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If you were a school-age child in the 1980’s or 1990’s, you almost certainly played The Oregon Trail. Thanks to its vaguely educational nature, it was a staple of school computers until the early 2000’s, creating generations of fans. Now that those fans are old enough to have disposable incomes, we are naturally seeing a resurgence of The Oregon Trail merchandise to capitalize on one of humanity’s greatest weaknesses: nostalgia.
Enter the Target-exclusive The Oregon Trail handheld game. Priced at $24.99 USD and designed to look like the classic beige-box computers that everyone of a certain age remembers from “Computer Class”, it allows you to experience all the thrills of dying from dysentery on the go. Naturally there have been versions of the game for mobile devices in the past, but how is that going to help you when you want to make your peers at the coffee shop jealous?
But we’re not here to pass judgement on those who hold a special place for The Oregon Trail in their hearts. Surely, there’s worse things you could geek-out on than interactive early American history. No, you’re reading this post because somebody has put out a handheld PC-looking game system, complete with a simplified keyboard and you want to know what’s inside it. If there was ever a cheap game system that was begging to be infused with a Raspberry Pi and some retro PC games, this thing is it. Continue reading “Teardown: The Oregon Trail Handheld”→
Today is March 14th, or Pi Day because 3.14 is March 14th rendered in month.day date format. A very slightly better way to celebrate the ratio of a circle’s circumference to its diameter is July 22nd, or 22/7 written in day/month order, a fractional approximation of pi that’s been used for thousands of years and is a better fit than 3.14. Celebrating Pi Day on July 22nd also has the advantage of eschewing middle-endian date formatting.
But Pi Day is completely wrong. We should be celebrating Tau Day, to celebrate the ratio of the circumference to the radius instead of the diameter. That’s June 28th, or 6.283185…. Nonetheless, today is Pi Day and in the absence of something truly new and insightful — we’re still waiting for someone to implement a spigot algorithm in 6502 assembly, by the way — this is a fantastic opportunity to discuss something tangentially related to pi, the history of mathematics, and the idea that human knowledge builds upon itself in an immense genealogy stretching back to the beginning of history.
This is our Pi Day article, but instead of complaining about date formats, or Tau, we’re going to do something different. This is how you approximate pi with the Monte Carlo method, and how anyone who can count to a million can get a better approximation of one the fundamental constants of the Universe than Archimedes.
While the Raspberry Pi’s birthday (and the traditional release date for the newest and best Pi) was a few weeks ago, Pi Day is a fitting enough date for the introduction of the best Pi to date. The Raspberry Pi 3 Model B+ is the latest from the Raspberry Pi foundation. It’s faster, it has better networking, and most interestingly, the Pi 3 Model B+ comes with modular compliance certification, allowing anyone to put the Pi into a product with vastly reduced compliance testing.
It’s fair to say that software-defined radio represents the most significant advance in affordable radio equipment that we have seen over the last decade or so. Moving signal processing from purpose-built analogue hardware into the realm of software has opened up so many exciting possibilities in terms of what can be done both with more traditional modes of radio communication and with newer ones made possible only by the new technology.
It’s also fair to say that radio enthusiasts seeking a high-performance SDR would also have to be prepared with a hefty bank balance, as some of the components required to deliver software defined radios have been rather expensive. Thus the budget end of the market has been the preserve of radios using the limited baseband bandwidth of an existing analogue interface such as a computer sound card, or of happy accidents in driver hacking such as the discovery that the cheap and now-ubiquitous RTL2832 chipset digital TV receivers could function as an SDR receiver. Transmitting has been, and still is, more expensive.
The LimeSDR Mini’s chunky USB stick form factor.
A new generation of budget SDRs, as typified by today’s subject the LimeSDR Mini, have brought down the price of transmitting. This is the latest addition to the LimeSDR range of products, an SDR transceiver and FPGA development board in a USB stick format that uses the same Lime Microsystems LMS7002M at its heart as the existing LimeSDR USB, but with a lower specification. Chief among the changes are that there is only one receive and one transmit channel to the USB’s two each, the bandwidth of 30.72 MHz is halved, and the lower-end frequency range jumps from 100 kHz to 10 MHz. The most interesting lower figure associated with the Mini though is its price, with the early birds snapping it up for $99 — half that of its predecessor. (It’s now available on Kickstarter for $139.)
There’s a sinking feeling when a firmware upgrade to a piece of equipment goes wrong. We’ve all likely had this happen and bricked a device or two. If we are lucky we can simply reapply the upgrade or revert to a previous version, and if we’re unlucky we have to dive into a serial debug port to save the device from the junk pile. But what happens when both those routes fail? If you are [Arko], you reverse-engineer the device and write your own bootloader for it.
The offending bricked object was a Monoprice MP Mini Delta 3D printer to which he was foolhardy enough to apply new firmware after seeing a friend’s machine taking it without issue. Finding the relevant debug interface on its main PCB he applied the firmware upgrade again, only to realise that in doing so he had overwritten its bootloader. The machine seemed doomed, but he wasn’t ready to give up.
What follows in his write-up is a detailed examination of the boot mechanism and memory map of an ARM Cortex M0 processor as found in the Monoprice’s STM32F070CB. We learn about vector tables for mapping important addresses of interrupts and execution points, and the mechanics of a bootloader in setting up the application it launches. This section is well worth a read on its own, even for those with no interest in bricked 3D printers.
In the end he had a working bootloader to which he appended the application firmware, but sadly when he powered up the printer there was still no joy. The problem was traced to the serial connection between the ARM doing the printer’s business and the ESP8266 running its display. After a brainstorm suggestion with a friend, a piece of code was found which would set the relevant registers to allow it to run at the correct speed.
So after a lot of work that resulted in this fascinating write-up, there was a working 3D printer. He suggests that mere mortals try asking Monoprice for a replacement model if it happens to their printers, but we’re extremely glad he persevered. Without it we would never have had this fascinating write-up, and would be the poorer without the learning experience.
We often see people funneling their passion into keeping beloved devices in operation long past their manufacturer’s intent. These replacement Thinkpad motherboards (translated) bring old (yet beloved) Thinkpads a much desired processor upgrade. This is the work of the user [HOPE] on the enthusiast forum 51nb. The hack exemplifies what happens when that passion for legendary gear hits deep electrical expertise and available manufacturing. This isn’t your regular laptop refurbishment, [HOPE] is building something new.
ThinkPads are known for their zealous following (as our own [Brian Benchoff] underscored last year). Lenovo has steered the venerable brand into the future while the laptop market has drifted deeper and deeper into the wilds of tight integration at the expense of user modification. Along the way 4:3 screens were traded for media-friendly 16:9, TrackPoints were traded for trackpads, and the classic ThinkLight gave way to real keyboard backlights. These progressions left a shrinking but vocal group of old school Thinkpad enthusiasts — the cult of Thinkpad — clinging to beloved devices like 2007’s X61 and T60 ignored by a changing market.
In an astounding turn of ingenuity [HOPE] has revitalized these classic ThinkPads by entirely replacing their motherboards. And not just for one particular model, there are options available for at least 3 families of computers. The new devices are referred to by model numbers never used by IBM or Lenovo; the X60/61 motherboard makes an X62, the X200/201 motherboard makes an X210, and the T60 motherboard makes a T70. Depending on the customer’s preference either a bare motherboard or a fully assembled unit is available.
Classic stickers with non-classic ports
Depending on the exact model in question these motherboards slot directly into the original chassis but add recent generation Intel Core I processors, DDR4, USB 3.0/3.1, Thunderbolt 3 and more. Often they reuse the original heat sinks and fans, and expose these ports through the same chassis apertures the original motherboards used. Considering these machines are a decade older than the hardware being crammed inside them the level of integration is truly impressive. The end result looks like it could have come out of a Lenovo factory just before Spring Festival. If you look closely at the image at the top of this article, you might notice they even included an improved “Intel Inside” sticker on the palm rest and a model number label at the lower left of the display!
There is an implicit economic statement here that’s worth calling out. A motherboard for anything more significant than a basic microcontroller is an incredibly complicated piece of technology. When the bar is moved from “small ARM processor” up to “modern x86 system” this counts extra. Not only are they complex electrically but the fabrication processes required to physically create them are at the edge of what you’d find at your favorite cheap PCB fab house. We’re talking CPUs studded with about 1100 pins, DDR4 and PCI-E with extremely tight electrical timing requirements driving elaborate board layouts, and a plethora of off-board peripheral parts. On top of those constraints the board itself must be small enough to fit inside, not a purpose-built enclosure, but an existing laptop body with whatever combination of mounting brackets and connector placements Lenovo decided on. That a hobbyist (we assume) can make their own devices in this range to sell for $500-$700 is nothing short of astounding.
Fresh replacements being installed
This shouldn’t be possible. More accurately, it’s likely possible because there are other drivers which make the cost of PCB fabrication and assembly lower and more accessible than ever. The general march of technology certainly, but perhaps the presence of mobile devices and a desire to repair and improve them. After all and if the rumors are to be believed, anyone who can find the right Huaqiangbei stall can get the NAND replaced in their iPhone, a once complex process made simple.
It’s difficult to track the progression of each model as they are primarily covered on the 51nb forums (a Facebook page called [Lcdfans] makes some of the information available in English). However it’s possible to find hands-on information like [koobear]’s review on Reddit.
