DIY Computer — 1968 Style

What does it mean to “build your own computer?” Today, it is likely to mean you bought a motherboard, a power supply, and a case and put it all together. You might even have made an embedded computer using a few chips, including an off the shelf CPU. However, there are those guys (like me) who have built entire computers using FPGAs and some (not like me) who have built computers out of TTL chips, discrete components, and even relays and we have covered quite a few of them.

It hasn’t always been that easy. Components are readily available now and relatively cheap (especially considering inflation). In the 1960’s, simple components cost more than you pay for them today and back then your hypothetical self was making less money. In just about every way imaginable, the cost was prohibitive.

clipSo what did you do if you were a kid saving money from a paper route in 1968 and you wanted to build a computer? Maybe you turned to How to Build a Working Digital Computer a book published in 1968 by [Edward Alcosser], [James Phillips], and [Allen Wolk]. This book did as the title promised: you could build a working digital computer. The components, though, were paper clips, tin cans, thread spools, and other household items. The only real electronic components you had to use were light bulbs and a battery, although you might also use store-bought switches in some places instead of the homemade versions shown in the book.

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Smart Sumo Seeks Central Security

[David] over at Pololu programmed a mini-sumo robot, Zumo Red, with some extra smarts.

The basic rules of sumo robotics is exactly like human sumo – push your competitor out of the ring. [David]’s robot is special because it not only detects the competition border but measures the robot’s angle to the perimeter circle. Knowing the angle, [David]’s robot can turn and run for the center of the arena, the safest location. Once safe it can attack competitors from a symbolic high-ground. Unfortunately, the robot was a light weight in an already low weight class competition. It failed to push any competitors out of the ring and did not fare well in face-to-face battles. 0J6807.550

[David]’s bot uses a three LED line sensor, pretty common today for line following, to detect the boundary. As the ‘bot is moving an outer sensor will detect the border. It continues to drive forward until the middle sensor gets a hit. That provides the measurements need to calculate the angle. Neat and simple! Knowing the angle, the robot scoots to the center to plan its next attack.

[David’s] made the code for his bot’s brain, an Arduino compatible ATmega32U4, available so it will be interesting to see if the competition picks up on this trick.

Zumo Red meets Sumo Necko and a few more competitors in the video after the break.

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Why Starting a Kickstarter Could Kick Your Butt

So you’ve come up with a great idea and now you’re thinking about starting a crowdfunding campaign – and why not, all the cool kids are doing it. Now, let’s say you already have a working prototype, or maybe you even built a small run for friends online. You’ve made 10 here, or 20 there. Sure it took some time, but making 1000, or 10,000 would be so much easier once you get all the orders in, right? Wrong.

Before you even think of setting up something like a Kickstarter, we would like to invite you to have a seat and watch this series of videos covering the things many people don’t know about manufacturing. It’s going to cost you 7 hours of sofa time, but if you’re serious about getting something to production these seven hours will pay in spades. Dragon Innovation has had many notable clients over the years – Pebble, Sphero, Makerbot, to name a few. They help startups find their way through the manufacturing mine-feild, for a fee of course. The founders are former iRobot employees, and have quite a bit of hard fought, yet free knowledge to share.

You’ll learn about how important decisions early on can make huge impacts on the success or failure of a product. There’s quite a bit of raw technical info on injection molding, design for manufacture, testing, pricing and everything under the sun. So do yourself (and everyone else) a favor, and before you click submit on that Kickstarter campaign, sit back and enjoy this free seminar.

We’re really enjoying the manufacturing oriented videos which have been popping up. Just a couple of weeks ago we came across a pair of hardware talks from [Bunnie Huang] that were a pleasure to watch. At 20 minutes this might be a good primer before you take the plunge with the playlist below.

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Mostly Non-Volatile Memory With Supercapacitors

Back in the days of old, computers used EPROMs to store their most vital data – usually character maps and a BASIC interpreter. The nature of these EPROMs meant you could write to them easily enough, but erasing them meant putting them under an ultraviolet light. Times have changed and now we have EEPROMs, which can be erased electronically, and Flash, the latest and greatest technology that would by any other name be called an EEPROM. [Nicholas] wanted an alternative to these 27xx-series EPROMs, and found his answer in supercapacitors.

[Nick]’s creation is a mostly non-volatile memory built around an old 62256 32k SRAM. SRAM is completely unlike EPROMs or Flash, in that it requires power to keep all its bits in memory. Capacitor technology has improved dramatically since the 1980s, and by using a supercap and one of these RAM chips, [Nick] has created a substitute for a 27-series EPROM that keeps all its memory alive for days at a time.

The circuit requires a small bit of electronics tucked between the EPROM socket and the SRAM chip; just enough to turn the 12 Volts coming from the EPROM programming pin to the 5 Volts expected from the SRAM’s Write Enable pin. This is accomplished by a few LEDs in series, and a 0.1F 5.5V supercap which keeps the SRAM alive when the power is off.

As for why anyone would want to do this when modern technologies like Flash can be found, we can think of two reasons. For strange EPROM sizes, old SRAMs abound, but a suitable Flash chip in the right package (and the right voltage) might be very hard to find. Also, EEPROMs have a write lifetime; SRAMs can be written to an infinite number of times. It’s not the best solution in every case, but it is certainly interesting, and could be useful for more than a few vintage computing enthusiasts.

This project makes us think of another where an LED may have been supplying keep-alive power to some volatile memory.

Rod Logic and Graphene: Elusive Molecule-Scale Computers

I collect slide rules. You probably know a slide rule is a mechanical calculator of sorts. They usually look like a ruler (hence the name) and have a sliding part (hence the name) and by using logarithms you can multiply and divide easily by doing number line addition and subtraction (among other things).

It is easy to dismiss old technology like that out of hand as being antiquated, but mechanical computing may be making a comeback. It may seem ancient, but mechanical adding machines, cash registers, and even weapon control computers were all mechanical devices a few decades ago and there were some pretty sophisticated techniques developed to make them work. Perhaps the most sophisticated of all was Babbage’s difference engine, even though he didn’t have the technology to make one that actually functioned (the Computer History Museum did though; you should see it operating in person, but this is good too).

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Breaking: Drone Registration Will Be Required Says US DoT

Today, the US Department of Transportation announced that unmanned aerial systems (UAS) will require registration in the future.

The announcement is not that UAS, quadcopters, or drones would be required to be registered immediately. This announcement is merely that a task force of representatives from the UAS industry, drone manufacturers, and manned aviation industries would provide recommendations to the Department of Transportation for what types of aircraft would require registration. The task force is expected to develop these recommendations and deliver a report by November 20.

A Short History of FAA Model Aircraft Regulation

Introduced in 1981, AC 91-57 was the model aircraft operating standards for more than 30 years. This standard suggested that model pilots not fly higher than 400 feet, and to notify a flight service station or control tower when flying within three miles of an airport.

The FAA Modernization And Reform Act Of 2012 (PDF) required the FAA to create a set of rules for unmanned aerial systems, however the FAA is expressly forbidden from, ‘promulgating any rule or regulation regarding model aircraft.’ The key term being, ‘model aircraft’. This term was defined by the FAA as being, “an unmanned aircraft that is capable of sustained flight in the atmosphere; flown within visual line of sight of the person operating the aircraft; and flown for hobby or recreational purposes.” Anything outside of this definition was an unmanned aerial system, and subject to FAA regulations.

While this definition of model aircraft would have been fine for the 1980s, technology has advanced since then. FPV flying, or putting a camera and video transmitter on a quadcopter, is an extraordinarily popular hobby now, and because it is not ‘line of sight’, it is outside the definition of ‘model aircraft’.

This interpretation has not seen a great deal of countenance from the model aircraft community; FPV flying is seen as a legitimate hobby and even a sport. The entire domain of model aircraft aviation is expanding, and the hobby has never been as popular as it is now.

The Safety of Model Aviation

The issue of drone regulation focuses nearly entirely on the safety of airways in the United States; model aviators flying within five miles of an airport must ask the airport or control tower for permission to fly. To that end, the FAA created the B4UFLY app that takes the trouble out of reading sectional charts and checking up on the latest NOTAMs and TFRs.

However, the FAA is increasingly concerned with drones, multicopters, and model aircraft. In a report issued last summer, the FAA cited a marked increase in the number of ‘close calls’ between manned aircraft and model aircraft. The Academy of Model Aeronautics went over this data and found a different story: only 3.5% of sightings were ‘close calls’ or ‘near misses’. The FAA data is questionable – the reports cited include a drone flying at 51,000 feet over Washington DC. Not only is this higher than any civilian passenger aircraft capable of flying, the ability for any civilian remote-controlled aircraft to operate at this altitude is questionable at best.

Nevertheless, the requirement for registration has been greatly influenced by the perceived concerns of regulators for mid-air collisions.

What exactly will require registration?

The group of industry representatives responsible for delivering the recommendations to the Department of Transportation will take into account what aircraft should be exempt from registration due to a low safety risk. Most likely, small toy quadcopters will be exempt from registration; it’s difficult to fly a small Cheerson quadcopter outside anyway. Whether this will affect larger quadcopters and drones such as the DJI Phantom, or 250 class FPV racing quadcopters remains to be seen.

Repairing $55,000 of Vintage Core Memory

If you find yourself in the vicinity of Mountain View, California you really should stop by the Computer History Museum. Even if you aren’t into the retrocomputer scene, there’s so much cool hardware ranging from a replica of the Babbage engine to nearly modern PCs. There’s even a room dedicated to classic video games. There are two fully working old computers at the museum that have their own special rooms: a PDP-1 (complete with vector scope to run Space War) and an IBM 1401.

The IBM 1401 looks like big iron, but in its day it was a low-end machine (costing an innovative business about $2500 a month). The base unit had 4000 words of magnetic core memory, but if you had a hankering for more memory, you could add the 350 pound dishwasher-sized IBM 1406 (for only $1575 a month or you could buy for $55100). How much memory did you get for $18900 a year? An extra 12000 words!

The problem is, the museum’s 1406 had developed a problem. Some addresses ending in 2, 4 or 6 failed and they were all in the same 4K block. [Ken Shirriff] was asked to go in and try to find the problem. We don’t want to give away the story, but [Ken] wrote up his experience (with lots of pictures).

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