Slide Rules Were The Original Personal Computers

November 5, 2015 by 67 Comments

Unless you are above a certain age, the only time you may have seen a slide rule (or a slip stick, as we sometimes called them) is in the movies. You might have missed it, but slide rules show up in Titanic, This Island Earth, and Apollo 13. If you are a fan of the original Star Trek, Mr. Spock was seen using Jeppesen CSG-1 and B-1 slide rules in several episodes. But there was a time that it was common to see an engineer with a stick hanging from his belt, instead of a calculator or a cell phone. A Pickett brand slide rule flew to the moon with the astronauts and a K&E made the atomic bomb possible.

Slide rules are a neat piece of math and history. They aren’t prone to destruction by EMP in the upcoming apocalypse (which may or may not include zombies). Like a lot of things in life, when it comes to slide rules bigger is definitely better, but before I tell you about the 5 foot slide rule in my collection, let’s talk about slide rules in general.
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Automatic Cat Feeder Dispenses Noms, Wants Cheezburger

November 5, 2015 by 24 Comments

[Domiflichi] likes his cats, but not the drudgery of feeding them. So, like any good engineer, this simple problem became his next project: building an automatic cat feeder. Based on an Arduino, his creation beeps to let the cats know that it is dinnertime, then dispenses food into a number of bowls. There are also buttons for manual control. This lets him give individual cats a separate feeding. Rounding out the feature set, a DS1307 RTC tracks the feeding times.

One of the most interesting parts of his build is the transfer from breadboard to protoboard. This usually involves taking apart a working version, then putting it back together and trying to figure out why it doesn’t work anymore. [Domiflichi]’s problem (detailed in a follow-up post) was figuring out how to program the real-time clock module to set the time, because it looses the time when you disconnect the power. Rather than use the Arduino to program the RTC,  he used the battery backup feature of the RTC chip, programming it on his computer and then soldering it onto the board. He went on to remove the backup battery after the chip was in place. That’s a solution that will no doubt have many readers waving their fingers disapprovingly, but it worked.

It may seem overly complicated, but his project is worth checking out to see how he approached some of the engineering challenges. The food hoppers themselves are off-the-shelf cereal dispensers. We’ve seen other designs bootstrap this mechanism with 3D printed augers.

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The IBM 1401’s Unique Qui-Binary Arithmetic

November 5, 2015 by 12 Comments

Old mainframe computers are interesting, especially to those of us who weren’t around to see them in action. We sit with old-timers and listen to their stories of the good ol’ days. They tell us about loading paper tape or giving instructions one at a time with toggle switches and LED output indicators. We hang on every word because its interesting to know how we got to this point in the tech-timeline and we appreciate the patience and insanity it must have taken to soldier on through the “good ol’ days”.

[Ken Shirriff] is making those good ol’ days come alive with a series of articles relating to his work with hardware at the Computer History Museum. His latest installment is an article describing the strange implementation of the IBM 1401’s qui-binary arithmetic. Full disclosure: It has not been confirmed that [Ken] is an “old-timer” however his article doesn’t help the argument that he isn’t.

Ken describes in thorough detail how the IBM 1401 — which was first introduced in 1959 — takes a decimal number as an input and operates on it one BCD digit at a time. Before performing the instruction the BCD number is converted to qui-binary. Qui-binary is represented by 7 bits, 5 qui bits and 2 binary bits: 0000000. The qui portion represents the largest even number contained in the BCD value and the binary portion represents a 1 if the BCD value is odd or a 0 for even. For example if the BCD number is 9 then the Q8 bit and the B1 bit are set resulting in: 1000010.

The qui-binary representation makes for easy error checking since only one qui bit should be set and only one binary bit should be set. [Ken] goes on to explain more complex arithmetic and circuitry within the IBM 1401 in his post.

If you aren’t familiar with [Ken], we covered his reverse engineering of the Sinclair Scientific Calculator, his explanation of the TL431, and of course the core memory repair that is part of his Computer History Museum work.

Thanks for the tip [bobomb].

RPiTX Turns Rasberry Pi Into Versatile Radio Transmitter

November 4, 2015 by 64 Comments

Since the discovery that some USB TV tuner dongles could be used to monitor radio waves across a huge amount of spectrum, the software-defined radio world has exploded with interest. The one limiting factor, though, has been that the dongles can only receive signals; they can’t transmit them. [Evariste Okcestbon, F5OEO] (if that is his real name! Ok c’est bon = Ok this is good) has written some software that will get you transmitting using SDR with only a Raspberry Pi and a wire.

There have been projects in the past that use a Pi to broadcast radio (PiFM), but this new software (RPiTX) takes it a couple steps further. Using just an appropriately-sized wire connected to one of the GPIO pins, the Raspberry Pi is capable of broadcasting using FM, AM, SSB, SSTV, or FSQ signals. This greatly increases the potential of this simple computer-turned-transmitter and anyone should be able to get a lot of use out of it. In the video demo below the break, [Evariste] records a wireless doorbell signal and then re-transmits it using just the Rasbperry Pi.

The RPiTX code is available on GitHub if you want to try it out. And it should go without saying that you will most likely need an amateur radio license of some sort to use most of these features, depending on your locale. If you don’t have a ham radio license yet, you don’t need one to listen if you want to get started in the world of SDR. But a ham license isn’t hard to get and at this point it shouldn’t take much convincing for you to get transmitting.

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Dealing With Fallout

November 4, 2015 by 24 Comments

In just a few short days, Fallout 4 will be released and a substantial portion of the Hackaday staff will be taking the day off. As you would expect, a lot of people with 3D printers, soldering irons, and far too much time on their hands are getting pumped for the Fallout release. Here’s a few Fallout builds we’ve found over the past few weeks:

Pip-Boys

919501417186321280The most iconic thing you’ll find in a Fallout game is the Pip-Boy, the UI for the player and a neat wrist-mounted computer (that somehow has a CRT in it, I guess) for the player’s character. Hackaday’s own [Will Sweatman] built his own Pip-Boy 3000 that’s completely functional. The build uses a 4.3 inch touch display, a 10 position rotary switch, and a bunch of 3D printed parts.

Elsewhere on Hackaday.io, [Karl] is working on a functional Pip-Boy controller for Fallout, and [cody] built one with a Raspberry Pi. Of course, if you’re super special and have two thousand dollars to blow, Bethesda released a limited-edition Pip-Boy edition of Fallout 4 that’s compatible with most cell phones.

The Not Pip-Boys

door

There’s more to Fallout than just wrist-mounted computers, and for the true aficionados, there are gigantic gear-shaped doors. [TreyHill] has a partially finished basement with a gaming room tucked behind his very own vault door. The door itself is built out of plywood and rolls along a gear rack mounted to the floor. Will it hold up to a nuclear blast? Probably not. Is it up to code? It looks cool, at least.

[Lilykill] on Thingiverse is extremely capable with a copy of solidworks and produced a bunch of 3D models from the Fallout universe that includes power armor, ray guns, more Pip-Boys, plasma grenades, and a Nuka-Cola truck.

Fallout 4 for the Apple II

Fallout 4 will be available for the PS4, Xbox One, and PC, leaving out a large contingent of retro gamers. Fear not, lovers of the 6502: there’s’ a version for the Apple II:

This tribute to both the Apple II and Fallout was made with the Outlaw Editor, an SDK for pseudo-3D game development on exceedingly old hardware. There’s actual ray casting happening in this tribute, and it works just the same as Wolfenstein 3D or the like.

One Dollar USB Sound Card Turned O-Scope

November 4, 2015 by 40 Comments

Using the inputs on a computer’s sound card is an old trick to fake a very simplistic, AC coupled, slow oscilloscope. You can get DC operation by desoldering a couple capacitors, but if the sound card is integrated into the motherboard it raises the stakes if you mess that up.

[TMSZ] has a better option, a ~1 dollar USB sound card which is easily hacked to work as a simple oscilloscope. Easily found on eBay, the 7.1 virtual channel sound card is identical in brains to a more expensive c-media model, but the layout of the PCB makes it easier to bypass the DC blocking caps. Software and DLL files to use the sound card with Miniscope v4 — a Windows GUI for oscilloscopes — are also linked, so getting set up should be fairly simple.

Now of course this is not lab-grade measurement equipment: the sampling rate is limited to 44KHz and the voltages must be in the typical “line level” range, under two volts. If you don’t mind a little extra noise, you can increase the input impedance with a single resistor. This extends the input range up to six volts, which covers most hobby and microcontroller usage.

So if you’re really in need of a scope, but only have a buck to spend, this may be just the hack for you! Those willing to shell out a hefty sum for a high-end headless oscilloscope should look onto the virtual bench.

Shoot Down Drones With Pumpkin Cannons

November 4, 2015 by 29 Comments

Are you worried about the inevitable drone invasion? Have you been waiting for a defense system that you can trust? Look no further. This video shows just how effective the system is — no smoke and mirrors. Just results.

Forget RF jamming or WiFi hacking. If those devices work at all, they’re probably only good for stopping consumer devices. If you want to be sure that a drone is taken down, you’ll need a pumpkin cannon.

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