Harvard Researchers Build 10 Robot

Theres been a lot of attention in the last year about various initiatives to encourage children to learn how to code; with new programming languages and of course the inexpensive and increasingly popular Raspberry Pi computer. To this we can now add a robot developed by Harvard University researchers that will cost just $10. The "Affordable Education Robot is a low-cost robot designed to introduce students of all ages to the fundamentals of programming and control of robots, with the hope of inspiring them to further pursue studies in Science, Technology, Engineering and Math (STEM)." Learn more about this robot here.



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Dr Gene Amdahl November 16 1922 – November 10 2015

Computer Pioneer, Mainframe Computer Architect & Entrepreneur

He is remembered for Amdahls law that basically states that the intrinsically serial part of any algorithm will limit the benefits from parallel processing. He was one of the architects of the IBM System/360 line of computers that dominated the mainframe industry and are still a force today. He was a champion of high-end uniprocessing.
Read his biography in the New York Times.
   I am grateful to Dr Amdahl for creating a company at which I was able to work as a computer architect for 6 years, 1976-82 and consult at for more. I did not have much to do with him directly – he was way above my level and he left to form a new company in 1979. But some anecdotes are in order.
   Dr Amdahl was revered by his Engineering Staff. He had a great knack of inventing rules of thumb to guide the designers. One was "one megabyte of I/O for every MIP of performance". Another, I remember vaguely, was that "caches should be square" (as many lines as bits in a line.) These were not necessarily correct rules but it was better to make the decision and get down to design rather than dithering (even better, of course, to measure and model.) He also had sound advice on functional architecture for speed – when you see an instructions operation code, you should immediately know the operand address and where the next instruction is located.
   I noticed that Dr Amdahl was allowed to have opinions but he insisted that those with contrary opinions had to have facts. As the technology and markets changed, many of his assumptions had to be challenged. I was with the group that developed the high level characteristics of the 580. I remember us having to justify 2-way multiprocessing as being required because our main market was for capacity rather than solely for speed and one could no longer design uniprocessors that could compete. I remember once having to tell him that his favorite division algorithm as used in the 470V (involving finding the reciprocal using Newtons formula and multiplication) was actually slower than the expected speed of straightforward non-restoring division. When our arguments were solid he just accepted them and moved-on.  He had to also accept microprogramming and memory chips for registers but I recall he embraced this and came up himself with a clever microcode scheme with two microstores, accessed simultaneously and each microinstruction including an address for the other memory – so each microinstruction could branch with no penalty.
   My closest encounter with Dr Amdahl was when he was trying to get the 580 design started. The 470V used 100-gate ECL chips with 80 I/O pins. Fujitsu was developing the next technology with 400 gates per chip but still with 80 I/O. The Amdahl Corp. engineers were adamant that they couldnt design a faster computer and reduce the chip count because the I/O count was not adequate (this was because even with 100 gates they could not use them all in some cases and the famous "Rents Rule" requiring I/O to rise with chip density.)  Dr Amdahl was dis-satisfied and hatched a plan to jolt the engineers into creativity by engaging with the Architecture group over the design.
   So, Inder Singh (later to found the Ethernet switching company Excelan) and I found ourselves closeted with Dr Amdahl in his office. He presented us with copies of his handwritten logic for the 580 execution unit (a piece is below and I have put the whole thing on the web as it must be the last time when a major computers logic was specified in handwriting.) Our meeting was on a Friday and he left us with the task of coming up with a design by the following Monday!

   My wife and I were going to Carmel for that weekend but I decided that would make no difference to my chances of arriving at a design by Monday so we went anyway. The Monday meeting was delayed until Thursday (phew!) and by then Inder and I had come up with some evidence that the execution unit could be "bit sliced" with multiple levels of logic within the chip (this was not at all original as there were microprocessors taking the same approach.) Basically we said "yes sir, you are right, it can be done. He then took a team of engineers with him on a sales trip to Scandinavia where they had to stay in the hotels and work on the new design – as a result the 580 was code-named Oslo. I think that part of the problem was that Engineers preferred circuit diagrams to logic equations but Dr Amdahl was a logic whizz.
It is hard to gauge the impact of Dr Amdahl and his engineering team on the process of designing fast computers but, if it could be known, I am sure that it would be profound. The Amdahl approach of making the processor pipeline central to the design, demonstrating that pipeline interlocks could be controlled without loss of performance (itself derived form earlier IBM projects), and that fast computers could be microprogrammed,  gradually became known throughout the "valley" as design engineers moved on to new jobs.

Amdahl, the man and his company, were quite a phenomenon!

[Post written by Bob Doran]

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10 awesome internet hacks to make your life better

Well Im not  sure that they are "awesome" but they are potentially useful, interesting or just fun. The Guardian recently published "10 awesome internet hacks to make your life better" that range from: how to log out of Facebook remotely if you left it running on a friends or relatives computer, how to bring up an emoji keyboard on your Mac or PC, and how to watch YouTube in slow motion. 

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Basic PLC Ladder Programming Examples 10

Basic PLC Ladder Programming Training Examples for Beginners.

 Hi friends here we are starting here a series of Free Training on PLC Ladder Programming training & tutorials.These PLC Ladder Programs are important to get basics of Ladder programs.

 PLC Ladder Practice Problem: 

Automatically infusing the container with liquids A and B in order when START is pressed.When it reaches the set level, mix the two liquids evenly then open the valve to let out the mixture.

Topics Covered in this example is PLC based Batch Process.

Number of PLC Inputs Required

X1 – Start Switch.

X1 – Low level float sensor. X1 = ON when the liquid level reaches X1.

X2 – High level float sensor. X2 = ON when the liquid level reaches X2.

X3 – Stop Switch.

X10 - EMERGENCY STOP button. X10 = ON when the button is pressed.

Number of PLC Outputs Required

Y0 – Liquid A Inlet

Y1 – Liquid B Inlet

Y2 – Mixture Outlet

Y3 – Agitator /Stirrer

Number of PLC Timer Required

T0 – 60 second Timer, 100 ms Time Base. (See K60 Preset Value for Timer)

T1 – 120 second Timer, 100 ms Time Base. (See K1200 Preset Val. for Timer)

PLC Ladder Programming:

 

PLC Ladder Program Description:

·        X0 = ON when START is pressed. Y0 will be ON and latched, and the valve will be opened for infusing liquid A until the level reaches the low-level float sensor. 

·        X1 = ON when the level reaches the low-level float sensor. Y1 will be ON and latched, and the valve will be opened for infusing liquid B until the level reaches the high-level float sensor.  

·        X2 = ON when the level reaches the high-level float sensor. Y3 will be ON and activates the agitator. Also, timer T0 will start to count for 60 sec. After 60 sec, T0 will be ON, and the agitator motor Y3 will stop working. Y2 will be ON and latched, and the mixture will drain out of the container. 

·        When Y2 = ON, timer T1 will start to count for 120 sec. After 120 sec, T1 will be ON and Y2 will be OFF. The draining process will be stopped. 

·        When an error occurs, press EMERGENCY STOP button X10. The NC contact X10 will be ON to disable all the outputs. The system will then stop running.

Note: Example is only for training purposes. No practical implementation is done. 

 See More PLC Ladder Programming Examples

PLC Ladder Programming Example 1

PLC Ladder Programming Example 2

PLC Ladder Programming Example 3

PLC Ladder Programming Example 4

PLC Ladder Programming Example 5

PLC Ladder Programming Example 6

PLC Ladder Programming Example 7

PLC Ladder Programming Example 8

PLC Ladder Programming Example 9

PLC Ladder Programming Example 10

PLC Ladder Programming Example 11

PLC Ladder Programming Example 12

PLC Ladder Programming Example 13

PLC Ladder Programming Example 14

PLC Ladder Programming Example 15

 

 

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