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Puzzles articles
Puzzles
Consider the Boolean function F = ( x1 + x3 + x4 )(x2 + x3 + x4 )(x1 + x2 +x4)(x1 +x3 +x4)( x1 +x2 + x3 ). Find an assignment of x1; x2; x3 and x4 that will make F=1. You are not allowed to transform the expression into any other form including SOP, K-Map etc. (a) Explain the strategy that you used clearly. (b) Write down the assignment to X. Write function F in Problem above in sum-of-products form. Find an assign-ment of x1; x2; x3 a…
Puzzles
"In The Feynman Lectures on Computation , Richard Feynman poses an interesting little puzzle involving the synchronization of finite state machines acting as generals and soldiers. While he was able to find an answer to the problem, the minimum time solution apparently eluded him, and he ended his description of the puzzle with the following Fermat-like declaration : 'Somebody has actually found a solution with this minimum time. That …
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Murugavel Ganesan
September 16, 2008
Puzzles
Hello All: In fact it has been a long time since we had posted any sort of interview questions or puzzles and so here we are with a very practical problem. Lets see how many of you can crack it! I will post the solutions depending on the responses. Thanks. The problem: The Sheel lock Company has recently received an order from Mr. Manmohan Singh for their all-digital Perfectly Perplexing Padlock(P3). The P3 has two buttons ("0"…
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Murugavel Ganesan
September 15, 2008
Verilog
VLSI design interviews mix three kinds of questions: aptitude and analytical puzzles, quick logic design brain-teasers, and deeper questions on RTL, verification, test and physical design. This page collects them in one place: the original puzzle index with links to every question tagged "Interview Questions" on this blog, a digest of eleven classic ASIC puzzles, and eight puzzles solved here step by step, with Verilog where it helps. …
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The Editor's Desk
October 23, 2007
Puzzles
If performance doubles every two years, by what percentage does performance go up every month? :-)
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The Editor's Desk
September 07, 2007
Puzzles
No. A 2:1 multiplexer cannot be built from XOR gates alone, even if you are allowed the constants 0 and 1. Every circuit made only of XOR gates computes a linear (affine) function of its inputs, an XOR of some inputs and possibly a constant 1, and a mux needs a product term (the select signal ANDed with data), which no XOR network can produce. Add a single AND gate, however, and the mux becomes easy: y = a XOR (s AND (a XOR b)). Key takeaways…
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The Editor's Desk
November 25, 2005
