Breadboards, stripboards and PCBs


By Orphi

I’ve written a lot of theory stuff recently, so let’s talk about practical stuff for a bit.

Putting in the big order

After researching online, I found that Farnell was about the best place to buy things. So I created an account, and ordered two items, mostly to see if it worked. Well obviously it did, and I ended up with a bench power supply and some breadboard.

I used the power supply and the existing wires I had to test out some of my LEDs. Well yes, they work. But I can buy a matching set of them for pennies, so there’s not much point struggling on with old, broken stuff.

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Fixing WordPress


By Orphi

I have previously written about how infuriating it is that you can’t just force WordPress to look nice.

Well, I eventually uncovered a button that allows you to noodle around with the raw CSS. I saw there was a button to edit the theme — but that’s going to get reverted next time a theme update happens. So I thought it was just impossible to fix (short of learning how to develop your own WordPress themes — which is a bit much like to get sensible rendering).

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Learn to count like a computer


By Orphi

Humans count in decimal, but computers count in binary. How does that work?

A recap of decimal

If you’re really ancient like me, you may remember a long obsolete technology known as “cassette tape”. You may even have seem an actual cassette player. And you may have noticed that they typically have a 3-digit revolution counter. For… some reason. (I think the idea is to allow you to fast-forward or rewind to specific points on the tape… except they’re way too inaccurate for that!) Older gas and electricity meters have a similar mechanism.

The way the counter works is quite simple. There are some number of plastic wheels, with the numbers from 0 to 9 printed on them. You zero the counter, so each wheel shows 0. And then the first wheel slowly rotates around, giving you 000, 001, 002, and so on. Eventually, the first wheel reaches 9. As the wheel continues to turn, it rolls back to 0 again. But a notch on the wheel causes the next wheel along to also rotate round one place, so instead of 009 being followed by 000 again, what actaully happens is 009 is followed by 010.

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WordPress hates tables


By Orphi

So today I attempted to write a post that has some tables in it. Suffice it to say, working with tables in WordPress is infuriatingly hard! I came damn close to rage-quitting when I discovered that WordPress won’t allow you to change the text alignment of table cells. I mean, seriously. How is anybody supposed to do anything with this miserable piece of software if it doesn’t allow even the most basic formatting?!

I screamed in agony when I discovered that the only way to align table cells is to manually edit the raw HTML. (Which the editor then won’t recognise as a table any more, and has to be treated as “custom HTML”. Yes, that’s right, the trivial task of aligning a text cell is “custom”. Whiskey-Tango-Foxtrot.)

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Bottom up, Part I: Gates & multiplexers


By Orphi

Logic gates

Computers are built from logic gates.

Now, you might think that computers are built from transistors. But that’s not strictly true. Most current computers happen to be built from transistors. However, the very first computers were built from electromechanical relays, and after that they were built from thermionic emission valves (AKA vacuum tubes). And today, yes, they’re build from transistors.

People tend to think of computers as being these sophisticated, highly refined black box machines that mortal minds could never possibly comprehend. In fact, there’s no reason why you can’t have purely mechanical computers. You could make a working computer out of lego — but only if you can figure out how to make logic gates out of lego.

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How a computer works — the short version


By Orphi

You can get a rough appreciation for how a computer works just by grasping a small hundful of ideas.

1. Numbers flow along busses

Computers represent numbers using electricity. They do this by turning circuits on or off. For example, imagine you have a bundle of 4 wires, each of which can be independently turned on or turned off. Now, we could turn all 4 wires on. Or we could turn all of them off. Or we could turn the left-most one on and all the others off. Or we could turn the two outermost wires off and the two in the middle on. Or several other possible combinations.

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Design goals


By Orphi

Having discovered that it looks at least plausible that I could build something, the next exercise is to decide what to build.

Prior work

Of course, it’s not exactly like I’m the first person to attempt to build a computer from scratch. Naturally, this is how the very first computers were created in the first place! But more than that, a little research reveals that there’s already a wide range of home-made computers out there, made by nerds like me who decided to make one because, why not?

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Setting up WordPress again


By Orphi

So, about 10 years after last using WordPress, I once again have a blog.

When I set this up ten years ago, my hosting provider offered, like, 6 possible themes. So I chose the one with the most green in it, obviously. It was wild and wacky and mildly over the top, and the font was awful… but since there is literally nothing I could do about it, I just kind of accepted that my blog would have to look lame.

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Genesis


By Orphi

How to make everything

Sometime last year, I was browsing around YouTube, when I stumbled upon a series of videos named “how to make everything”. They had one about making chocolate, another about making a suit, and so on.

But rather than just go out and buy the ingredients, the guy tries to actually make all this stuff from scratch, from the raw materials. Like, for the chocolate video, he actually flew all the way to South America and actually harvested the cocoa beans personally, and went through the whole process of fermenting, drying and roasting the beans. For the suit, he actually flew to Texas and personally picked cotton for, like, a day, and then spent another day spinning it into thread, and so on.

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