The Sinclair ZX Spectrum Turns 40

April 26, 2022 by Jenny List 68 Comments

It’s an auspicious moment for retrocomputing fans, as it’s now four decades since the launch of the Sinclair ZX Spectrum. This budget British microcomputer was never the best of the bunch, but its runaway success and consequent huge software library made it the home computer to own in the UK. Here in 2022 it may live on only in 1980s nostalgia, but its legacy extends far beyond that as it provided an entire generation of tech-inclined youngsters with an affordable tool that would get them started on a lifetime of computing.

What Was 1982 Really Like?

Cover of Sincalir User, Sir Clive Sinclair as a magician — Sinclair User issue 3 captures the excitement surrounding the Spectrum launch.

There’s a popular meme among retro enthusiasts that the 1980s was a riot of colour, pixel artwork, synth music, and kitschy design. The reality was of growing up amid the shabby remnants of the 1970s with occasional glimpses of an exciting ’80s future. This was especially true for a tech-inclined early teen, as at the start of 1982 the home computer market had not yet reached its full mass-market potential. There were plenty of machines on offer but the exciting ones were the sole preserve of adults or kids with rich parents. Budget machines such as Sinclair’s ZX81 could give a taste of what was possible, but their technical limitations would soon become obvious to the experimenter.

1982 was going to change all that, with great excitement surrounding three machines. Here in the UK, the Acorn BBC Micro had been launched in December ’81, the Commodore 64 at the start of ’82, and here was Sinclair coming along with their answer in the form of first the rumour of a ZX82, and then the reality in the form of the Spectrum.

This new breed of machines all had a respectable quantity of memory, high-res (for the time!) colour graphics, and most importantly, sound. The BBC Micro was destined to be the school computer of choice and the 64 was the one everybody wanted, but the Spectrum was the machine you could reasonably expect to get if you managed to persuade your parents how educational it was going to be, because it was the cheapest at £125 (£470 in today’s money, or about $615). Continue reading “The Sinclair ZX Spectrum Turns 40” →

Can You Identify This Mystery Unicode Glyph?

April 24, 2022 by Jenny List 58 Comments

For anyone old enough to have worked with the hell of multiple incompatible character sets, Unicode has been a liberation; a true One Character Set To Contain Them All. We have so many Unicode characters to play with that there’s a fascinating pursuit in itself in probing at the obscure corners of what can be rendered on screen as a Unicode glyph. With so many disparate character sets having been brought together to make the Unicode standard there are plenty of unusual characters to choose from, and it’s one of them that [Jonathan Chan] has examined in detail.

U+237C ⍼, or the right angle with downwards zigzag arrow, is a mysterious Unicode symbol with no known use and from an unknown origin. XKCD featured it as a spoof “Larry Potter”, but as [Jonathan]’s analysis shows it’s proving impossible to narrow down where it came from. Mystical cult symbol? Or perhaps fiscal growth in an economy in which time runs downwards? Either way, when its lineage has been traced into the early 1990s with no answer to the question it appears that there may be a story behind it.

Hackaday readers never cease to amaze us with the breadth of their knowledge, ingenuity, and experience, so we think it’s not impossible that among you there may be people who will turn and pull a dusty computer manual from the shelf to give us the story behind this elusive glyph. We’d love to hear in the comments below.

Meanwhile if Unicode sparks your interest, we’ve given it a close look in the past.

Thanks [Jonty] for the tip.

A FET Oscilloscope Probe For Higher Frequencies

April 23, 2022 by Jenny List 8 Comments

It’s a problem that has dogged electronic engineers since the first electrons were coaxed along a wire: that measuring instruments can themselves disrupt the operation of a circuit. Older multimeters for example had impedances low enough to pull resistor values, thus our multimeters today have high-impedance FET inputs. [Christoph] faced it with his oscilloscope probe, its input capacitance was high enough to put unacceptable load on a crystal oscillator and stop it oscillating. He thus built a FET input probe for higher RF frequencies, and its construction is an accessible view of wideband RF instrumentation design.

The circuit is a very simple one using a dual-gate FET, but the interest comes in the PCB and screening can design to ensure good RF performance. Off-the-shelf cans have four sides, so to accommodate the circuit one wall of the can had to be removed. The end result is a tiny PCB with miniature co-ax connectors for power and signal, which when characterised was found to have a 1.3 GHz bandwidth and a very low input capacitance.

If the language of RF design is foreign to you, may we recommend [Michael Ossmann]’s talk at a Superconference a few years ago.

The Honda Takedown: How A Global Brand Failed To Read The Room

April 21, 2022 by Jenny List 141 Comments

Perhaps the story of the moment in the world of 3D printing concerns a Japanese manufacturer of cars and motorcycles. Honda has sent a takedown notice requesting the removal of models starting with the word “Honda” to the popular 3D printing model repository site Printables. It’s left in its wake puzzlement, disappointment, and some anger, but what’s really going on? Perhaps it’s time to examine what has happened and to ponder what it means for those who put online printable parts and accessories for cars or any other item manufactured by a large corporation.

If You Make Something, What Rights Do You Have?

Soichiro Honda with his 1964 Formula 1 car — Soichiro Honda, famous for being an engineer rather than a serial litigator. Roderick Eime, CC BY 2.0.

The story is that as far as we can glean from reports online, the takedown notice was sent only to Printables by the European arm of Honda, and was pretty wide-ranging with any Honda-related model in its scope. Printables complied with it, but as this is being written there are plenty of such models available from Thingiverse and other model repository sites.

Anyone who makes a career in content creation has by necessity to have a working knowledge of copyright and intellectual property law as it’s easy for the unwary to end up the subject of a nasty letter, so here at Hackaday while we’re not lawyers this is a subject on which we have some professional experience. What follows then is our take based on that experience, our view on Honda’s motivation, and whether those of you who put up 3D models have anything to worry about. Continue reading “The Honda Takedown: How A Global Brand Failed To Read The Room” →

Gaskets, Can They Be 3D Printed?

April 20, 2022 by Jenny List 74 Comments

Anyone who’s owned an older engine, whether it be in a car, motorcycle, or garden machine, will at some time have been faced with the need for a gasket. Even when the gasket is readily available there may be an imperative to fix the engine rather than wait for the part to arrive, so it’s common to make your own replacements. Simple ones are easy to cut from thin card, but if you’ve ever tried to do this with a really complex one you’ll know the pain of getting it right. This is the problem tackled in a video from [the_eddies], who has explored the manufacture of replacement gaskets by 3D printing.

The advantages of CAD and easy manufacture are obvious, but perhaps many common plastics might not perform well in hot or oily environments. For that reason he settles on TPU filament, and gives it a test in a bath of 2-stroke fuel mix to see how well it resists degradation. It passes, as it does also when used with a carburetor, though we’d be curious to see the results of a long-term test. We’ve placed the video below the break, so reach your own conclusions.

Gaskets have featured here before, and if you’re interested then there are other machines which can be used to make them.

Continue reading “Gaskets, Can They Be 3D Printed?” →

A Line Follower With No Brains

April 19, 2022 by Jenny List 26 Comments

A line follower is a common project for anyone wishing to make a start in robotics, a small wheeled device usually with some kind of optical sensor which allows it to follow a line drawn on the surface over which it runs. In most cases they incorporate a small microcontroller or perhaps an analogue computer which supplies power and steering control, but as the Crayon Car from [Greg Zumwalt] demonstrates, it’s possible to make a line follower without any brains at all.

This seemingly impossible feat is achieved thanks to the line and road surface, it runs on a piece of paper over which the line is drawn with a crayon. The robot has a single straight-line drive wheel at one end and a pair of driven rollers at 90 degrees to each other at the other end, with the magic happening due to the difference in friction between paper and crayon. The robot follows a circular track with no problem, and while we can see it’s not without flaws we doubt it would be possible to make a simpler follower.

Sharp-eyed readers will have noticed that this is not the first line follower we’ve shown you which claims to have no brains, but we’d claim that since the previous machine had an analogue circuit, this one is a more worthy contender to the crown.

Continue reading “A Line Follower With No Brains” →

Bare Metal Gives This Pi Some Classic Synths

April 19, 2022 by Jenny List 18 Comments

We’re used to seeing the Raspberry Pi crop up in a wide range of the projects we show you here, but it’s fair to say that they usually feature some sort of operating system. There’s another way to use a Pi, more akin to using a microcontroller such as the Arduino: by programming it directly, so-called bare-metal programming. MiniDexed is an example, and it copies a classic Yamaha professional synthesiser of the 1980s, by emulating the equivalent of eight of the company’s famous DX7 synthesisers in one unit. It takes almost any Pi, and with the addition of an audio board, a rotary encoder, and an LCD display, makes a ready-to-go unit. Below the break is a video of it in operation.

It’s fair to say that we’re not experts in Raspberry Pi bare metal programming, but it’s worth a diversion into the world of 1980s synthesisers to explore the DX7. This instrument was a staple of popular music throughout the 1980s and was a major commercial success for Yamaha as an affordable FM synthesiser. This was a process patented at Stanford University in the 1970s and subsequently licensed by the company, unlike other synths of the day it generated sound entirely digitally. It’s difficult to overestimate the influence of the DX7 as its sound can be heard everywhere, and it’s not impossible that you own a Yamaha FM synth even today if you have in your possession a sound card.

Curious about the DX7? Master chip-reverse-engineer [Ken Shirriff] exposed its secrets late last year.

Continue reading “Bare Metal Gives This Pi Some Classic Synths” →