Tag: How to Build a Computer

Contributor Post Created with Sketch. Getting Myself Phished, a Quick Yakking about Hacking


Phishing is the email version of pretending to be someone you’re not. The end goal is to talk some dupe into clicking on your link, to either steal their information or otherwise break into their computer. I know a thing or two about what this is and how it works, and yet I clicked on the link last night. Let’s go straight to story mode, shall we?

I see an email in my inbox, from Admin PayPal. Subject line “Your account has been limited. (Code: E8 -s0me-malarky)” I open the email. I’ll screenshot the message for you to see it for yourself.

Contributor Post Created with Sketch. How to Build a Computer 37: CVD II, This Time It’s Personal


Last time, if you’ll recall, I discussed the basic idea of a chemical vapor deposition system, and described how you’d use it to deposit silicon onto your wafer. Today we’re following rather directly from that post, where we answer some important questions. Questions like “What if I don’t want to put down silicon? What other things can you offer me?” Well, for starters

SiCl4(g) + 2H2(g) + O2(g) —> SiO2(s) + 4HCl(g) ~900 C

Contributor Post Created with Sketch. How to Build a Computer 36: Chemical Vapor Deposition


No matter how much fun you’re having etching silicon, applying and stripping photoresist, or implanting ions, sooner or later you’re going to have to actually put down some lines. Gotta build a circuit eventually. Chemical Vapor Deposition (CVD) is one of the main ways this gets done. Let’s have a look at what we’re doing, shall we?

If I had known I was going to use this picture at least three times I might have put a little more effort into the sketching.

What you’re looking at is a jump over a wire. You have two wires that need to cross but not touch each other, you gotta do something like this. Let’s go over the process to get there:

Contributor Post Created with Sketch. How to Build a Computer 35: Anisotropic Etching


Last time we talked about how to make tiny little holes in silicon using harsh acids. Wet etching is fine and all, but sometimes you just can’t make a feature small enough. You’re limited by the aspect ratio. That is, how wide it is versus how tall it is. A post hole has a high aspect ratio because it’s much deeper than it is wide. A strip mine is a pretty low aspect ratio hole. The difficulty with making high aspect ratio holes in your silicon is that your etchant is going to etch down, yes, but it’s also going to etch towards the sides.

Before we get into dry etching there’s one more trick for making an anisotropic (uh, it etches downward quicker than it goes sideways. Literally the word means not-the-same-in-all-directions.) wet etch. What happens if you do your etching with a strong base instead of a strong acid? As it turns out, and for no reason, I’ve managed to determine, a strong base will etch one crystal face preferentially.

Contributor Post Created with Sketch. How to Build a Computer 34: Etching


We’re moving back from the series on measurement to the whole process of making computer bits out of silicon. Way back, starting with Computers 7, I started a series on patterning; how you can take an idea and draw it small enough that you can apply that pattern to these really tiny circuits. I went over, step by step, each thing you need to do to create the pattern. I skipped entirely the bit where I tell you what, exactly, you do with one of those patterns when you’ve got them. This is the first of a couple of articles that fit, in manufacturing terms, between Computers 15 (Developing), and 16 (Stripping). You develop your pattern on with photoresist, this is how you make it permanent.

We’ll start with etching. Broadly speaking ‘etching’ covers any process where you start with more material and end up with less material. I mean aside from gambling. Let’s say you’ve got your silicon wafer, you want to etch some of that silicon away. To do this we start by burning your wafer. …Okay, perhaps that’s poor phrasing. Put the flamethrower down and I’ll describe what I mean. To protect your silicon wafer from the damage the etching process would do to it we’re going to want to mask it, with a silicon dioxide layer. Heat your wafer up in the presence of oxygen and this happens:

Contributor Post Created with Sketch. How to Build a Computer 33: Atomic Force Microscopy!


Atomic Force Microscopy is a refinement of that long and hallowed scientific tradition: poke it with a stick and see what happens. Picture, if you will, a blind man walking across the street. He taps the ground with his cane, profiling the height of the surface. That tells him where the curbs are; he doesn’t trip because he knows when to step up and step down. Now picture that blind man in a skate park, full of ramps and contours. He could, by painstaking effort, tap his cane up and down the entire area of the skate park and build up a picture in his mind where all the half-pipes lay, even though he can’t see ’em himself. Now picture him in that same skate park, doing kick-flips and grinding like a pro. Because that sounds awesome.

Three square microns of (highly ordered pyrolitic) graphite. A friend of mine measured this as part of a school project we worked on. This is after a metaphorical baseball bat to the head of mathematical smoothing.

Atomic Force Microscopy builds up a portrait of the surface of a thing by rubbing a tiny, tiny needle across it, and reading it like you’d read the grooves on a record. Heck, you could probably play it like a record too, only it’d sound all staticky because nobody bothered to lay down music on that spot to begin with. (Although…)

Contributor Post Created with Sketch. How to Build a Computer 32: X-Rays


I think x-rays have had their dramatic potential shortchanged by the way they’re actually useful. You hear “gamma rays” and your mind is drawn to the Incredible Hulk and how he gained his bright purple shorts. Cosmic Rays? Space madness! But when your mind turns to x-rays you start thinking “dentistry.” Much less exciting.

Right. Computers. Today we’re going to spend one more post on Electron Microscopy, and another way these things are useful. This one is actually pretty straightforward from topics we’ve already covered. I’m sure y’all have been taking notes, and know immediately that I’m referring to Computers 5: Fundamental Chemistry, where I described the process of prodding electrons into giving up photons. I’ll save you the reread, even though jokes about New Jersey never get old. Here are the useful bits:

Contributor Post Created with Sketch. How to Build a Computer 31: Sputtering


Today we answer an important question: “How do I coat things in metal; even things that don’t want to be coated in metal?” You want to plate gold onto you Sacajawea dollar, that’s easy enough. You can use electricity to get one metal to stick to another. You want to cover Jill Masterson you use gold paint. But let’s say you’ve got a little plastic doohickey you want to look at under an SEM. Plastic famously refuses to conduct electricity. So how do you defeat the charging problems? (The charging problems that we mentioned last time. You were paying attention, weren’t you?) The answer is you sputter coat it. And this week I’ll be explaining what that means.

Also in the SEM lab; you can tell by the example images they’ve stuck into the window.

Start with an Argon plasma. Hmm… maybe let’s start a little earlier than that. A plasma is a gas where the atoms have an electron stripped off. Also, the stripped off electrons. You’ve got to keep your plasma at a pretty high energy, otherwise your atoms recapture their electrons and you end up with a boring ol’ gas. If you’re the Sun then you can make a plasma by heating up these gases to an enormous temperature. On Earth that’s less convenient, so we use electricity.

Contributor Post Created with Sketch. Recommended by Ricochet Members Created with Sketch. How to Build a Computer 30: SEMsational


This is a continuation of last time’s discussion on Electron Microscopy. In that one, we covered the question of why you’d want one of these and gave a summary of how you’d work one. Take some electrons, throw it at your sample, and watch what bounces off for information. Sounds so simple when we put it that way, right? This week we’re talking about what happens when you actually buckle down to do it in practice.

Taken from Chem lab, when there weren’t any chem techs around to stop me.

Okay, just looking at the thing isn’t doing me much good. What’s going on there, and why? Start from the top. That bottle on the left? That’s for liquid nitrogen, used in the x-ray detector. (Neat! Why do we want to detect x-rays? That’s a subject for a future column.) The cylinder on top marked “GEMINI” is your column; the electron gun is in the top, and the rest of it contains the magnets for focusing and directing the electron beam. The cube-ish box it’s sitting on is your sample chamber; the front pulls out to reveal the stage where you’d put your puck holding the samples. The dark grey table surface is granite, used to lend stability to the whole apparatus. The cabinet it’s sitting on contains electronics and the vacuum pumps. Now let’s get to how all that works together.

Recommended by Ricochet Members Created with Sketch. Quote of the Day: Computers


“On two occasions, I have been asked [by members of Parliament], ‘Pray, Mr. Babbage, if you put into the machine wrong figures, will the right answers come out?’…I am not able rightly to apprehend the kind of confusion of ideas that could provoke such a question.”
Charles Babbage, Passages from the Life of a Philosopher (1864), p. 67

Computers. When designed properly, they do precisely what they are told. They do not interpret, they need to be explicitly instructed on what exactly to do. However, when you get them going, they give you incredible capabilities. During WW2, people would have sacrificed armies to obtain the computing power in your cell phone. Even a simple flip phone has more power than all the computers in existence at the time. Charles Babbage could have revolutionized history, had manufacturing been up to the task — William Gibson’s novel The Difference Engine posits just such a future. (It was the beginning of the Steampunk genre)

Contributor Post Created with Sketch. Recommended by Ricochet Members Created with Sketch. How to Build a Computer 29: Electron Microscopy


For the next couple of posts, we’ll be sauntering through the science of measurement. To put it simply, computer bits are really, really small. So as you wander through the world of building them how do you know you’ve made the thing right? Well, let’s start simple. You can just look at ’em. I could go on a great big tear about optical microscopy which is still an important subject, and relevant. The problem with it is that I just don’t find the subject very interesting. Still, you get some neat images.

This is my fingerprint, photographed on the background of one of them hard drive platters I ripped out of that drive in the video. FBI please ignore.

To understand why you need the electron microscope it helps to spend some time with an optical microscope. The majority of the time I spent looking at parts I spent looking through an optical microscope, not on the SEM. Largely because Chem Lab owned the SEM, and they get all fidgety when someone else touches their stuff. Briefly though, I think I can demonstrate the usefulness of an electron microscope with two images.

Contributor Post Created with Sketch. Recommended by Ricochet Members Created with Sketch. How to Build a Computer 28: Video Edition!


Coming to you taped from the Wastes of Wisconsin Winter we present a special video edition of how to build a computer. In this post I take apart a hard drive and look at the bits piece by piece. Thrills, chills, blood and laughter, folks this film has it all! And at a price so low I’m practically giving it away.

Contributor Post Created with Sketch. Recommended by Ricochet Members Created with Sketch. How to Build a Computer 27: Data Recovery


We’ve covered the physical aspects of a hard disk drive, tonight we’ll touch on the way data is organized on the drive, by covering those two most important topics; keeping secrets and ferreting other people’s out.

In this case describing the times this joke has been used since it was last funny.

We’ll start by deleting files: Let’s say that I’ve got a backlog of old and worn-out memes to purge. That’s no problem, you just move them from the exquisitely detailed and organized archive of these things into the trash can, but that doesn’t actually erase anything. Bill Gates, knowing that we mere mortals are flawed and prone to regret, keeps your trashed files around in case your stale jokes may, someday in the future, be called for again. But we’re stronger than that. So we empty the trash folder (or, pro-tip; on a Windows box if you hold down ‘Shift’ as you delete a file the file doesn’t go to the trash at all; it empties automatically.)

Contributor Post Created with Sketch. Recommended by Ricochet Members Created with Sketch. How to Build a Computer 26: Spindles and Platters and So Forth


We’ve discussed what it means to actually store information on a hard disk drive, how you magnetize it and how you pull that information off. Neat stuff, but a bit heavy on the abstract physics. Today we’re going to zoom out a bit and look at the mechanical bits of how hard drives work. Here, let me start you off with a picture. Take a look at these two hard drives (conveniently cracked open for viewing purposes), one I borrowed from the boss man, and the other I picked up off the “Free Stuff” shelf when they moved the engineering department. Tell me which you think stores more data:

None of the above. Neither of is ever going to run again. Look at that dust!

Now I’ve actually got no idea on the history of these two drives, what year they were built, their listed capacity. Couple points of difference tell me the one on the left is older, and stores far less information:

Contributor Post Created with Sketch. Recommended by Ricochet Members Created with Sketch. How to Build a Computer 25: The Magnetoresistive Effect


Our story starts with Lord Kelvin, one of the great old school physicists. You can read about his career from John Walker’s old Saturday Night Science. Actually, at the point he enters this story I don’t think Kelvin had made lord yet; he was just some bloke named Thompson. This Thompson fellow was playing around with magnets and electricity and that sort of thing. What he discovered is that you can change the resistance of a wire with a magnetic field. And furthermore that that change in resistance depends on the angle between the wire and the magnetic field.

Let’s take that a little more slowly. Change in resistance when you’re in a magnetic field? Okay, I can buy that; there’s all this nonsense about wires and magnets and whatnot that I’ve been blathering about up until this point. Angle? The resistance in your wire will vary a great deal whether it’s parallel or antiparallel to the magnetic field on your disk. (Antiparallel means parallel, but facing the other direction. The northbound lane on a highway is antiparallel to the southbound lane.) If your wire is running current right-to-left and your magnetic field is pointed left-to-right then your wire’s resistance is at it’s highest because of your antiparallel configuration.

Contributor Post Created with Sketch. Recommended by Ricochet Members Created with Sketch. How to Automate a Job Out of Existence


This is an elaboration of a comment I made in @indymb ‘s post “Is there any point in writing to a Congressperson?” and I’m indebted to him and @Misthiocracy (who has experience working for a Canadian Member of Parliament, I understand) for the details on how all this works. Briefly, we’ll look at a simple task done every day in the houses of government and at how we’d train a computer to do it better.

Briefly, as you may have expected, the letter to your Senator isn’t so much read as processed for the minimum amount of information and interaction required. I’ll quote the meat of his description of the process and then describe how I’d go about automating it. You’re encouraged to go back and read his post (and it should go without saying on Ricochet but the comments too).

Contributor Post Created with Sketch. Recommended by Ricochet Members Created with Sketch. How to Build a Computer 24: Reading and Writing


Last time we discussed electricity, magnetism, and how you can generate a magnetic field with an electric current. You know what? Let’s jump straight to the kielbasa:

You could start with a salad, but why bother?

If you run a current through the wire you generate a magnetic field in the sausage (which ought to be a magnetizable metal, naturally), and a field between the prongs. Okay, we can use that thing to make a magnetic field, and use it to write fixed magnetic spots to a disk. The question we left off with is ‘how do you read it?’ Actually, I skipped a step. There’s still one important distinction to be drawn in how you write. Why does the magnetic field still write things if the platter isn’t in between those prongs?

Contributor Post Created with Sketch. Recommended by Ricochet Members Created with Sketch. How to Build a Computer 23: Magnets


Hard Disk Drives record data using a technology long known to baffle juggalos. The read/write head uses magnets to store information on those disks. How? Why? What does that even mean? Let’s jump in.

What makes a magnet a magnet? Moving electricity. When you get down to the atomic level atoms are magnetic because their electrons are spinning. Glomp a bunch of those atoms together (like sticking magnets one to another) and you have a grain. Get enough grains lined up in the same direction and you have a permanent magnet.

Contributor Post Created with Sketch. Recommended by Ricochet Members Created with Sketch. How to Build a Computer 22: Hard Disk Drives


We’re going to take a jaunt entirely out of sequence here, moving from circuits and silicon into larger scale components. Today we’re talking about hard disk drives. Why? Because it’s a fun and interesting technology, because I know a thing or two about it from first-hand experience, but mostly because I’ve got a book to return. And so we’ll take a quick dive into the world of hard disk drives to see what, as the bear over the mountain intended, we can see.

An example HDD. Entirely too dusty to be functional.

Note the term; usually, we refer to these things as ‘hard drives’ and don’t bother to distinguish what kind it is. In the olden days, you had a hard drive and you had a floppy drive. A hard disk drive (hereafter HDD) contains a spinning platter that has the information magnetically encoded on it. A floppy drive also had a spinning platter with information on it, but that spinning part was bendable. For all you youngsters out there your “Save” icon is supposed to look like a floppy disk. It dates back to the times when people actually saved files for storage on one of ’em. The structure of the disks was rigid, you didn’t see the floppy part until you took the thing apart.

Contributor Post Created with Sketch. Member Post


As a kid in the Boy Scouts we’d go camping occasionally at Fort Gibson. This, you see, was the name the eponymous Mr. Gibson gave to his extensive tract of land along the south fork of the Flambeau River. Being a firm proponent of the principle that Men are just Boys with bigger Toys he […]

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