A NOR Gate For An ALU?

If you know anything about he design of a CPU, you’ll probably be able to identify that a critical component of all CPUs is the Arithmetic Logic Unit, or ALU. This is a collection of gates that can do a selection of binary operations, and which depending on the capabilities of the computer, can be a complex component. It’s a surprise then to find that a working CPU can be made with just a single NOR gate — which is what is at the heart of [Dennis Kuschel]’s My4th single board discrete logic computer. It’s the latest in a series of machines from him using the NOR ALU technique, and it replaces hardware complexity with extra software to perform complex operations.

Aside from a refreshingly simple and understandable circuit, it has 32k of RAM and a 32k EPROM, of which about 9k is microcode and the rest program. It’s called My4th because it has a Forth interpreter on board, and it has I2C and digital I/O as well as a serial port for its console.

This will never be a fast computer, but the fact that it computes at all is ts charm. In 2023 there are very few machines about that can be understood in their entirety, so this one is rather special even if it’s not the first 1-bit ALU we’ve seen.

Thanks [Ken Boak] for the tip.

A Compact Camera Running Linux? What’s Not To Like!

One of the devices swallowed up by the smartphone for the average person is the handheld camera, to the extent that the youngsters are reported to be now rediscovering 20-year-old digital cameras for their retro cool factor. Cameras aren’t completely dead though, as a mirrorless compact or a DSLR should still blow the socks off a phone in competent hands. They’ve been around long enough to be plentiful secondhand, which makes [Georg Lukas]’ look at a ten-year-old range of models from Samsung worth a second look. Why has a deep dive into old cameras caught our eye? These cameras run Linux, in the form of Samsung’s Tizen distribution.

His interest in the range comes from owning one since 2014, and it’s in his earlier series of posts on hacking that camera that we find some of the potential it offers. Aside from the amusement that it runs an unprotected X server, getting to a root shell is fairly straightforward as we covered at the time, and it turns out to be a very hackable device.

Cameras follow a Gartner hype cycle-like curve in the popularity stakes, so for example the must-have bridge cameras and compact cameras of the late-2000s are now second-hand-store bargains. Given that mirrorless cameras such as the Samsung are now fairly long in the tooth, it’s likely that they too will fall into a pit of affordability before too long. One to look out for, perhaps.

Tour A PCB Assembly Line From Your Armchair

Those of us who build our own electronics should have some idea of the process used to assemble modern surface-mount printed circuit boards. Whether we hand-solder, apply paste with a syringe, use a hotplate, or go the whole hog with stencil and oven, the process of putting components on boards and soldering them is fairly straightforward. It’s the same in an industrial setting, though perhaps fewer of us will have seen an industrial pick-and-place line in action. [Martina] looks at just such a line for us, giving a very accessible introduction to the machines and how they are used. Have a look, in the video below the break.

It’s particularly interesting as someone used to the home-made versions of these machines, to see the optical self-alignment and the multiple pick-and-place tools which are beyond the simpler pick-and-place machines you’ll find in a hackerspace. Multiple machines in a line are also beyond hackerspaces, so the revelation that the first machine is deliberately run slowly to avoid the line backing up is a valuable one.

At the end of the line is the reflow oven itself, through which the boards pass on a belt through carefully graded hot air zones. Certainly a step up from a toaster oven with an Arduino controller!

Sadly not all of us will be lucky enough to have such a line at our disposal, but pick-and-place projects come up here quite often. We did a teardown on the feeders from a Siemens machine a couple of years ago.

Continue reading “Tour A PCB Assembly Line From Your Armchair”

Why Do Rifa Capacitors Fail?

Anyone who works with older electronic equipment will before long learn to spot Rifa capacitors, a distinctive yellow-translucent component often used in mains filters, that is notorious for failures. It’s commonly thought to be due to their absorbing water, but based upon [Jerry Walker]’s long experience, he’s not so sure about that. Thus he’s taken a large stock of the parts and subjected them to tests in order to get to the bottom of the Rifa question once and for all.

What he was able to gather both from the parts he removed from older equipment and by applying AC and DC voltages to  test capacitors, was that those which had been used in DC applications had a much lower likelihood of exhibiting precursors to failure, and also a much longer time before failure when connected to AC mains.

Indeed, it’s only at the end of the video that he reveals one of the parts in front of him is an ex-DC part that’s been hooked up to the mains all the time without blowing up. It’s likely then that these capacitors didn’t perform tot heir spec only when used in AC applications. He still recommends replacing them wherever they are found and we’d completely agree with him, but it’s fascinating to have some light shed on these notorious parts.

Continue reading “Why Do Rifa Capacitors Fail?”

Apple Never Gave Them USB. Now, They’re Getting It For Themselves

These days we use USB as a default for everything from low-speed serial ports to high-capacity storage, and the ubiquitous connector has evolved into a truly multi-purpose interface. It’s difficult to believe then, that the first Apple Mac to be designed with a USB interface was shipped without it; but that’s the case with 1997’s grey Power Mac G3.

On the personality board are all the footprints for a single USB 1.1 port, but USB-hungry Apple fanboys had to wait for the translucent iMac and later G3 before they had a machine with the parts fitted. [Croissantking] is righting that particular wrong, by piecing together the missing Apple circuit using parts from contemporary cards for PCs. Over a long forum thread there are a few teething problems, but it certainly seems as though grey G3 owners will soon be able to have reliable USB upgrades.

If omitting USB from a 1997 Mac seems unexpected, it’s as well to remember how slow the first USB versions were. At the time SCSI was king in the high-speed peripheral world, and USB seemed more appropriate as a replacement for Apple Desktop Bus and the serial port. Even when they embraced USB they were reluctant to follow the standards of the PC world, as we remember finding out when for curiosity’s sake we tried swapping the mice and keyboards between an iMac and a Windows PC. We have USB’s success to thank for releasing Mac users from a world of hugely overpriced proprietary peripherals.

If you fancy hacking a ’90s PowerMac, make sure you get one that works.

Thanks [Doug] for the tip.

Why A Community Hackerspace Should Be A Vital Part Of Being An Engineering Student

Travelling the continent’s hackerspaces over the years, I have visited quite a few spaces located in university towns. They share a depressingly common theme, of a community hackerspace full of former students who are now technology professionals, sharing a city with a university anxious to own all the things in the technology space and actively sabotaging the things they don’t own. I’ve seen spaces made homeless by university expansion, I’ve seen universities purposefully align their own events to clash with a hackerspace open night and discourage students from joining, and in one particularly egregious instance, I’ve even seen a university take legal action against a space because they used the name of the city, also that of the university, in the name of their hackerspace. I will not mince my words here; while the former are sharp practices, the latter is truly disgusting behaviour.

The above is probably a natural extension of the relationship many universities have with their cities, which seems depressingly often to be one of othering and exclusion. Yet in the case of hackerspaces I can’t escape the conclusion that a huge opportunity is being missed for universities to connect engineering and other tech-inclined students with their alumni, enhance their real-world skills, and provide them with valuable connections to tech careers.

Yesterday I was at an event organised by my alma mater, part of a group of alumni talking to them about our careers.  At the event I was speaking alongside an array of people with varying careers probably more glittering than mine, but one thing that came through was that this was something of a rare opportunity for many of the students, to talk to someone outside the university bubble. Yet here were a group of engineers, many of whom had interesting careers based locally, and in cases were even actively hiring. If only there were a place where these two groups could informally meet and get to know each other, a community based on a shared interest in technology, perhaps?

It’s not as though universities haven’t tried on the hackerspace front, but I’m sad to say that when they fill a room with cool machines for the students they’re rather missing the point. In some of the cases I mentioned above the desire to own all the things with their own students-only hackerspace was the thing that led to the community hackerspaces being sabotaged. Attractive as they are, there’s an important ingredient missing, they come from a belief that a hackerspace is about its facilities rather than its community. If you were to look at a room full of brand-new machines and compare it with a similar room containing a temperamental Chinese laser cutter and a pair of battered 3D printers, but alongside a group of seasoned engineers in an informal setting, which would you consider to be of more benefit to a student engineer? It should not be a difficult conclusion to make.

Universities value their local tech industry, particularly that which has some connection to your university. You want your students to connect with your alumni, to connect with the local tech scene, and to ultimately find employment within it. At the same time though, you’re a university, you see yourselves as the thought leader, and you want to own all the things. My point is that these two positions are largely incompatible when it comes to connecting your engineering students with the community of engineers that surround you, and you’re failing your students in doing so.

Thus I have a radical proposal for universities. Instead of putting all your resources on a sterile room full of machines for your students, how about spending a little into placing them in a less shiny room full of professional engineers on their off-time? Your local hackerspace is no threat to you, instead it’s a priceless resource, so encourage your students to join it. Subsidise them if they can’t afford the monthly membership, the cost is peanuts compared to the benefit. Above all though, don’t try to own the hackerspace, or we’re back to the first paragraph. Just sometimes, good things can happen in a town without the university being involved.

It’s Difficult To Read An Audiophile Guide As An Analogue Engineer

Sitting on a train leaving the Hackaday Berlin conference, and Hacker News pops up Julian Shapiro with a guide to HiFi. What Hackaday scribe wouldn’t give it a click, to while away the endless kilometres of North European Plain!

It’s very easy as an analogue electronic engineer, to become frustrated while reading audiophile tracts, after all they have a tendency to blur superficial engineering talk with pseudoscience. There’s a rich vein of parody to be found in them, but nevertheless it’s interesting to read them because just sometimes the writer gets it and doesn’t descend into the world of make-believe. Continue reading “It’s Difficult To Read An Audiophile Guide As An Analogue Engineer”