Custom PC, Issue 184

Custom PC Issue 184Hobby Tech this month takes a look at a trio of very different products: the Clockwork GameShell modular hand-held console, the Dexter GiggleBot BBC micro:bit-powered robot, and the Coinkite Coldcard hardware cryptocurrency wallet.

First, the Coldcard. Designed by the company behind the Opendime (reviewed in Issue 175, and dead due to an apparent design flaw a week later), the Coldcard is roughly the size of a small stack of credit cards but provides a full hardware wallet for the Bitcoin and Litecoin cryptocurrencies. At least, that’s the theory: sadly, in practice, the device proved difficult to use owing to software glitches, hardware flaws, and a lack of third-party software support which reduces you to using only one wallet package to interface with the Coldcard.

The GiggleBot, by contrast, is a significantly more polished product. While the documentation still needs work, the robot itself – featured two individually-addressable motors, a line- or light-following sensor board, RGB LEDs, and expansion potential from Grove-compatible connectors and a pair of servo headers – is exceptionally impressive, and a great introduction to basic robotics for younger programmers. Those looking to make the leap from the block-based MakeCode environment to Python, though, will discover that the two libraries are far from equivalent in terms of feature availability – something that, again, will hopefully be addressed in the future.

Finally, the Clockwork GameShell. Produced following a successful crowdfunding campaign, the device is based around a Raspberry Pi-like single-board computer dubbed the Clockwork Pi and runs a customised Linux distribution with neat menu system. Its internals, interestingly, are modular, with each contained inside a snap-together transparent plastic housing – a decision which makes for a slightly bulky Game Boy-like outer shell and, sadly, is the direct cause of some overheating problems for the system-on-chip (SoC) during more intensive games like Quake. These issues, though, are largely outweighed by sheer novelty value: a few minutes of FreeDoom in the palm of your hand is sure to raise a smile.

The full reviews can be read in Custom PC Issue 184, available from your nearest supermarket, newsagent, or digitally via Zinio and similar services.

Custom PC, Issue 175

Custom PC Issue 175This month’s Custom PC is a bit of a Halfacree takeover, boasting a whopping 15 pages of my content: a seven-page guide to building a Raspberry Pi-powered vintage gaming console, a three-page look at the Spectre and Meltdown vulnerabilities, and my usual five-page Hobby Tech column with reviews of the Coinkite Opendime, iFixit Pro Tech Toolkit, and Brian Bagnall’s Commodore: The Amiga Years.

First, the vintage gaming feature. Building on a brief from editor Ben Hardwidge, I wanted to do something a little more in-depth than the usual how-to guide. The result is a seven-page feature which begins with a look at the wealth of accessories available to turn a Raspberry Pi or other single-board computing into a powerful emulation station, a two-page expert guide to the legalities of emulation in the UK, step-by-step instructions on downloading, installing, and configuring the RetroPie on a Raspberry Pi, and a look at entirely legitimate sources for read-only memory (ROM) game images.

While I’m fully equipped to handle the how-to and look-at-the-shiny-things sections of the guide myself, the legal aspect required an expert eye kindly provided by Eaton Smith LLP partner Chris Taylor. Legal counsel to a variety of game development and publishing companies, Chris kindly walked through the legalities of developing, downloading, and using emulation software and hardware under UK law – and even threw in a cheeky topical reference to Ernest Cline’s Ready Player One ahead of the release of its film adaptation. I’m also grateful to The Internet Archive’s software curator Jason Scott for taking the time to discuss the Archive’s vast trove of software and in-browser emulation functionality.

Meltdown and Spectre, meanwhile, are a lot less fun. The names given to a quartet of security vulnerabilities hard-baked in to the vast majority of processors built since the 1990s, Meltdown and Spectre are unarguably the worst things to happen to the computer industry since the death of the Commodore Amiga. My three-page look discusses the vulnerabilities, how they can be exploited to gain access to supposedly-protected information, and what companies are doing to fix the problems – and, spoiler, the conclusion there is “not nearly enough.” Since the piece was written, though, there’s one thing to note: installation of the KB4056892 patch for Windows 10 includes faulty microcode protection from Intel which can cause systems to reboot spontaneously, which is resolved through the installation of KB4078130 at the cost of disabling protections against one of the two Spectre vulnerabilities.

Finally, Hobby Tech itself opens with a look at the clever but fragile Opendime from cryptocurrency start-up Coinkite. Designed to turn Bitcoin into a digital bearer bond, an Opendime creates a private key which is stored in a secure enclave accessible only by irrevocably modifying the device by popping off a small surface-mount resistor. So long as the resistor is intact, the theory goes, nobody has access to the private key – meaning you can accept the device as payment without risk. Sadly, since my fairly glowing review was written two things have changed: the Opendime I’ve been carrying around on my keyring has unsealed itself without any visible damage to the resistor or the heatshrink which protects it, an issue Coinkite’s founder and support team have singularly failed to address, and the high transaction fees on the Bitcoin network have dropped from around £20 to around 20p meaning one of the major benefits of using a £15 USB device for in-person transactions has been lost.

The iFixit Pro Tech Toolkit, by contrast, is a significantly happier story. I’ve long been a fan of iFixit’s teardowns and the software they developed for presenting the information, so a toolkit with the iFixit seal of approval was high on my want list. Having now received one, I can confirm it’s no disappointment: from the high-quality tools, all bundled with the express intention of making it as easy as possible to dismantle modern electronics, to the smart multi-function storage case, the entire bundle is pleasingly robust.

Finally, Commodore: The Amiga Years. The follow-up to author Brian Bagnall’s Commodore: A Company on the Edge, The Amiga Years was officially cancelled years ago before being resurrected through a crowdfunding campaign. Since the closure of the campaign, however, the project was beset by delays and a last-minute editing decision that sees the final third of the story, taking Commodore to its sad demise, spun out into yet another book – a move backers criticising the decision have positioned as a blatant attempt at extracting more money. As with A Company on the Edge, though, the story told in The Amiga Years is one well worth the entry price – if suffering a little from Bagnall’s wandering editorial process, whereby topics raised as though you should already know them in Chapter 2 won’t be formally introduced until Chapter 5.

All this, and slightly less stuff by people who aren’t me, can be found at your nearest supermarket, newsagent, or digitally via Zinio and similar services.

HackSpace Magazine, Issue 3

HackSpace Magazine Issue 3This month’s HackSpace Magazine includes a review of an entirely unique device designed to make it possible to trade the Bitcoin cryptocurrency in-person as a physical item without any of the security risks that would normally be involved: the Coinkite Opendime.

For those unfamiliar, a primer: cryptocurrencies, including Bitcoin, work on the basis of a distributed ledger system known as the blockchain – a highly-secure database, effectively, which is shared between nodes and which cannot be faked or edited once committed. When you “have Bitcoins” in a “wallet,” what you actually have is the private key required to make transactions on the blockchain to move the coins you own from place to place.

The drawback of this approach compared to cold hard cash is that it becomes impossible to make secure off-chain transactions: you can save your keys to a flash drive, write them in an email, or even print them out and hand them to someone in person, but if you kept a copy it’s perfectly possible for you to transfer the coins to a different “wallet” out from under the recipient’s nose.

The Opendime aims to resolve this. Looking like a denuded flash drive itself, the Opendime is a smart self-contained microcomputer which performs the generation of private keys internally and locks them away – meaning it can receive Bitcoins but not spend them, until such a time as the private key is unlocked by popping a small surface-mount resistor off the board with a physical pin. In other words: if you receive an Opendime which reports it is still sealed, you are guaranteed to be the only person with access to that private key.

Sadly, since penning the relatively-positive review, I’ve encountered a major problem with the Opendime: having carried one on a keyring for a month or so, it spontaneously unsealed itself without the resistor being touched. Support from Coinkite has proven non-existent, and at £15 landed a piece with a minimum order of three units the Opendime is now an expensive but useless trinket while I find myself unable to trust the remaining two in the pack.

The review can be read in full within the magazine itself, which is available in print at all good newsagents and supermarkets and as a free digital download under the Creative Commons licence at HackSpace’s official website.

Custom PC, Issue 174

Custom PC Issue 174This month’s Hobby Tech column takes a look at a very special eight-byte – not a typo – microcomputer, walks through turning a spare Raspberry Pi into a Nav Coin-mining cryptocurrency machine, and looks forward to the launch of the ZX Spectrum Next with a look at a deep-dive book detailing the original Spectrum’s neat Ferranti Uncommitted Logic Array (ULA) chip.

First, the Mini C88. Designed by the multi-talented Daniel Bailey as a more affordable version of his C88, swapping the field-programmable gate array (FPGA) on which he implemented his own processor core design for an Arduino Zero and the extremely clever Dynamic Binary Translation (DBT) technique, the C88 is designed to be about as simple as a computer can get. Based on a custom instruction set, the C88 has just eight memory locations of eight bits apiece and is programmed by toggling each bit using a series of pleasingly tactile switches while monitoring the process on the 8×8 LED matrix that serves as its display.

For regular readers, this will all sound familiar: the original FPGA-based C88 and its 32-byte bigger brother the C3232 were the subject of an interview back in Issue 155. While Daniel has still not turned the C88 into a kit you can head out and buy, the Mini C88 is definite progress in that direction – and, as always, anyone interested in the project should hassle him about it on Twitter.

For those with a Raspberry Pi and a desire to play with cryptocurrency, meanwhile, this month’s tutorial will be of definite interest: a guide to turning a Pi into a ‘Stake Box’ for the Nav Coin cryptocurrency. Designed as an alternative to Bitcoin, Nav Coin offers those who run network nodes rewards in the form of a five percent return on their coin holdings when locked up in this manner. Taking less than an hour to set up and requiring nothing more than a low-powered computer, it’s a great way to get involved – and the Nav Coin project itself definitely one to follow.

Finally, while waiting impatiently for my ZX Spectrum Next microcomputer to land – which, I’m pleased to say, has since happened – I enjoyed a re-read of Chris Smith’s excellent The ZX Spectrum ULA: How to Design a Microcomputer. Based on interviews and deep-dive analysis, the book investigates the tricks and techniques which allowed Sinclair Computers to build the ZX Spectrum micro at such a bare-bones cost – which, in turn, was thanks to clever use of an Uncommitted Logic Array (ULA) chip from Scottish electronics giant Ferranti. Effectively a write-once version of the modern FPGA, Ferranti’s ULA saw the number of components in the ZX81 drop to a quarter compared to the ZX80 and is key to how the ZX Spectrum does what it does.

For all this, and a bunch of other interesting things by people who aren’t me, pick up a copy of Custom PC Issue 174 from your nearest supermarket, newsagent, or digitally via Zinio and similar services.

Custom PC, Issue 126

Custom PC Issue 126My monthly Custom PC column, Gareth Halfacree’s Hobby Tech, continues with a look at the toys and projects that have been entertaining me over the past four weeks including the acquisition of a core memory module, the Raspberry Pi GertDuino add-on board, and a guide – teased on the cover splash – to mining the Bitcoin cryptocurrency on said Pi.

First, the GertDuino. I won’t repeat myself with a summary of the device’s features – which are readily available in my review summary for Linux User & Developer Issue 135 – except to say that, as is usual for reviews in Hobby Tech, the review is written from a very personal perspective. As a result, the reader can enjoy a summarised version of my first few days with the device – including the heartache I had getting the blessed thing to work with the Arduino integrated development environment (IDE).

For the usual vintage computing portion of the column, I took a look at a new – to me – acquisition: a core memory module, pulled from a Soviet-era industrial computer of some description. The predecessor to modern transistor-based memory, magnetic core – literally a mesh of magnetic toroids which can be flipped to hold either a 0 or a 1 – has had an inestimable impact on modern computing, to the point where even today the process of saving memory contents to permanent storage for review is known as a ‘core dump.’

Also, the thing looks amazing under a microscope.

Finally, this month’s semi-regular tutorial section looks at using a USB-connected application specific integrated circuit (ASIC) to rapidly mine the Bitcoin cryptocurrency on a low-power Raspberry Pi. Prompted by my good friend Martyn Ranyard – the joint owner of a considerably more powerful mining rig than the one I created – the tutorial walks the reader through the exact steps I took to add Bitcoin mining facilities to my multipurpose Pi-based home server.

All this, plus a bunch of interesting stuff written by people who aren’t me, can be yours with a trip to your local supermarket, newsagent or a digital purchase on distribution services like Zinio. If you’d rather not risk missing an issue, Dennis Publishing is currently offering subscriptions at 50 per cent off the normal rate until the 31st of January.