Subject:
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Re: Rotating through a four-bit nibble
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Newsgroups:
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lugnet.robotics
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Date:
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Thu, 22 Sep 2005 21:29:20 GMT
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Viewed:
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1600 times
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In lugnet.robotics, Jordan Bradford wrote:
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In lugnet.robotics, Geoffrey Hyde wrote:
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“Jordan Bradford” bradfj23REMOVE_THIS_SPAM_THINGY@uwosh.edu wrote in
message news:In7A20.1sK1@lugnet.com...
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In lugnet.robotics, Kevin L. Clague wrote:
Why in the world wouldn’t the firmware support shifting? The hardware
certainly does.
Heh, using multiply and divide to simulate shifting is kind of backwards.
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The problem is, multiplication and division to a binary CPU, as is the case
here, is just a whole series of instructions.
Here is the basic principle explained, partway down the page:
http://www.evergreen.edu/biophysics/technotes/misc/binmath.htm
A link to binary addition and subtraction, from HowStuffWorks article on
binary (it’s actually a framed link to a different site, may have to cut out
the frame addition if it doesn’t work properly), note how it essentially
works the same as decimal multiplication/division - also partway down the
page.
http://computer.howstuffworks.com/framed.htm?parent=bytes.htm&url=http://www.math.grin.edu/~rebelsky/Courses/152/97F/Readings/student-binary.html
Hope this helps you understand it better! :)
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Kev
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Understand what better? Binary math? No problems with that!
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Nice to hear from another bit twiddler....
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By “backwards” I meant that multiplication and division by powers of 2 are
usually changed to shift L/R by compilers. Also, I am amused that because the
firmware doesn’t use the H8/300’s shift instructions for whatever reason,
people are now trying to write software simulations of a trivial hardware
operation.
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I do find it ironic that the firmware suports bitwise AND and OR, but not XOR,
and also not shifts. Gack!
Well, at least we’re not having to use loops to add things to themselves to
simulate multiplying by a power of two!
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Message has 1 Reply:
 | | Re: Rotating through a four-bit nibble
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| (...) With that limitation we'd be creating a register (or Turing) machine simulator, too. It would be interesting to see a real-world processor that only has increment and decrement instructions. I'm thinking the LEGO firmware doesn't support these (...) (19 years ago, 29-Sep-05, to lugnet.robotics, FTX)
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Message is in Reply To:
| | Re: Rotating through a four-bit nibble
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| (...) Understand what better? Binary math? No problems with that! By "backwards" I meant that multiplication and division by powers of 2 are usually changed to shift L/R by compilers. Also, I am amused that because the firmware doesn't use the (...) (19 years ago, 22-Sep-05, to lugnet.robotics, FTX)
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