classic hacks-hackers

While Boston Dynamics’ Big Dog is pretty impressive

of the US Army’s first attempt at a quadruped vehicle. Created in the early 1960s with the help of GE, this Army experiment was the first successful attempt of replicating a four-legged animal with a mechanical machine.

This “Walking Truck” was driven by a single operator who moved each of the vehicle’s legs using force-feedback hydraulic levers. Choreographing the machine’s movement was quite complicated, and during testing the Army found that the operator needed a mental break after only 15 minutes of use. As you can see in the video, the vehicle flexes some serious muscle. It kicks a Jeep out of its way with little effort, but it is still able to gently step on a light bulb without breaking it, due to the level of tactile feedback received by the operator.

If it weren’t for government budget cuts, we could be living out [George Lucas’] dream of AT-AT based combat right this minute!
How many 555 timers does it take to add up two 10 digit numbers? [Alan'sdoes it with 102 of them, he designed the machine as an extreme

entry to the 555 contest and the original plan was to make it even more complicated. This machine uses the 555′s to implement a nine decade accumulator and multiplexer, all inputs are managed by an old school dial from a rotary phone which apparently provide nicely timed outputs. Addition and subtraction are achieved using 9s compliment arithmetic which he discusses in the video after the break, for anyone who wants to brush up on 9s compliment or 555 theory.

Alan’s website has some nice pictures (We’re particularly impressed by all that minimalistic soldering) including schematics, and a very nice 33 minute video in which he discusses in detail how the machine works and even offers some history on the Pascaline, which is mechanical calculator that works on similar principles.
If you are a frequent reader, you are undoubtedly familiar with hacker [Sprite_tm]. He has been working with fellow members of the TkkrLab hackerspace to get things ready for their official grand opening on May 28th, and wrote in to share

As part of their preparations, they have been stocking the joint with all sorts of hacker-friendly goodies including plenty of tools and Club Mate, as well as a vintage ‘1943’ arcade cabinet. The game is a group favorite, though every time the power is turned off, it loses all of the hard-earned high scores. [Sprite_tm] knew he could improve on the current paper-based score register, so he pulled the machine open to see what could be done.

He used an AVR to tap into the machine’s Z80 logic board, allowing him to read and write to the entirety of the game’s RAM whenever he pleased. This enabled him to keep tabs on the high scores, restoring them to memory whenever the machine is powered back on. The addition of the AVR also allowed him to add a TCP/IP interface, which is used to send high scores to Twitter whenever someone beats the previous record.

His modular bus tap can be used in all sorts of Z80-based hardware, so if you have some vintage equipment laying around, be sure to swing by his site for a more detailed look at the build process.

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