Generating The Mandelbrot Set With IBM Mainframes

March 26, 2015 by Brian Benchoff 34 Comments

[Ken Shirriff] is apparently very cool, and when he found out the Computer History Museum had a working IBM 1401 mainframe, he decided to write a program. Not just any program, mind you; one that would generate a Mandelbrot fractal on a line printer.

The IBM 1401 is an odd beast. Even though it’s a fully transistorized computer, these transistors are germanium. These transistors are stuffed onto tiny cards with resistors, caps, and diodes, than then stuck in a pull-out card cage that, in IBM parlance, is called a ‘gate’. The computer used decimal arithmetic, and things like ‘bytes’ wouldn’t be standard for 20 years after this computer was designed – 4,000 characters of memory are stored in a 6-bit binary coded decimal format.

To the modern eye, the 1401 appears to be a very odd machine, but thanks to the ROPE compiler, [Ken] was able to develop his code and run it before committing it to punched cards. An IBM 029 keypunch was used to send the code from a PC to cards with the help of some USB-controlled relays.

With the deck of cards properly sorted, the 1401 was powered up, the cards loaded, and the impressive ‘Load’ button pressed. After 12 minutes of a line printer hammering out characters one at a time, a Mandelbrot fractal appears from a line printer. Interestingly, the first image of the Mandelbrot set was printed off a line printer in 1978. The IBM 1401 was introduced nearly 20 years before that.

Koch Lamp Is 3D Printed With A Twist

June 1, 2014 by Marsh 11 Comments

Koch Lamp

[repkid] didn’t set out to build a lamp, but that’s what he ended up with, and what a lamp he built. If the above-pictured shapes look familiar, it’s because you can’t visit Thingiverse without tripping over one of several designs, all based on a fractal better known as the Koch snowflake. Typically, however, these models are intended as vases, but [repkid] saw an opportunity to bring a couple of them together as a housing for his lighting fixture.

Tinkering with an old IKEA dioder wasn’t enough of a challenge, so [repkid] fired up his 3D printer and churned out three smaller Koch vases to serve as “bulbs” for the lamp. Inside, he affixed each LED strip to a laser-cut acrylic housing with clear tape. The three bulbs attach around a wooden base, which also holds a larger, central Koch print at its center. The base also contains a PICAXE 14M2 controller to run the dioder while collecting input from an attached wireless receiver. The final component is a custom control box—comprised of both 3D-printed and laser-cut parts—to provide a 3-dial remote. A simple spin communicates the red, green, and blue values through another PICAXE controller to the transmitter. Swing by his site for a detailed build log and an assortment of progress pictures.

HDTV Antenna That Can Hang In A Window

June 15, 2012 by Mike Szczys 38 Comments

We can’t wait to give this one a try. We’ve got a DIY HDTV antenna hanging out in the attic which was made from some scrap wood and eight metal coat hangers. It works great but it’s pretty ugly and not everyone has an attic to hide it in (not to mention the signal drop caused by the roof shingles). This is a fractal antenna anchored to some clear plastic so you can just hang it in the window and start picking up the over-the-air channels without much effort.

The pattern was modeled in SketchUp then printed out on two pieces of paper. One piece had it printed on both sides, which makes it easy to glue on a sheet of aluminum foil, then follow the pattern on the opposite side to cut out the important parts. The other template was used as an aligment guide when gluing the foil to the clear plastic. A coaxial adapter was then attached using nuts and machine screws. If you build it, let us know how it comes out!

Fractal Viewer Can Zoom And Enhance Like On CSI

January 31, 2012 by Mike Szczys 15 Comments

This fractal viewer is a great way to get your feet wet with Field-Programmable Gate Arrays. The project will give you some experience working with video output, user input, and a whole bunch of math and memory management. [Hamster] built it using the Papilio Plus board which hosts a Spartan 6 FPGA. This continues his odyssey into the realm of hardware design; part of which we looked at back in December.

The arcade Megawing for the dev board gives him easy access to the controls needed to scroll and zoom on the fractal design. Calculations to generate the shape are being run at 240 MHz, with the VGA output running at 80 MHz. The device has enough horse power and SRAM to show an 800×600 pixel output with a 60 Hz refresh rate.

We really liked the logic diagram that [Hamster] drew up when planning how the calculations would be handled. It’s not overly complex, but it took us a while to conceptualize how everything fits together. It’s certainly an improvement from his last attempt as we couldn’t make heads or tails out of that flow chart.

If you’re just interested in the pretty shapes and colors there’s a demo embedded after the break.

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ChipKIT Uno32: First Impressions And Benchmarks

May 27, 2011 by Phil Burgess 49 Comments

Following Maker Faire, we’ve had a few days to poke around with Digilent’s 32-bit Arduino-compatible chipKIT boards and compiler. We have some initial performance figures to report, along with impressions of the hardware and software.

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