Alan Turing's life and legacy : A Salute

Alan Mathison Turing was an English mathematician, logician, cryptanalyst, andcomputer scientist. He was highly influential in the development of computer science, giving a formalisation of the concepts of "algorithm" and "computation" with the Turing machine, which can be considered a model of a general purpose computer.Turing is widely considered to be the father of computer science and artificial intelligence.

During World War II, Turing worked for the Government Code and Cypher School (GCCS) at Bletchley Park, Britain's codebreaking centre. For a time he was head of Hut 8, the section responsible for German naval cryptanalysis. He devised a number of techniques for breaking German ciphers, including the method of the bombe, an electromechanical machine that could find settings for the Enigma machine
.

This bombsight mechanical computer was used on board Lancaster and other aircraft in the Second World War. It was used to aim the bombs, taking factors such as aircraft height and speed and weather conditions into account. Unlike electronic computers, which are programmed using software, mechanical computers carried out their computations according to the physical shape and design of the mechanism. The gears, linkages and cams literally embodied the equations that needed to be solved.

After the war he worked at the National Physical Laboratory, where he created one of the first designs for a stored-program computer, the ACE. In 1948 Turing joined Max Newman's Computing Laboratory at Manchester University, where he assisted in the development of the Manchester computers.

The Pilot ACE was one of the first computers built in the United Kingdom, at the National Physical Laboratory (NPL) in the early 1950s.

It was a preliminary version of the full ACE, which had been designed by Alan Turing. After Turing left NPL (in part because he was disillusioned by the lack of progress on building the ACE), James H. Wilkinson took over the project, Harry Huskey helped with the design. The Pilot ACE ran its first program on May 10, 1950 and was demonstrated to the press in December 1950.

Codebreaker is an exhibition developed by the Science Museum to celebrate the centenary of the birth of this pioneering British figure.

At the heart of the exhibition is the Pilot ACE computer, built to Turing’s ground-breaking design. It is the most significant surviving Turing artefact in existence.

Alongside this remarkable machine is a sequence of exhibits showcasing Turing’s breadth of talent. Together with interactive exhibits, personal recollections and a wealth of historic imagery, the exhibition offers an absorbing retrospective view of one of Britain’s greatest twentieth-century thinkers.

This exhibition was made possible with the generous support of Google.

Watch Video : http://www.youtube.com/watch?v=I3NkVMHh0_Q

Alan Turing I salute your centenary. Where would the world be without your work and as the father of Computer Science.

References:

1. History of Computing in the Twentieth Century" edited by Gian-Carlo Rota et al, Academic Press (1980).
2.  J.H.Wilkinson, "Rounding Errors in Algebraic Processes", reprinted by Dover (1994).
3. Sciencemuseum.org
4. Agar, Jon (2003). The government machine: a revolutionary history of the computer. Cambridge, Massachusetts: MIT Press

A Small Project for "Newbies" : Fun Stuff : Bi-stable Multivibrator

Introduction

This is the circuit of the Bi-stable Multivibrator. Either transistor can be on while the other is off, and the circuit will retain its state until it is changed by an external signal or power is turned off. Thus, this circuit represents the simplest possible binary memory. In this experiment, you will construct and demonstrate such a circuit.

Schematic Diagram

If, when power is first applied, Q1 turns on, its output will be a logic 0. This will be applied to Q2's input resistor, keeping Q2 turned off so that its output will be a logic 1. This logic 1 will be applied back to Q1's input resistor, keeping Q1 turned on and holding the entire circuit locked into this stable state.

On the other hand, if Q1 stays off at power-up, it will apply a logic 1 to Q2's input, thus turning Q2 on. The resulting logic 0 output from Q2 will in turn hold Q1 off. The circuit will then remain in this stable state indefinitely.

This circuit is a bistable multivibrator, or flip-flop. Push "set" input at right switch to bring the output high (5V). Push the "reset" input at lower right to bring the output low (ground). 

The transistors are cross-coupled in such a way that the circuit has two stable states. Initially, Q2 is on and Q1 is off. Since Q1 is off, no current is flowing through it, and its collector voltage is close to 5V. This allows current to flow through into the base of Q2, which keeps Q2 switched on. Q2 is in saturation mode, keeping the collector voltage close to ground; this prevents any current from flowing into the base of Q1 to switch it on. 

If you push the "set" input momentarily, this provides base current to Q1, switching it on, bringing its collector low, which stops the base current flowing to Q2. So the circuit switches to the opposite state. Pushing the "reset" input switches back.

Because this circuit has two possible logical states, it is known technically as a multivibrator. Because it has two possible stable states, it is a bistable multivibrator. It is also the most basic possible binary latch circuit. In the next few experiments we'll look at ways to expand this circuit and modify its behavior. But first, we'll examine the operation of this basic circuit.

Here is the Simulation of Astable Multivibrator which is derived from internet, But the similarly this circuit will swithover LEDs after pressing the push buttons simultaneously in Bi-stable Multivibrator.

This is for example only, do not consider resistance values, voltage supplies, etc., the first figure is correct for this project.

Parts List

To construct and test the bistable multivibrator circuit on your breadboard, you will need the following experimental parts:

• (6) 1K, ¼-watt resistors (brown-black-red). 
• _{(2) 330E}, ¼-watt resistors (brown-black-red). 
• (2) BC547 or 2N4124 NPN silicon transistors.
• _{(2) Mini Push Button Switches} 
• (2)LEDs Green, Red 
• 5V Power Supply Adapter.
• White wire or existing jumpers. 
• Black wire or existing jumpers. 

Arduino Leonardo AVR Development Board

Arduino Leonardo AVR Development Board is a microcontroller board based on the Atmel ATmega32u4. It offers 20 digital IOs (of which 7 can be used as PWM outputs and 12 as analog inputs), a 16MHz crystal oscillator, a micro USB connection, a power jack, an ICSP header, and a reset button. The Leonardo differs from all preceding boards in that the ATmega32u4 has built-in USB communication, eliminating the need for a secondary processor. This allows the Leonardo to appear to a connected computer as an HID, such as a mouse or keyboard, in addition to a virtual (CDC) serial / COM port. The Leonardo board contains everything needed to support the microcontroller. Simply connect it to a computer with a USB cable or power it with an AC-to-DC adapter or battery to get started.

Specifications

Microcontroller: ATmega32u4
Operating voltage: 5V
Input voltage (recommended): 7-12V
Input voltage (limits): 6-20V
Digital I/O pins: 20
PWM channels: 7
Analog input channels: 12
DC current per I/O pin: 40mA
DC current for 3.3V pin: 50mA
Flash memory: 32Kb (ATmega32u4)
of which 4Kb is used by bootloader
SRAM: 2.5Kb (ATmega32u4)
EEPROM: 1Kb (ATmega32u4)
Clock speed: 16MHz
------------------------------------****

Here is one Hack that will give you example of extension if the application of the Leonardo.

The newly released Arduino Leonardo has a few very interesting features, most notably the ability to act as a USB keyboard and mouse.. This feature isn’t exclusive to the Leonoardo, as Michael explains in a build he sent in – the lowly Arduino Uno can also serve as a USB HID keyboard with just a firmware update.

The Arduino Uno (and Mega) communicate to your computer through a separate ATmega8U2 microcontroller. Simply by uploading new firmware with the Arduino Device Firmware Upgrade, it’s easy to have your old Arduino board gain some of the features of newer boards such as the Teensy or Leonardo.

Michael goes through the steps required to make this upgrade work and ends his build by showing off an Arduinofied ‘cut, copy and paste’ button project as well as a few multimedia controls. You can check those builds out in the video after the break.

If emulating a USB keyboard isn’t your thing, it’s also possible to install LUFA firmware to emulate everything from joysticks to USB audio devices. Very cool, and very useful.

Courtesy:

Mouser.com

www.hackaday.com

Introduction to Raspberry Pi : "Take a Byte"

The Raspberry Pi is a credit card sized single-board computer developed in the UK by the Raspberry Pi Foundation with the intention of stimulating the teaching of basic computer science in schools.

The Raspberry Pi has a Broadcom BCM2835 system on a chip (SoC), which includes an ARM1176JZF-S 700 MHz processor,VideoCore IV GPU, and 256 megabytes of RAM. It does not include a built-in hard disk or solid-state drive, but uses an SD card for booting and long-term storage.

Available two versions Priced at US$ 25 and US$ 35.

The Foundation provides Debian and Arch Linux ARM distributions for download. Also planned are tools for supporting Python as the main programming language, with support for BBC BASIC, (As "Brandy Basic", the BBC BASIC clone), C, and Perl.

HARDWARE:

Initial sales are of the Model B, with plans to release the Model A sometime later. Model A has one USB port and no Ethernet controller, and will cost less than the Model B with two USB ports and a 10/100 Ethernet controller.

Though the Model A doesn't have an RJ45 Ethernet port, it can connect to a network by using a user-supplied USB Ethernet or Wi-Fi adapter. There is in reality no difference between a model A with an external Ethernet adapter and a model B with one built in, because the Ethernet port of the model B is actually a built-in USB Ethernet adapter. As is typical of modern computers, generic USB keyboards and mice are compatible with the Raspberry Pi.

The Raspberry Pi does not come with a real-time clock, so an OS must use a network time server, or ask the user for time information at boot time to get access to time and date for file time and date stamping. However, a real-time clock (such as the DS1307) with battery backup can be added via the I²C interface.

Operating Systems

This is a list of operating systems running, ported or in the process of being ported to Raspberry Pi

• Full OS:
  • Arch Linux ARM
  • Debian Squeeze
  • Gentoo Linux
  • Google Chrome OS
  • Raspberry Pi Fedora Remix
  • Raspbian
  • RISC OS
  • Slackware ARM (formally ARMedslack)
  • QtonPi a cross-platform application framework based Linux distribution based on the Qt framework
  • NetBSD

• Multi-purpose light distributions:
  • Squeezed Arm Puppy, a version of Puppy Linux (Puppi) for the ARMv6 (sap6) specifically for the Raspberry Pi.

• Single-purpose light distributions:
• IPFire
• OpenELEC
• Raspbmc
• XBMC

What’s a Raspberry Pi?

The Raspberry Pi is a credit-card sized computer that plugs into your TV and a keyboard. It’s a capable little PC which can be used for many of the things that your desktop PC does, like spreadsheets, word-processing and games. It also plays high-definition video. We want to see it being used by kids all over the world to learn programming.

What’s the difference between Model A and Model B?

Model A has 128Mb of RAM
 Model A has been redesigned to have 256Mb RAM, one USB port and no Ethernet (network connection). Model B has 256Mb RAM, 2 USB port and an Ethernet port.

What are the dimensions of the Raspberry Pi?

The Raspberry Pi measures 85.60mm x 53.98mm x 17mm, with a little overlap for the SD card and connectors which project over the edges. It weighs 45g.

What SoC are they using?

The SoC is a Broadcom BCM2835. This contains an ARM1176JZFS, with floating point, running at 700Mhz, and a Videocore 4 GPU. The GPU is capable of BluRay quality playback, using H.264 at 40MBits/s. It has a fast 3D core accessed using the supplied OpenGL ES2.0 and OpenVG libraries.

Why did they select the ARM11?

Cost and performance.

How powerful is it?

The GPU provides Open GL ES 2.0, hardware-accelerated OpenVG, and 1080p30 H.264 high-profile decode.

The GPU is capable of 1Gpixel/s, 1.5Gtexel/s or 24 GFLOPs of general purpose compute and features a bunch of texture filtering and DMA infrastructure.

That is, graphics capabilities are roughly equivalent to Xbox 1 level of performance. Overall real world performance is something like a 300MHz Pentium 2, only with much, much swankier graphics.

Will it overclock?

There’s a little overclocking headroom – most devices will run happily at 800MHz. There’s no BIOS per se, but we do support booting bare metal code, so something could be done.

Can we add extra memory?

No. The RAM is a POP package on top of the SoC, so it’s not removable or swappable.

Is sound over HDMI supported?

Yes.

Is there a GPU binary?

Yes. The GPU binary also contains the first stage bootloader.

Can we add a touchscreen?

We haven’t experimented with any touchscreens yet, but there’s no electronic reason why it shouldn’t work. There’s lots of discussion about this on the forums. The main issue people are encountering seems to be one of cost; touchscreens are very pricey!