Minimal USB Device Connects With Just A Couple Of Resistors

May 9, 2023 by Dan Maloney 10 Comments

If you’re like most of us, your basic approach to building something boils down to: “What’s the minimum amount I need to do to get this to work?” It’s not a bad strategy in general, but the minimal build is rarely enough to meet all the requirements, as this extremely minimal but functional USB device illustrates.

Functional, yes, but as [TM] explains, only if you define functional as being recognized by your operating system. The BOM for that job turns out to be really small — a 3.3-volt regulator, its capacitor, and a pair of resistors connected to a DIP switch. The resistors, 1.5k each, are connected to the D+ and D- lines of the USB connector and pull their respective lines up to 3V3 when their switch is closed. If the D- switch is thrown, it indicates a low-speed connection is requested, while D+ requests a speedier connection. Either way, its enough to get the familiar “USB connect” sound in Windows, and to see it listed in Device Manager or dmesg on Linux.

With no microcontroller to return a device descriptor, not much else happens, of course, but it’s still interesting that so little is needed to at least get the host machine to know that something was plugged in. And that alone has some diagnostic value; as [TM] points out, you could use this circuit to test that the physical port on the host at least minimally works.

He runs through a few other potentially useful scenarios, but really, the best use of something like this is to educate yourself on the lowest levels of USB connection negotiation. If you want to dive deeper into USB-C specifically, we suggest you check out [Arya Voronova]’s “All About USB-C” series.

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Can You Use A POST Card With A Modern BIOS?

May 8, 2023 by Dave Rowntree 36 Comments

[Alessandro Carminati] spends the day hacking Linux kernels, and to such an end needed a decent compilation machine to chew through the builds. One day, this machine refused to boot leaving some head-scratching to do, and remembering the motherboard diagnostics procedures of old, realized that wasn’t going to work for this modern board. You see, older ISA-based systems were much simpler, with diagnostic POST codes accessible by sniffing the bus with an appropriate card inserted, but the modern motherboard doesn’t even export the same bus anymore.

See “out 0x80, al” in there? That’s a POST code being written

Do modern machines even run a POST test at all, or are there other standards? After firing up a Linux machine and dumping the first meg of memory address space, it clearly contained some of the BIOS code. [Alessandro] looked at a disassembly of the BIOS update image and saw a similar structure, with POST code data sent to port 0x80 just like machines of old.

But instead of an ISA CPU bus, we have the Low Pin Count (LPC) bus which is used to hook up the ‘super IO’ functions, controlling things such as fans, temp sensors, and other system management functions. It also serves as the connection for the TPM feature, which usually appears as one of the motherboard connectors intended to be user-accessible. It turns out that POST codes can be accessed from this point with an appropriate POST card that can talk LPC.

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A History Of NASA Supercomputers, Among Others

May 5, 2023 by Dave Rowntree 8 Comments

The History Guy on YouTube has posted an interesting video on the history of the supercomputer, with a specific focus on their use by NASA for the implementation of computational fluid dynamics (CFD) models of aeronautical assemblies.

The aero designers of the day were quickly finding out the limitations of the wind tunnel testing approach, especially for so-called transonic flow conditions. This occurs when an object moving through a fluid (like air can be modeled) produces regions of supersonic flow mixed in with subsonic flow and makes for additional drag scenarios. This severely impacts aircraft performance. Not accounting for these effects is not an option, hence the great industry interest in CFD modeling. But the equations for which (usually based around the Navier-Stokes system) are non-linear, and extremely computationally intensive.

Obviously, a certain Mr. Cray is a prominent player in this story, who, as the story goes, exhausted the financial tolerance of his employer, CDC, and subsequently formed Cray Research Inc, and the rest is (an interesting) history. Many Cray machines were instrumental in the development of the space program, and now adorn computing museums the world over. You simply haven’t lived until you’ve sipped your weak lemon drink whilst sitting on the ‘bench’ around an early Cray machine.

You see, supercomputers are a different beast from those machines mere mortals have access to, or at least the earlier ones were. The focus is on pure performance, ideally for floating-point computation, with cost far less of a concern, than getting to the next computational milestone. The Cray-1 for example, is a 64-bit machine capable of 80 MIPS scalar performance (whilst eating over 100 kW of juice), and some very limited parallel processing ability.

While this was immensely faster than anything else available at the time, the modern approach to supercomputing is less about fancy processor design and more about the massive use of parallelism of existing chips with lots of local fast storage mixed in. Every hacker out there should experience these old machines if they can, because the tricks they used and the lengths the designers went to get squeeze out every ounce of processing grunt, can be a real eye-opener.

Want to see what happens when you really push out the boat and use the whole wafer for parallel computation? Checkout the Cerberus. If your needs are somewhat less, but dabbling in parallel computing gets you all pumped, you could build a small array out of Pine64s. Finally, the story wouldn’t be complete without talking about the life and sad early demise of Seymour Cray.
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Jet Engine Tachometer Turned Into Unique CPU Utilization Meter

May 4, 2023 by Dan Maloney 16 Comments

When you’ve got a piece of interesting old aviation hardware on your desk, what do you do with it? If you’re not willing to relegate it to paperweight status, your only real choice is to tear it down to see what makes it tick. And if you’re lucky, you’ll be able to put it to work based on what you learned.

That’s what happened when [Glen Akins] came across a tachometer for a jet airplane, which he promptly turned into a unique CPU utilization gauge for his computer. Much of the write-up is concerned with probing the instrument’s innards to learn its secrets, although it was clear from the outset that his tachometer, from Kollsman Instruments, was electrically driven. [Glen]’s investigation revealed a 3-phase synchronous motor inside the tach. The motor drives a permanent magnet, which spins inside a copper cup attached to the needle on the tach’s face. Eddy currents induced in the cup by the spinning magnet create a torque that turns the needle against the force of a hairspring. Pretty simple — but how to put the instrument to work?

[Glen]’s solution was to build what amounts to a variable frequency drive (VFD). His power supply is based on techniques he used to explore aircraft synchros, which we covered a while back. The drive uses a trio of MCP4802 8-bit DACs to generate three phase-shifted sine waves via direct digital synthesis with an RP2040. The 3-phase signal drives the motor and spins the dial, with 84-Hz corresponding to full-scale deflection.

The video below shows the resulting CPU utilization gauge — which just queries for the current load level and sends it to the RP2040 over serial — in action. It’s not exactly responsive to rapid changes, but that’s to be expected from a mechanical system. And compared to exploring such a nice instrument, it really doesn’t matter.

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Getting The Most From Fading ThinkPads

April 21, 2023 by Bryan Cockfield 40 Comments

The ThinkPad line of laptops has been widely prized not only by businesses but also by those who appreciate a high standard of hardware quality and repairability. But some think the cracks are starting to form in their reputation, as it seems that new ThinkPads are sacrificing quality for aesthetics and cost. As a result a huge modding scene has popped up around models that are a few years old like [Cal] found out when working on this X230.

At first he only made some cosmetic improvements to the laptop like replacing the worn palm rest, but quickly found himself in a rabbit hole with other upgrades like swapping out the keyboard and battery. The new keyboard is a 7-row X220 keyboard, which required modification of the connector and flashing the embedded controller with a hacked image to change the keyboard map without needing to make changes at the OS level. From there, he decided to replace the lackluster screen with a 1920×1080 matte IPS panel using an adapter board from Nitrocaster, and finished off his upgrades with a customized Coreboot BIOS for improved performance and security.

While Coreboot doesn’t remove all of the binary blobs that a bootloader like libreboot does, the latter is not compatible with more modern machines like this X230. Still, you’ll get many benefits from using Coreboot instead of the stock bootloader. For running Linux on a daily driver laptop, we appreciate all of these updates and expect that [Cal] will get plenty of years of use out of his machine. We’ve definitely seen an active modding scene for ThinkPads that were (at the time) seven years old and still going strong, so we’d expect nothing less for this one.

A New Commodore C128 Cartridge

April 17, 2023 by Bil Herd 18 Comments

A new Commodore C128 cartridge in 2023? That’s what [idun-projects] set out to do and, as you can see in the video below, did. I did the original C128 hardware design and worked with the amazing team that turned this home computer out in 1985. Honestly, I am amazed that any of them are still working 38 years later, let alone that someone is making new cartridges for it.

I also never thought I would hear about someone’s in-depth experience designing for the ‘128. The post takes us through [idun-project’s] decision to use the ‘128 and how modern expectations apply to all computers, even the old ones. Hot on the list was connectivity and reasonable storage (looking at you, floppy disks).

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Disabling Intel’s Backdoors On Modern Laptops

April 12, 2023 by Bryan Cockfield 32 Comments

Despite some companies making strides with ARM, for the most part, the desktop and laptop space is still dominated by x86 machines. For all their advantages, they have a glaring flaw for anyone concerned with privacy or security in the form of a hardware backdoor that can access virtually any part of the computer even with the power off. AMD calls their system the Platform Security Processor (PSP) and Intel’s is known as the Intel Management Engine (IME).

To fully disable these co-processors a computer from before 2008 is required, but if you need more modern hardware than that which still respects your privacy and security concerns you’ll need to either buy an ARM device, or disable the IME like NovaCustom has managed to do with their NS51 series laptop.

NovaCustom specializes in building custom laptops with customizations for various components and specifications to fit their needs, including options for the CPU, GPU, RAM, storage, keyboard layout, and other considerations. They favor Coreboot as a bootloader which already goes a long way to eliminating proprietary closed-source software at a fundamental level, but not all Coreboot machines have the IME completely disabled. There are two ways to do this, the HECI method which is better than nothing but not fully trusted, and the HAP bit, which completely disables the IME. NovaCustom is using the HAP bit approach to disable the IME, meaning that although it’s not completely eliminated from the computer, it is turned off in a way that’s at least good enough for computers that the NSA uses.

There are a lot of new computer manufacturers building conscientious hardware nowadays, but (with the notable exception of System76) the IME and PSP seem to be largely ignored by most computing companies we’d otherwise expect to care about an option like this. It’s certainly still an area of concern considering how much power the IME and PSP are given over their host computers, and we have seen even mainline manufacturers sometimes offer systems with the IME disabled. The only other options to solve this problem are based around specific motherboards for 8th and 9th generation Intel desktops, or you can go way back to hardware from 2008 and install libreboot to eliminate, rather than disable, the IME.

Thanks to [Maik] for the tip!