8-bit Computer Made Solely From NAND Gates

As an electronics rookie, one of the first things they tell you when they teach you about logic gates is, “You can make everything from a combination of NAND gates”. There usually follows a demonstration of simple AND, OR, and XOR gates made from NAND gates, and maybe a flip-flop or two. Then you move on, when you want a logic function you use the relevant device that contains it, and the nugget of information about NAND gates recedes to become just another part of your electronics general knowledge.

Not [Alexander Shabarshin] though. He’s set himself the task of creating an entire CPU solely from NAND gates, and he’s using 74F00 chips to give a hoped-for 1MIPS performance.  His design has an 8-bit data bus but a 4-bit ALU, and an impressive 2-stage pipeline and RISC instruction set which sets it apart from the computers most of us had when 74-series logic was a much more recent innovation. So far he has completed PCBs for a D-type flip-flop and a one-bit ALU, four of which will work in parallel in the final machine

Unsurprisingly, we have maintained a keen interest in TTL computers here at Hackaday for a very long time. You might say that we have featured so many for the subject to deserve a review article of its own. There is the ASAP-3, the Magic-1, the Duo Basic, the Apollo181, the unnamed CPU made by [Donn Stewart], the BMOW, and a clone of the Apollo Guidance Computer. But what sets [Alexander’s] project aside from all these fine machines is his bare-metal NAND-only design. The other 74-series CPU designers have had the full range of devices such as the 74181 ALU at their disposal. By studying the building blocks at this most fundamental level a deeper understanding can be gained of the inner workings of parts normally represented just as black boxes.

One of the briefs for writing a Hackaday article is that if the subject makes the writer stop and read rather than skim over it then it is likely to do so for the reader too. This project may not yet have delivered a working CPU, but its progress so far is interesting enough for an in-depth read. Definitely one to watch.

Nixie Thermometer Destined For Custom PC Case

There’s no denying the retro appeal of the warm glow of a set of Nixies, and when a friend was looking for a unique touch for the case of his new liquid-cooled PC, [Luca] pitched in with this sweet Nixie thermometer.

From the look of [Luca]’s detailed blog entries, he’s been at this build since the New Year. He starts with a list of requirements, including the oddly specific need for a round PC board. For the thermometer, three Nixies are enlisted for the display, two for the temperature and one for the units. Everything was prototyped on perf board before committing to a PCB design, but even with careful planning, the Nixie sockets on the final PCB came out a tiny bit too close together. Luckily the tubes still fit, even if they are snuggled together some. And yes, the tube bases all include the hated RGB LEDs – hey, it’s what the customer wanted. The specs are for the colors to change at the touch of a button; we’d like to see a color gradient linked to the temperature – blue for “nice and cool”, red for “leave the room.” You can see the finished thermometer in action below the break.

The recent run of Nixie projects continues unabated, and this one has a nice look that’s sure to complement the finished case. We’ve asked [Luca] to keep us up-to-date on the project, so hopefully we’ll get a look at why a round PCB is needed. While we wait for that, check out an earlier Nixie thermometer build with a bar graph twist.

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Barcodes That Hack Devices

[virustracker] has been playing around with barcodes lately, and trying to use them as a vector to gain control of the system that’s reading them. It’s a promising attack — nobody expects a takeover via barcodes. The idea isn’t new, and in fact we’ve seen people trying to drop SQL attacks in barcodes long ago, but [virustracker] put a few different pieces together and came up with a viable attack.

The trick is that many POS terminals and barcode readers support command characters in their programming modes. Through use of these Advanced Data Formatting (ADF) modes, [virustracker] sends Windows-Key-r, and then cmd.exe, ftps a file down, and runs it. Whatever computer is on the other side of the barcode scanner has just been owned. ADF even supports a delay function to allow time for the command window to pop up before running the rest of the input.

The article details how they got their payload from requiring more than ten individual barcodes down to four. Still, it’s a suspicious-looking attack to try to pull off where other people (think cashiers) are looking. However, we have many automated machines in our everyday life that use barcodes. How many of these are vulnerable is an open question. [virustracker] suggests lottery machines, package-delivery automats, and even hospitals.

The defense is simple, and it’s the same as everywhere else: disable the debug and configuration modes in your production systems, and sanitize your input. Yes, even the barcodes.

Lego Gaming Computer Case

Lego isn’t the first material that springs to mind when you think about building a new gaming computer case, but it does make sense when you think about it. It is easy to work with, can be easily reconfigured, and it’s pretty cheap. That’s the idea behind this very cool (no pun intended) gaming computer case build by [Mike Schropp]. Built around a Skylake i7 CPU and an NVidia 980 Ti graphics card, his build has an unusual X-shaped design that allows for plenty of airflow. The sides of the X hold the CPU cooler, the power supply, the hard drives and the graphics card cooler, so each of them has its own separate flow of cool air from the outside. That avoids the common problem of hot air from one component being passed over another, so it doesn’t get cooled properly. Critically for a gaming system, this design keeps all of the components much cooler than a more traditional case, which makes for more overclocking potential.

At the moment, [Mike] says he is struggling to keep up with the demand for people who want to buy custom versions of his build, but he is planning to release the details soon. “Initially that will probably be in the form of a DIY kit, where you can buy the plans with all the Lego bricks needed for the build, in a kit form” he told us. “Then you can add your own computer components to complete your build. At some point I’ll probably also just offer the plans themselves and allow the end-user to acquire the Lego bricks needed.”

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Calculator Built In Super Mario Level. Mamma Mia!

Most people use the Super Mario Maker to, well, create Super Mario game levels. [Robin T] decided to try something a little different: building a working calculator. Several hundred hours later, he created the Cluttered Chaos Calculator, which definitely lives up to the name. What this Super Mario level contains is a 3-bit digital computer which can add two numbers between 0 and 7, all built from the various parts that the game offers. To use it, the player enters two numbers by jumping up in a grid, then they sit back and enjoy the ride as Mario is carried through the process, until it finally spits out the answer in a segment display.

It’s not going to be winning any supercomputer prizes, as it takes about two minutes to add the two digits. But it is still an incredibly impressive build, and shows what a dedicated hacker can do with a few simple tools and a spiny shell or two.

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Thermaltake Gets On The 3D Printing Bandwagon

We’re interested by a move from Thermaltake, a manufacturer of computer cases, fans, and power supplies. Thermaltake has released a computer case designed to be modded by those with a 3D printer. They released a set of models that fits the new case. These are all hosted on a service much like Thingiverse. So if you want a single SSD or a whole rack, print the model. Watercooling? There’s a model for that. In concept, it’s very cool.

We’re not certain how to feel about this. Our initial impression was that if Thermaltake is going to launch a case around 3D printing, they should at lease tune their printer and get some nice prints before they take the press photos. On our second pass we became intrigued. Is this a manufacturer cutting costs, crowd-sourcing design and engineering talent for free, or empowering the user? Arguably, a computer case is a great test bed for this kind of interaction.

Despite out skepticism, we’d like to see more manufacturers take this kind of contributing interest in 3d printing. If only to see where it goes. What other products do you think would benefit from this kind of, print the product you actually want model?

Balancing D-Pad Gets You In The Game

Inspired by TRON, [lasttraveler] decided to try his hand at building a Balance Board — basically a giant joystick pad you can stand on to control.

Constructed of solid wood, the switches are actually very simple — he’s just using tin foil to make the contacts. By opening up the sacrificial keyboard, he’s taken the up/down/left/right keys and wired the contacts directly to the four tin foil pads. A recess in the bottom of the board allows the rest of the keyboard to remain intact — in case he ever wants to take it apart again. Or add new buttons!

Wooden crossbeams in the shape of an X allow the board to balance in the middle without touching any of the contacts — but as soon as you lean the connections are made and you’re off to the races!

Now strap on a VR headset and play some TRON! Though if you want even more accurate control you might want to pick up a cheap Wii balance board instead.

[via r/DIY]