# Mapping

#### Dextraneous

Food for thought. I'm emailing a link to that to my 6th form tutor colleagues for points of discussion

When I teach how to use a PCB program I still use imperial units because they are still very prevalent in the PCB world (I really do need to update everything to use both) so it's interesting to see that map.

#### empip

Proficiency in both metric and Imperial - not rocket science, is it ?

In aerospace we did work for the USA, so 'our' metric stuff needed converting to USA imperialistic crap - No sweat, proficient in hours.

But then 'we' were a private company - customer is always ... and all that, made you think !

-0-

#### sooey

Anyone remember the famous spaceshot that went t*ts up because some software designers were using metric system and some others imperial?

#### JBR

Some different maps, one of which shows the countries that don't use the Metric system that we discussed a while back.

http://www.earth-pics.com/gallery/1...dn-039-t-teach-you-in-school-part-2/9[/QUOTE]

So, apart from a couple of small third-world countries, we are talking about only the USA. Or are we?

What about Britain? Yes, it is government policy that we now use decimal units for weights, lengths and so on, yet what about road signage? We still have speed limits and distances in miles and yards (for which, personally, I am grateful as that's how I think!). Call me a dinosaur, but I still think in pounds and ounces. For example, when I ask for 'a quarter of sweets', they know exactly what I mean. I believe it equates to around 100g.

I wonder how many other countries are listed nominally as metric, yet in practice sit on the fence!

In the world of PCB design they changed to metric ages ago.

It used to be all based on a 0.1" or 100th measurement.

Now we have pin pitches for IC's of 1.27mm instead of 50thou etc.
So all that has changed in the main is the way the measurements are given on datasheets. Only new IC's are on a true metric pitch.

Many other components are on imperial dimensions & they cannot change.

But we still prefer to think of measurements such as 8 thou track & gap rather than 0.2032 mm - a single number is far easier to remember than down to 4 places.

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