where does the word "barrel" come from in the name or what does it mean?
As in the barrel of a gun. When it rotates, it takes all of the bits a particular distance at once.
This is in contrast to earlier register-based single shifting mechanisms based on chains of flip flops.
The calculation is incorrect: It should be simply log2 n. This assumes (for simplicity) that each of the multiplexers are n bits wide. The first stage shift's across 1 bit line, the next 2 lines, 4, 8, and so on. An interesting side-effect of this arrangement is that the shift number is specified directly in binary notation, without the need for a decoder of any sort. — Preceding unsigned comment added by REH2 (talk • contribs) 14:52, 23 February 2011 (UTC)
like at http://www-comm.cs.shinshu-u.ac.jp/public/comparch/node45.html or http://www.realworldtech.com/page.cfm?ArticleID=RWT081502231107&p=3 `a5b (talk) 21:17, 5 July 2011 (UTC)
- here www.lirmm.fr/arith18/papers/hilewitz-PerformingBitManipulations.pdf at page 9 are pictured two types of barell shifters: classic one and log shifter. `a5b (talk) 21:35, 5 July 2011 (UTC)
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Is there any consensus on the inventor of the barrel-style shifter, or on the first processor to implement it? I recall that Seymour Cray used one in the CDC 6600 ca. 1963-4. Some casual Internet searching suggests that Burroughs may also have a claim, possibly with its B5000. (Note that I'm not talking about the CDC 6600's I/O system, which has been described using the similar-but-unrelated term “barrel and slot”.) 188.8.131.52 (talk) 01:54, 13 April 2014 (UTC)