are products of the real world, too. Are we analogue or digital?   The information that makes up a unique human being is mostly to be found in two places, in our genes and in our brains. The information in genes can be considered digital, coded in the four-level alphabet of DNA. Although the human brain is often referred to as an analogue computer, and is often modeled by analogue integrated circuits, the reality is more nuanced. In a fascinating discussion on this subject, computational neuroscientist Paul King states that information in the brain is represented in terms of statistical approximations and estimations rather than exact values. The brain is also non-deterministic and cannot replay instruction sequences with error-free precision; those are analogue features.   Figure 1 Figure 1: Analog, digital, and neuron spiking signals (source: Quora )   On the other hand, the signals sent around the brain are "either-or" states that are similar to binary. A neuron fires or it does not, so in that sense, the brain is computing using binary signals.   The precise mechanism of memory formation and retention, though, remains a mystery and may also have both analogue and digital components.   Is life itself analogue or digital? Freeman Dyson, the world-renowned mathematical physicist who helped found quantum electrodynamics, writes about a long-running discussion with two colleagues as to whether life could survive for ever in a cold expanding universe . Their consensus is that life cannot survive forever if life is digital, but life may survive for ever if it's analog.   What of my original topic - analogue vs digital computation? In a book published in 1989, Marian Pour-El and Ian Richards, two mathematicians at the University of Minnesota, proved in a mathematically precise way that analogue computers are more powerful than digital computers. They give examples of numbers that are proved to be non-computable with digital computers but are computable with a simple kind of analogue computer.   Consider a classical electromagnetic field obeying Maxwell's equations: Pour-El and Richards show that the field can be focused on a point in such a way that the strength of the field at that point is not computable by any digital computer, but it can be measured by a simple analogue device.   The book is available for free download . Digital engineers, knock yourself out.   Meanwhile, analogue rules supreme. Which, of course, we analog engineers knew all along.   Now, about that raise.....   Paul Pickering

Not typical of me, I was not wearing my happy face several days ago, nor did I perform a single happy dance. The reason for this sad state of affairs started when I arrived at my office at the crack of dawn and powered up the main tower computer that drives the three 28-inch monitors forming my desktop.   Everything seemed to be OK at first. The various applications (Outlook, Firefox, Excel, Word, Visio, Notepad, etc.) appeared to open and run as expected while I was setting up my desktop the way I like it. As soon as I tried to do anything with any of these applications, however, that program immediately locked up. If I subsequently tried to use the ctrl-alt-delete key combination to access the task manager, the entire system locked up and then all three screens went black. Strange to relate, the only thing that continued to work was the lonely cursor associated with my mouse, and there’s not much you can do with a cursor on an otherwise blank screen.   I tried re-booting the machine several times to no avail. There were probably other things I could have tried, but I’d pretty much reached the end of the line. To be honest, this computer has been getting flakier and flakier recently, and I’ve been expecting this day to come for a few months now. We’ve run antivirus and anti-malware tools, and we’ve tried swapping memory sticks and running low-level diagnostic and intensive burn-in tests, but at the end of the day there’s only so much you can do.     I must admit to feeling a tad forlorn. This machine has been a true and faithful companion for several years now. It was actually a refurbished unit I purchased off eBay for around $350. The graphics card was a beast that could drive two high-resolution monitors. I soon discovered that a new card of the same type would have cost me around $450 (eek!), but then I tracked down a refurbished version on eBay for something like $30. Since that time, I’ve been working the poor little scamp into the ground, pounding away on my keyboard, orchestrating things with my mouse, creating blogs, editing images, and doing suchlike from dawn till dusk, day-in and day-out. I know how frazzled I feel, so I’m not surprised that my tower computer eventually gave up the ghost and shrugged off this mortal coil.   The thing is that I can’t survive without my big-boy computer. I can struggle along on my notepads – as I must do when I’m travelling -- but I can generate only a fraction of the throughput I manage on my primary setup. If you couple this with the fact that I am a man of little patience, who is not prepared to wait several days to obtain a new machine, you can see we have a problem.   Of course one can find computers at places like Best-Buy and Walmart, but these are pretty much generic boxes targeted at the masses. These machines may be OK for home use, but I haven’t had much luck over the years using them in a grueling professional environment.   Fortunately, I have a chum called Daniel Imsand who works at a local company called GigaParts . This is an interesting organization with two faces to it. On one hand it is the largest independent ham radio distributor in the USA (and possibly in the world). On the other it builds and sells kick-ass PCs. The GigaParts Zero Systems brand is divided into three categories: Zero Home PCs, Zero Gaming PCs, and Zero Workstations.   Daniel is the product manager for all of GigaParts' Zero Systems. He is tasked with creating custom configurations with great pricing boasting the most reliable and stable components. As Daniel told me, GigaParts includes parts and labor warranty -- three years for both on the machine I ended up purchasing from them. But, given a choice, it prefers not to have to do any warranty work, so the company designs and builds its machines in such a way that they keep going, and going, and …   A lot of GigaParts' computer business involves creating custom value-added systems that it builds to order. (Apparently it does a roaring trade in professional-grade flight simulators.) But it also offers prebuilt, off-the-shelf systems sufficient to make even a grizzled old engineer like me squeal with delight. (It was not a pretty sound.)   I called Daniel on the phone. Based on his recommendation, I settled on a Zero Pro Z7 Plus machine. This little beauty boasts a quad-core Intel Core i7-4790 processor running at 3.6 GHz (be still, my beating heart). This is augmented by 16GB of DDR3-1600 RAM, an enterprise-grade Intel Pro 2500 Series 240GB SSD (solid state drive), an nVidia Quadro K620 Workstation GPU, SuperSpeed USB 3.0, and more bells and whistles than you could swing a stick at.   One thing I really like is that the company offers this machine with Microsoft Windows 7 Professional 64-Bit. (I have little regard for Windows 8 on my office machines.) As soon as I got off the phone with Daniel, I leapt into my truck and raced over to the GigaParts building. By the time I arrived, about 20 minutes later, my new machine, along with a bunch of HDMI cables and appropriate connectors, was sitting on the counter waiting for me. After undergoing a few formalities, like paying for the little scamp (thank goodness for credit cards, is all I can say), I zipped back to my office and commenced connecting everything together.     To be honest, after spending the past several months trying to keep my old machine gasping along, I've grown a little tired of crawling around under my desk, replacing parts and messing around with cables. Thus, I decided to locate this new machine on the top of my desk behind the monitors, as shown in the picture above.   I then spent the rest of the day downloading and/or reloading my various applications, like Microsoft Office, Microsoft Visio, Paint.net, and so forth. I also downloaded Mozilla Firefox, which is my preferred Web browser, and I made sure that Google.com is the default search engine that appears on the screen when I launch that browser.   Then the next day -- a brand spanking new day. Once again I'm wearing my happy face and all is now well in the Land of Max, where the colors are brighter, the butterflies are bigger, the birds sing sweeter, and the beer is plentiful and cold. I just powered up "the beast." OMG, this machine is so fast ! The password box appears on the center screen only a second or so after you've pressed the soft power button. As soon as you enter the password all three screens immediately spring to life. When I launch an application like Word or Excel, it appears on my screen in a flash. It's so fast, in fact, that I get the impression the program has launched before I've finished double-clicking its icon on my desktop.   Having said all this, I have run into one slight problem. I think this came about when I downloaded a new copy of the free PDFCreator utility that I've been using for years, but I can’t say for sure. All I know is that now, when I launch Firefox, I'm presented with the Google search engine on the initial tab, which is what I want. But if I subsequently click the '+' icon to open up a new tab, that tab appears with the loathsome Bing search engine flaunting itself in all its horrible glory. I've tried playing with the "options" settings, but for the life of me I can’t work out how to stop this from happening.   Are you aware of any problems associated with downloading PDFCreator, and do you have any ideas as to how I can banish the despicable Bing search engine back to the nether regions from whence it came?

It was the early 1970s when I was sent overseas with three impressively sized racks of equipment controlled by a Honeywell H316 computer. Along with them came the orders to install the system and get it running. My adventure began when my boss sent me to a local one-week Honeywell computer course on machine language. That single course was the only training I received on this new system. Apparently, I couldn't be spared for the longer hardware courses, though my boss did allow a technician (who was going to the same location as the equipment) to attend. I only had to install the computer system, train everyone how to use it, and leave. That was the plan. The peripheral devices included a paper-tape reader, teletype terminal, large reel-to-reel digital magnetic tape drive, high-speed printer, data interface, and a huge hard disc. The hard disc was about a foot high and completely sealed inside a cylindrical enclosure that was pressurized with an included nitrogen bottle and pressure regulator. As I later discovered, it was fortunate that all the hard disc electronics boards were mounted outside the pressurized enclosure. "This is not me (or the system I installed), but it is a similar picture that I found on the Internet."—Steven Karty This was back in the olden days before BIOS ROMs told the computer what to do after being turned on. So I had to "fat-finger" in around 30 16bit words of instruction, which told the computer how to read the punched paper-tape reader output. Then I had to load an ASCII punched paper-tape into the paper-tape reader, which told the computer how to read the magnetic tape drive's output. Then I had to make sure that the large magnetic tape reels, which contained the computer program, were mounted and rewound to their beginning. Then, when I had everything ready, I would simply hit the start button, the computer would read the punched paper-tape, the magnetic tape reels would spin, and the whole system would start. This initialisation procedure had to be repeated each time the system was powered on. Before the system could be shipped, it had to be packed. Before it could be packed, everything heavy had to be removed from the racks and packaged separately. Although other people did the packing and crating, I first had to disconnect and remove the equipment from the racks and make sure that I would remember how to reinstall it. Everything went smoothly—at first. The equipment, the technician, and I arrived intact at our destination. I reinstalled and reconnected all the equipment, cued everything up, and hit start. Then things got rough. The paper-tape reader ran, but the magnetic tape reels refused to budge. Most of the hardware peripheral interfaces were not only unique and custom-designed, but also poorly documented. I called the technician over and asked for his help. We single-stepped through the instructions where the computer was stuck and figured out that the computer was waiting for the hard disc interface. The computer could not go onto the next step and tell the magnetic tape reels to spin until this disc interface was ready. After using a Tektronix scope to trace through the disc interface, we concluded that the interface was waiting for a signal from the hard disc. The technician then abandoned me, saying he had been trained only on the interface and not on the hard disc. As he slipped out, he mumbled that the "origin" signal from the hard disc seemed to be missing. I realised that I would be blamed if I couldn't fix the system. That I hadn't been allowed to attend any hardware courses was irrelevant. Unfortunately, there were no replacement boards for the hard disc. Fortunately, the system documentation included schematic diagrams of the hard disc electronics boards. Deserted by the technician and feeling very lonely, I picked up the scope probes and began tracing through every circuit where I thought the origin signal was supposed to go. I finally found the origin signal at the input to a potted delay line. But I didn't see anything at the delay line's output. In desperation, I decided to solder a jumper wire around the delay line. When I then repeated the initialisation procedure, everything worked perfectly! The manufacturer of the hard disc later said the design had enough margin so it did not need a delay line, but it sent a replacement anyway. In the end, all it took was just a piece of wire to fix this computer system. But I never would have found the problem, and thus its solution, without an oscilloscope. And I would have lost interest long before finding the problem if using a Tektronix scope were not so much fun. I met another technician (who had spent two years where I installed the equipment) before I left on this trip, and asked him for any hints about the site. He said it was nice and safe, so I wouldn't have any problems. That was only partly true, because I had stomach problems the entire time. I saw him after I returned and asked if he ever had any gastrointestinal issues. He said that while he always felt fine, his wife suffered from the same problem as I had described to him in such graphical detail. When I asked him what might account for the difference, he said his wife drank the local water but he drank nothing but beer. I didn't bother asking him why he forgot to tell me that before I left. But I still wonder if he brushed his teeth with beer. I still get a kick out of using Tektronix scopes because their triggered sweep circuits always work perfectly—which is why I finally bought my own. But it's an old analogue scope with a CRT. The new Tektronix scopes with their digital displays are way more fun. Steven Karty built an oscilloscope from an EICO kit in the mid-1950s when he was 10 years old. He started working in radio and TV repair shops at 13, became an amateur radio operator at 14. He has used Tektronix scopes almost exclusively for the last 48 years, and he has BSEE. He submitted this article as part of Frankenstein's Fix, a design contest hosted by EE Times (US).  

As a young lad at university circa the late 1970s, I used to read electronics hobbyist magazines and drool over adverts for rudimentary single-board computers with 1K ROM, 1K RAM, a hexadecimal keypad, and a couple of 7-segment LED displays. I cannot tell you how I lusted after one of those little beauties, but they were way out of my price range as a student. I dreamed of one day owning my own computer (although I didn't think it likely). At that time, I had no idea that one day I would be walking around with enough computing power strapped to my back to control a spaceship. A reader recently wrote: I think that you should start a contest to see who takes the backpack with the largest variety of stuff (electronic equipment, test tools, adapters, etc.) through security. Contestants should submit pictures detailing everything they have in their bag. On average I have at least two flights a month (most of them internationally) and I carry a civilian version of pack that Camelbak made for the US military loaded with about 15Kg of stuff. This started me thinking, resulting in the column you are now reading. I'll show you mine if you show me yours. Please share descriptions of the contents of your backpack. In fact, I actually wander around carrying both a backpack and a messenger bag, as illustrated below. These go with me everywhere. I bring them into work each morning and take them home again each night, and they form my carry-on luggage when I'm traveling.   I started using the Swiss Gear IBEX Computer Backpack (on the left-hand side of the image) back in 2010 following an unfortunate accident with a cheap-and-cheerful pack I had been using. I store my main notepad computer in my backpack. The problem is that this is a tad large to squeeze under a seat when you are traveling on a plane. What I want to do is immediately slide it into an overhead locker and take my seat. Thus I also carry my leather messenger back from Saddleback Leather . In addition to holding my reserve notebook, this also carries my traveling essentials, such as my iPad and noise-cancelling headphones, etc. OK, now let's delve into these little rascals to see what they contain. As I say, I carry them around with me every day—the various items are always stored in the same locations. "A place for everything, and everything in its place," as they say.     Before each trip, I completely empty both bags and then repack them to make sure everything is exactly as it should be. I guess this is now part of my traveling ritual, but there's also the fact that "I R an Engineer!" The main thing is that once I've repacked everything, I have renewed confidence to face the ordeals of the coming trip. A brief summary of the various items is as follows: 1. My main notepad computer. When I'm working in my office, I predominantly use a tower computer with three 28-inch monitors, but I also use this notepad—this is the one that sits on top of my treadmill desk during the day. 2. The power supply for the main notepad computer. 3. The mouse I use with the main notebook computer. 4. A wireless mouse-type thing that acts as a laser pointing device and allows me to control PowerPoint presentations while giving talks. 5. My Flip video camera. 6. This is actually my iPhone, which is usually in my pocket. In this picture it's standing in for my 16-mexapixel digital camera that I'm using to take the above picture. 7. The charger for the digital camera. 8. The headset that accompanies the Dragon speech recognition software that's loaded on my main notepad (this software is very useful when I'm walking/working on the desk treadmill in my office). 9. A power extension cable with three sockets on the end; I find this to be very handy when I'm on a long layover in an airport and there are limited power sockets available. 10. A bunch of USB flash drives. I remember when the first ones came out—32MB (yes, megabytes) and I could barely afford one; now they come in multi-gigabytes and people give them away. Note in particular the tubular device (second from the left); this is a 32GB stick in a container that's waterproof to a depth far greater than I could hope to survive. 11. A collection of batteries for various appliances. 12. The charger for my iPad and iPhone. 13. A paper notepad (I also carry a bunch of pens, not shown here) and a couple of unread graphic novels I carry in case of an emergency. 14. My backup notepad computer. This is the one that sits on the docking station on my desk during the day. Traveling with two notepad computers may seem a little excessive, but wherever I am I spend all day working on the Internet, and if I have only one computer that crashes and burns, then I'm dead in the water (as it were). 15. The power supply for my backup notepad computer. 16. The mouse I use with the backup notepad computer. 17. My trusty iPad (yes, I couldn't resist, the leather cover is also from Saddleback Leather). 18. My Sony digital noise-cancelling headphones (they make flying bearable). 19. An incredible little Bluetooth loudspeaker I use with my iPad. This was a gift from Microsemi at the recent Design West 2013, and I have to say that I am blown away by the quality of the sound. 20. Another paper notepad and some more unread graphic novels I carry in case of an emergency. One thing that's not shown in the image above is the fact that I invariably have a couple of paperback books on me when I'm traveling (plus several more in my main suitcase). Now, you may think this is silly, but for the longest time I used to stuff all of the cables in one pouch of my main backpack. The result was that I spent countless hours untangling wires. Then, one day a couple of years ago, it struck me to start putting each charger, mouse, cable, etc., in a separate plastic food bag. I can't believe I didn't think of this sooner. Now, it's much easier to find what I'm looking for, I never have any tangles, and life is just better all around. Arrgggh! I just realised that I omitted a couple of items—my Nixie tube wrist watch and my Geiger counter as shown below:   The reason I forgot these is that I don't carry them around with me everywhere—only when I'm traveling. The rest of the time they sit on the bookshelves in my office. The Geiger counter (a little beauty from Mazur Instruments ) is merrily chirping away to itself behind me as I pen these words. So there we are. Now you know what's in my backpack. What about you? Do you travel much lighter than me, or do you have so much "stuff" that you put me to shame? Please let me know by posting a comment below.

Last month, I read this fascinating story in an issue of Physics Today about "listening" to your data—literally, see " Shhhh. Listen to the data ." The article showed how making real-world data audible allows the ear and brain to sense patterns, extract features, and find occurrences which might otherwise not be found by conventional data-analysis packages. This may seem a counterintuitive throwback to those quaint, ancient methods in our software-intensive world, but reality is that the brain can extract things that even our most impressive computers and algorithms can't, or which require significant computing power to achieve. Also, the brain is good at dealing with the unexpected, while even the best data-analysis package can only find what it has been "programmed" to expect. A few years ago, I spoke to some people doing software for the DARPA autonomous-vehicle road race, and asked them about the biggest challenges they faced. The answer was pretty quick and unambiguous: having the vehicle "see" where the actual road was, and not be misled by trees, signs, fences, obstacles, distractions, road irregularities, and the almost countless other realities of what the vehicle's cameras could see. Many lines of code and corresponding MIPS were dedicated to image recognition and feature extraction, they added. The irony is that seeing and then knowing where the road is turns out to be pretty easy for almost anyone, even those with poor actual driving skills. Yet the brain is not executing millions of lines of code, nor doing MFLOPS of processing to figure it out. Whether using audible, visual, or other senses, the brain is amazingly good at determining patterns and anomalies. And don't kid yourself: we have almost no idea how the brain does this, despite what the neuroresearchers would like you to think. Experienced engineers use all their senses when designing, assessing what's going on, and finding out what's not going as expected. Good design and debug is a combination of formal tools and also the human ones: sight, sound, feel, and yes, smell. The best debugging methods I have seen and used are also the oldest: look, listen, expect the unexpected, and then stop and think, before jumping to your next step. Have you ever used the informal tools of human senses individually or in combination, to find the source of your problems or assess your designs? Did you do this intentionally or accidentally?