Discrete Transistor Computer Is Not Discreet

June 23, 2015 by 51 Comments

Every few years, we hear about someone building a computer from first principles. This doesn’t mean getting a 6502 or Z80, wiring it up, and running BASIC. I’m talking about builds from the ground up, starting with logic chips or even just transistors.

[James Newman]’s 16-bit CPU built from transistors is something he’s been working on for a little under a year now, and it’s shaping up to be one of the most impressive computer builds since the days of Cray and Control Data Corporation.

The 10,000 foot view of this computer is a machine with a 16-bit data bus, a 16-bit address bus, all built out of individual circuit boards containing single OR, AND, XOR gates, decoders, multiplexers, and registers.  These modules are laid out on 2×1.5 meter frames, each of them containing a schematic of the computer printed out with a plotter. The individual circuit modules sit right on top of this schematic, and if you have enough time on your hands, you can trace out every signal in this computer.

The architecture of the computer is more or less the same as any 16-bit processor. Three are four general purpose registers, a 16 bit program counter, a stack pointer, and a status register. [James] already has an assembler and simulator, and the instruction set is more or less what you would expect from a basic microprocessor, although this thing does have division and multiplication instructions.

The first three ‘frames’ of this computer, containing the general purpose registers, the state and status registers, and the ALU, are already complete. Those circuits are mounted on towering frames made of aluminum extrusion. [James] already has 32 bytes of memory wired up, with each individual bit having its own LED. This RAM display will be used for the Game of Life simulation once everything is working.

While this build may seem utterly impractical, it’s not too different from a few notable and historical computers. The fastest computer in the world from 1964 to ’69 was built from individual transistors, and had even wider busses and more registers. The CDC6600 was capable of running at around 10MHz, many times faster than the estimated maximum speed of [James]’ computer – 25kHz. Still, building a computer on this scale is an amazing accomplishment, and something we can’t wait to see running the Game of Life.

Thanks [aleksclark], [Michael], and [wulfman] for sending this in.

Remove Security Issues From Untrusted USB Connections

June 23, 2015 by 30 Comments

USB has become pretty “universal” nowadays, handling everything from high-speed data transfer to charging phones. There are even USB-powered lava lamps. This ubiquity doesn’t come without some costs, though. There have been many attacks on smartphones and computers which exploit the fact that USB is found pretty much everywhere, and if you want to avoid these attacks you can either give up using USB or do what [Jason] did and block the data lines on the USB port.

USB typically uses four wires: two for power and two for data. If you simply disconnect the data lines, though, the peripheral can’t negotiate with the host for more power and will limp along at 0.5 watts. However, [Jason] discovered that this negotiation takes place at a much lower data rate than normal data transfer, and was able to put a type of filter in between the host and the peripheral. The filter allows the low-frequency data transfer pass through but when a high-frequency data transfer occurs the filter blocks the communication.

[Jason] now has a device that can allow his peripherals to charge at the increased rate without having to worry about untrusted USB ports (at an airport or coffee shop, for example). This simple device could stop things like BadUSB from doing their dirty work, although whether or not it could stop something this nasty is still up in the air.

Retrotechtacular: Don’t Balk At Pitch-Up In The McDonnell F-101 Voodoo

June 23, 2015 by 17 Comments

The McDonnell aircraft corporation’s F-101 Voodoo was a lean, mean, supersonic machine capable of going from tarmac to 40,000 feet in about two minutes. But for all its innovation and engineering, the Voodoo had a common problem of pitch-up. That is, the swept-back wings of the Voodoo created a tendency for the plane to nose upward very sharply, negating the pilot’s control.

McDonnell assures Voodoo pilots that this problem is easily overcome with a cool head and a solid foundation of know-how about the issue. This training film is meant to provide that foundation, exploring the causes of pitch-up and the prescribed methods for recovery with and without deployment of the drag chute.

The drag chute is always the recommended route to help correct the craft. This is especially true for a full-scale pitch-up situation. Recovery is possible without the drag chute, however. The altitude lost in recovery is proportional to the altitude at the time that pitch-up occurs. That is, the lower the altitude of the craft when pitch-up occurs, the less altitude is lost in getting back to straight and level flight.

Continue reading “Retrotechtacular: Don’t Balk At Pitch-Up In The McDonnell F-101 Voodoo” →

drone racers

The Shady World Of Drone Racing

June 23, 2015 by 57 Comments

No one noticed the two men in the alley as the darkness of midnight approached – their long, black trench coats acting like a soldier’s camouflage.

“You got the goods?”

“Yeah, these are hot man…super fast..check this…”

The bark of a police siren broke their whispered conversation like a shattering glass, causing the two men to briefly freeze in their steps.

“Johnny B. got busted last week…did you hear?”

“No way man! What he get busted for?”

“Drone racing man…drone racing.”

Deep within the shadows of abandoned warehouses and dilapidated factories on the outskirts of Australian suburbia, the telltale buzz of numerous drones can be heard. Zipping to and fro at speeds upwards of 60km/h, these drones are not just flying. They’re racing each other. The operators use specialized FPV goggles that allow them to see the raceway in real time. This method, unfortunately, puts them on the wrong side of the law.

The dated laws governing drones in Australia are similar to those in the US, which were written for the radio controlled plane industry. While they technically forbid any flying outside of line-of-site, the Australian Civil Aviation Authority seems to be OK with the drone racing so long as it’s done indoors and poses no risk to people or property.

Know of any drone racing in your country? Is it legal? Do people do it anyway? Let us know in the comments.

Down Draft table

Down-Draft Table Keeps The Shop Dust Free

June 23, 2015 by 17 Comments

Wood working is great but it can certainly get the shop dusty. [BigD] is a wood worker and needed a way to keep his shop from getting super dusty while sanding or routing. He ended up making a pretty slick dual-use downdraft table with a hidden filtration system.

The table’s frame is made from standard 2-by dimensional lumber you’d likely see most shop tables made from. It was built so that the top of the table would be flush with the table of the table saw. This allows the down-draft table to also act as an out feed support for the table saw, making it easier to cut longer pieces of wood.

To allow airflow to pull any generated dust down, a plethora of holes were drilled in the table top. Down below are a couple sealed chambers, one for the incoming dust and one for the air blower that creates the down-draft air flow. The two chambers are separated by a pair of filters which keep the dust from being blown back into the shop. A little door on the side of the table allows access to clean out the accumulated dust and debris. Now [BigD] can sand up a storm on his down-draft table without breathing in a sapling worth of dust.

Really, Really Retro Computer On An FPGA

June 23, 2015 by 10 Comments

[Daniel Bailey] built himself a scaled-down clone of a very early computer in an FPGA. Specifically, he wrote some VHDL code to describe the machine in question, a scaled-down clone of the Manchester Small-Scale Experimental Machine with an 8-bit processor and a whopping 8 bytes of RAM, all of which are displayed on an LED screen. Too cool.

That he can get it to do anything at all with such constraints amazes us. Watch him program it and put it through its paces in the video below the break.

Continue reading “Really, Really Retro Computer On An FPGA” →

Hackaday Prize Entry: A Medical Tricorder

June 22, 2015 by 34 Comments

We have padds, fusion power plants are less than 50 years away, and we’re working on impulse drives. We’re all working very hard to make the Star Trek galaxy a reality, but there’s one thing missing: medical tricorders. [M. Bindhammer] is working on such a device for his entry for the Hackaday Prize, and he’s doing this in a way that isn’t just a bunch of pulse oximeters and gas sensors. He’s putting intelligence in his medical tricorder to diagnose patients.

In addition to syringes, sensors, and electronics, a lot of [M. Bindhammer]’s work revolves around diagnosing illness according to symptoms. Despite how cool sensors and electronics are, the diagnostic capabilities of the Medical Tricorder is really the most interesting application of technology here. Back in the 60s and 70s, a lot of artificial intelligence work went into expert systems, and the medical applications of this very rudimentary form of AI. There’s a reason ER docs don’t use expert systems to diagnose illness; the computers were too good at it and MDs have egos. Dozens of studies have shown a well-designed expert system is more accurate at making a diagnosis than a doctor.

While the bulk of the diagnostic capabilities rely on math, stats, and other extraordinarily non-visual stuff, he’s also doing a lot of work on hardware. There’s a spectrophotometer and an impeccably well designed micro reaction chamber. This is hardcore stuff, and we can’t wait to see the finished product.

As an aside, see how [M. Bindhammer]’s project has a lot of neat LaTeX equations? You’re welcome.

The 2015 Hackaday Prize is sponsored by: