The Acorn Archimedes At 30

The trouble with being an incidental witness to the start of something that later becomes world-changing is that at the time you are rarely aware of what you are seeing. Take the Acorn Archimedes, the home computer for which the first ARM processor was developed, and which has just turned 30. If you were a British school pupil in 1987 who found a pair of the new machines alongside the row of BBC Micros in the school computer lab, for sure it was an exciting event, after all these were the machines everyone was talking about. But the possibility that their unique and innovative processor would go on to spawn a line of successors that would eventually power so much of the world three decades later was something that probably never occurred to spotty ’80s teens.

[Computerphile] takes a look at some of the first Archimedes machines in the video below the break. We get a little of the history and a description of the OS, plus a look at an early model still in its box and one of the last of the Archimedes line. Familiar to owners of this era of hardware is the moment when a pile of floppies is leafed through to find one that still works, then we’re shown the defining game of the platform, [David Braben]’s Lander, which became the commercial Zarch, and provided the template for his Virus and Virus 2000 games.

The Trojan Room Coffee Cam Archimedes, on display at the Cambridge University Computing Department.
The Trojan Room Coffee Cam Archimedes, on display at the Cambridge University Computing Department.

We see the RiscOS operating system booting lightning-fast from ROM and still giving a good account of itself 20 years later even on a vintage Philips composite monitor. If you were that kid in 1987, you were in for a shock when you reached university and sat down in front of the early Windows versions, it would be quite a few years before mainstream computers matched your first GUI.

The Archimedes line and its successors continued to be available into the mid 1990s, but faded away along with Acorn through the decade. Even one being used to power the famous Trojan Room Coffee Cam couldn’t save it from extinction. We’re told they can still be found in the broadcast industry, and until fairly recently they powered much of the electronic signage on British railways, but other than that the original source of machines has gone. All is not lost though, because of course we all know about their ARM joint venture which continues to this day. If you would like to experience something close to an Archimedes you can do so with another computer from Cambridge, because RiscOS is available for the Raspberry Pi.

Sit back and enjoy the video, and if you were one of those kids in 1987, be proud that you sampled a little piece of the future before everyone else did.

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Testing the Outernet Dreamcatcher SDR

What do you get when you cross an ARM-based Linux PC and an RTL-SDR? Sounds like the start of a joke, but the answer is Outernet’s Dreamcatcher. It is a single PCB with an RTL-SDR software defined radio, an L-band LNA, and an Allwinner A13 processor with 512MB of RAM and a 1 GHz clock speed. The rtl-sdr site recently posted a good review of the $99 board.

We’ll let you read the review for yourself, but the conclusion was that despite some bugs, the board was no more expensive than pulling the parts together separately. On the other hand, if you uses, for example, a Raspberry Pi 3, you might expect more support and more performance.

Despite the L-band hardware, there is a bypass antenna jack that allows you to receive other frequencies. There’s also two SD slots, one to boot from and another for storage. Several pieces of software had trouble running on the somewhat sluggish CPU, although some software that is optimized for the particular processor used fared better. You can read the details in the review.

The board is interesting, although unless you have a special packaging problem, you are probably as well off to combine a Pi and a dongle, as we have seen so many times before. If you have more horsepower you can even make the Pi transmit, although we’d suggest some filtering if you were going to do that for real.

Robotic Arms Controlled By Your….. Feet?

The days of the third hand’s dominance of workshops the world over is soon coming to an end. For those moments when only a third hand is not enough, a fourth is there to save the day.

Dubbed MetaLimbs and developed by a team from the [Inami Hiyama Laboratory] at the University of Tokyo and the [Graduate School of Media Design] at Keio University, the device is designed to be worn while sitting — strapped to your back like a knapsack — but use while standing stationary is possible, if perhaps a little un-intuitive. Basic motion is controlled by the position of the leg — specifically, sensors attached to the foot and knee — and flexing one’s toes actuates the robotic hand’s fingers. There’s even some haptic feedback built-in to assist anyone who isn’t used to using their legs as arms.

The team touts the option of customizeable hands, though a soldering iron attachment may not be as precise as needed at this stage. Still, it would be nice to be able to chug your coffee without interrupting your work.

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Digital Clock Goes with the Grain

This good-looking clock appears to be made out of a block of wood with LED digits floating underneath. In reality, it is a block of PLA plastic covered with wood veneer (well, [androkavo] calls it veneer, but we think it might just be a contact paper or vinyl with a wood pattern). It makes for a striking effect, and we can think of other projects that might make use of the technique, especially since the wood surface looks much more finished than the usual 3D-printed part.

You can see a video of the clock in operation below. The clock circuit itself is nothing exceptional. Just a MAX7218 LED driver and a display along with an STM32 ARM processor. The clock has a DHT22 temperature and humidity sensor, as well as a speaker for an alarm.

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An Education on SoC using Verilog

[Bruce Land] is one of those rare individuals who has his own Hackaday tag. He and his students at Cornell have produced many projects over the years that have appeared on these pages, lately with FPGA-related projects. If you only know [Land] from projects, you are missing out. He posts lectures from many of his classes and recently added a series of new lectures about developing with a DE1 System on Chip (SoC) using an Altera Cyclone FPGA using Verilog. You can catch the ten lectures on YouTube.

The class material is different for 2017, so the content is fresh and relevant. The DE1-SOC has a dual ARM processor and boots Linux from an SD card. There are several labs and quite a bit of background material. The first lab involves driving a VGA monitor. Another is a hardware solver for ordinary differential equations.

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Rusty ARM

You’ve probably heard that Rust is a systems programming language that has quite the following growing. It purports to be fast like C, but has features like guaranteed memory and thread safety, generics, and it prevents segmentation faults. Sounds like just the thing for an embedded system, right? [Jorge Aparicio] was frustrated because his CPU of choice, an STM32 ARM Cortex-M didn’t have native support for Rust.

Apparently, you can easily bind C functions into a Rust program but that wasn’t what he was after. So he set out to build pure Rust programs that could access the device’s hardware and he documented the effort.

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STM32 Analog Converter Phase Noise

[Avian] has been using STM32 ARM processors to sample RF for a variety of applications. At first, he was receiving relatively wide TV signals. Recently, though, he’s started dealing with very narrow signals and he found that his samples had a lot of spread in the frequency domain that he didn’t expect.

What followed was some detective work that resulted in a determination that phase noise was the culprit. But why? [Avian] took some measurements and noticed that the phase noise almost exactly matched the phase noise specification for the STM32’s phase locked loop (PLL).

Unfortunately, there didn’t seem to be a good way to avoid using the PLL without major changes to the rest of the circuit. However, it was quite the learning experience and something to be aware of when counting on built-in converters for high-accuracy measurements.

One of the best things about this post is the references to more information. There’s a great explanation of phase noise, as well as a specific application note about clock jitter and analog converters.

We’ve talked about phase noise in direct digital synthesis a few times. But usually, it is pretty obvious like when you are asking a CPU to double as an RF transmitter. [Avian’s] post was a bit more of a detective story.