The power supply on this particular model has a failure mode where a dying transistor can lead to 13 V on the 5 V line. This causes all the havoc one would expect on the internals of a 1970s era portable computer. This particular computer is rather rare, so instead of calling it a lost cause, our protagonist decides to replace the faulty transistor, install a proper overvoltage protection circuit, and then start the tedious hunt for which chips actually let their magic smoke out. Continue reading “Repairing A Vintage HP 9825 The Hard Way”→
Among security professionals, a “drop box” is a device that can be covertly installed at a target location and phone home over the Internet, providing a back door into what might be an otherwise secure network. We’ve seen both commercial and DIY versions of this concept, and as you might expect, one of the main goals is to make the device look as inconspicuous as possible. Which is why [Walker] is hoping to build one into a standard USB wall charger.
This project is still in the early stages, but we like what we see so far. [Walker] aims to make this a 100% free and open source device, starting from the tools he’s using to produce the CAD files all the way up to the firmware the final hardware will run. With none of the currently available single-board computers (SBCs) meeting his list of requirements, the first step is to build a miniature Linux machine that’s got enough processing power to run useful security tools locally. Obviously such a board would be of great interest to the larger hacker and maker community.
The RTL8188CUS is likely to get integrated later on.
So far, [Walker] has decided on his primary components and is working on a larger development board before really going all-in on the miniaturization process. As of right now he’s planning on using the Allwinner A33 to power the board, a sub-$10 USD chipset most commonly seen in low-cost Android tablets.
The A33 boasts a quad-core Cortex-A7 clocked at 1.2 GHz, and offers USB, I2C, and SPI interfaces for expansion. It will be paired with 1 GB of DDR3 RAM, and an SD card to hold the operating system. Naturally a device like this will need WiFi, but until [Walker] can decide on which chip to use, the plan is to just use a USB wireless adapter. The Realtek RTL8188CUS is a strong contender, as the fact that it comes in both USB and module versions should make its eventual integration seamless.
The idea is to use the Origin 2000 server as the base. These didn’t ship with any form of video output or even a keyboard and mouse interface. However, by substituting in the IO6G module from the Onyx2 machine, and SI graphics cards from the Octane, it’s possible to get graphics and input up and running. With multiple graphics cards and a few CAD DUO boards installed via a PCI adapter called the “shoebox”, there’s provisions for up to four separate monitors, keyboards and mice. With all this hardware, it’s theoretically possible for four users to login to the X server running in the IRIX OS on the Origin 2000 machine. Then, it’s a simple matter of firing up four instances of Quake and a dedicated server and you’re up and gaming.
[CelGenStudios] goes so far as exploring the limits of the supercomputer-grade hardware, suggesting that 7 players or more could be possible. Unfortunately, SGI hardware isn’t easy to come by, nor is it cheap, even decades after release — so thus far, the concept remains untested. We’d dearly love to see such a setup happen at QuakeCon or a hacker con, though, so if you pull it off, you know how to call. We note there’s a few Octane 2000s at the Jim Austin Computer Collection, so perhaps they might be the ones to achieve the feat.
In the meantime, check out a practical exploration of the concept on modern hardware with the original [Linus Tech Tips] project. The basic theory is simple – create a hugely powerful PC, with a beefy CPU, plenty of RAM, and one graphics cards for each of the seven players. They run multiple virtual machines and managed to deliver a full 7 player experience running off just one CPU.
Say what you will about office life: there were definitely some productivity perks, but the coffee is much better at home. Like many of us, [Pierre] has been working from home for the last year or so. And as much as he might enjoy spending so much time in his small Parisian apartment, it lacks many of the amenities of the office such as a scanner, printer, and, you know, a reasonable amount of space in which to work.
Inspired by another build, [Pierre] set out to build his dream desk that is maximum PC power in minimum space. It is chock full of easily-accessible cavities that hide everything you’d expect, plus a few things you don’t, like a flatbed scanner, a printer, a router, and a wireless charging pad. One cavity is dedicated to I/O, and another has three international power sockets. The only thing it doesn’t hide is the 22″ pen display that [Pierre] uses for sketching, signing documents, and occasionally as a second monitor.
A home-brew jig makes consistent dowel drilling much easier.
This desk may look like solid wood, but the top is a veneer that’s glued on to a custom-cut 1mm steel sheet. The inside frame is made of hardwood and so are the legs — one of them has a hidden channel for the only two cords that are even somewhat visible — the power and Ethernet cables. He joined all the frame pieces with dowel rods, and made a 3D-printed and metal-reinforced drilling jig to get the holes just right.
[Pierre] started this build by planning out the components and making meticulous notes about the dimensions of every piece. Then he sketched it and modelled it in FreeCAD to get all the cavities and cable runs correct and ensure good airflow through the desk. After that it was on to woodworking, metalworking, and PCB fab for relocated and hidden display controls and a custom-built amplifier.
It’s obvious that a lot of thought went in to this, and there’s a ton of work appreciate here, so clear off that inferior desk of yours and check out the build video after the break. Wish you had a PC desk? [Pierre] is seriously considering a Kickstarter if enough people show interest.
Building your own CPU is arguably the best way to truly wrap your head around how all those ones and zeros get flung around inside of a computer, but as you can probably imagine even a relatively simple processor takes an incredible amount of time and patience to put together. Plus, more often than not you’re then left with a maze of wires and perfboards that takes up half your desk and doesn’t do a whole lot more than blink some LEDs.
An early prototype of the Pineapple ONE.
But the Pineapple ONE, built by [Filip Szkandera] isn’t your average homebrew computer. Oh sure, it still took two years for him to design, debug, and assemble, his 32-bit RISC-V CPU and all its associated hardware; but the end result is a gorgeous looking machine that runs C programs and offers a basic interactive shell over VGA. In fact with its slick 3D printed enclosure, vertically stacked construction, and modular peripheral connections, it looks more like some kind of high-tech scientific instrument than a computer; homebrew or otherwise.
[Filip] says he was inspired to build this 500 kHz (yes, kilohertz) beauty using only discrete logic components by [Ben Eater]’s well known 8-bit breadboard computer and [Robert Baruch]’s LMARV-1 (Learn Me A RISC-V, version 1). He spent six months simulating the machine before he even started creating the schematics, let alone design the individual boards. He tried to keep all of his PCB’s under 100 x 100 mm to take advantage of discounts from the fabricator, which ultimately led to the decision to align the nine boards vertically and connect them together with pin headers.
In the video below you can see [Filip] start up the computer, call up a bit of system information, and even play a rudimentary game of snake before peeking and poking some of the machine’s 512 kB of RAM. It sounds like there’s still some work to be done and bugs to squash, but we’ve already seen enough to say this machine has more than earned entry into the pantheon of master-crafted homebrew computers.
It’s interesting to imagine what computers may have looked like throughout different time periods that precede their portability or even their existence altogether. In the 1950s and ’60s, computers still filled entire rooms, but if the age of the PC had arrived earlier one is left to wonder what might a minimalist mid-century PC might look like.
Well, if we were lucky, it would have looked something like [xmorneau]’s cubical computing creation. This DIY beauty is made of scrap oak and a sexy set of hairpin legs. As hot as it looks, [xmorneau] shouldn’t have to worry about overheating — the bottom is completely open except for an intake fan, there’s another fan at the top that exhausts hot air through a mesh grille, and those lovely little legs elevate it four inches off the desk. Our favorite part (after the legs) has to be the secret lid that blends in beautifully.
The cube measures 32cm³ (~12.6in³), so [xmorneau] went with a mini-ATX motherboard, but was able to fit in a full-size graphics card. Everything is mounted internally to wood except for the mobo, which is mounted on a panel of sheet metal that makes up the back wall.
We love the way this looks and are glad to see that this build changed [xmorneau]’s opinion of RGB a little bit, because we can’t help but like it both ways.
For an old CPU, finding all the valid instructions wasn’t very hard. You simply tried them all. Sure, really old CPUs might make it hard to tell what the instruction did, but once CPUs got illegal instruction traps, you could quickly just scan possible op codes and see what didn’t throw an exception. Modern processors, though, are quite another thing. For example, you might run a random instruction that locks up the machine or miss an instruction that would have been valid but the CPU is in the wrong mode. [Can Bölük] has a novel solution: By speculatively executing the target instruction and then monitoring the microcode sequencer, he can determine if the CPU is decoding an instruction even if it refuses to execute it.
Some unknown instructions may have power for good or evil, such as the recently announced undocumented instructions that can apparently rewrite the microcode. We expect to see a post soon on how to reprogram your Intel processor to run as a 6502 natively.
