Imperial Riddle out of My Astral Plane - Page 1
Forum section: electronics / general

author: Mechatrommer
author_rank: Super Contributor
timestamp: March 14, 2014, 05:21:07 am
content: 1 mil or 1 thou is 1/1000 of an inch... i saw some imperial ruler they are using 8 divisions for each inch, but a 1000 will not get us to integer exponent with base 8, ie 8^N = 1000, N is not integer. how is that can be? why they didnt decide 1 thou is 1/512 (8^3) or 1/4096 (8^4) of an inch? just like in computing industry 1K byte is actually 1024 bytes. hmmm.

author: daqq
author_rank: Super Contributor
timestamp: March 14, 2014, 05:43:22 am
content: Rule of thumb: When dealing with the imperial system and you are used to the metric system, expect crazy.See:http://upload.wikimedia.org/wikipedia/commons/thumb/1/1e/English_mass_units_graph.svg/400px-English_mass_units_graph.svg.pnghttp://upload.wikimedia.org/wikipedia/commons/c/c8/English_length_units_graph.pngI'm guessing they came up with the mil unit when they needed something practical instead of a horrible system.

author: chinglish
author_rank: Contributor
timestamp: March 14, 2014, 08:57:13 am
content: QuoteNo, he is right. A capital 'K' refers to the binary kilo.1 kB = 1000 bytes1 KB = 1024 bytes (do not use)1 KiB = 1024 bytesThis is only true for kilobytes tho. There is no gB or mB, etc.. Quite annoying. E.g. 1 GB might mean 1024^3 and also 1000^3. Guess what they use when they want to sell a HDD.

author: SeanB
author_rank: Super Contributor
timestamp: March 14, 2014, 06:41:06 pm
content: I bought assorted "8G" flash drives. Some format to 7.8Gb and some are 8Gb when formatted under Linux. Funny that.......

author: ajb
author_rank: Super Contributor
timestamp: March 14, 2014, 06:58:49 pm
content: The conventional division of inches is into halves, then quarters, then eighths, etc. These are still commonly used in carpentry in particular. Anyone who needs more than 1/32" (especially machinists) typically switches to decimal divisions, though. Fractional inches still influence common material sizes, so for instance 0.063" (~1/16"), 0.125" (1/8"), 0.190" (~3/16"), 0.250" are common thicknesses for metal stock, and thinner materials are often specified bygauge. sheet lumber is still sold by fractions, although nominally 3/4" material is often actually 23/32", 1/2" is 15/32", etc depending on the composition and whether or not it has been sanded.Just one of those quirks of the imperial system. You get used to it when you grow up with it and use it on a daily basis.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: March 14, 2014, 09:50:27 pm
content: "K" is Kelvin (absolute temperature), "k" is kilo (1000).Also, "b" is bit, "B" is byte (= 8b traditionally, but this is context-dependent as byte width can vary by platform). The binary prefixes are always uppercase followed by a lowercase 'i', e.g., "Ki" is kibi (1024).So...what was the question?You can divide meters into 8ths just as well as inches or attoparsecs. 1/8" = 125 mil. Is there something mysterious about that?Inch measuring devices in the US (and I suppose in the few other places that still use them as customary units; Canada and possibly Britain come to mind) are traditionally divided in powers of 2 fractions. This makes geometry easy -- you can always calculate a fraction by halving the next higher one -- and any fraction can be approximated as a binary fraction, which should be oddly familiar to embedded programmers, but is still not terribly alien to common folk as well.Correct me if I am wrong, but fractions are still taught in school in metric countries, no? So there's no loss of understanding there.As for decimal inches, those have been in use for a very long time -- though adoption varies by trade. I want to say aerospace still uses them a disturbing amount; conversely, there isn't a machinist worth his salt that doesn't understand decimal inches (measured in "thous" rather than mils, but same thing).I personally use customary fractional inches for most mechanical drawings (although I've been in the habit more often of expressing the rounded decimal equivalents), metric (MKS, with multipliers as needed) for technical calculations, and inches/mils for PCB layouts (though any CAD drawings and footprints involved remain in their primary units).Anything else I punch into Google Calculator and let it handle the conversion.Tim