[A83] Re: some none-programming questions
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[A83] Re: some none-programming questions
>> 1 how to calculate pi?
>
>There are several different methods. A search on Google for something
along
>the lines of, oh, say, "how to calculate pi", would have turned up
>everything you were asking about. Funny how that works, huh?
>
>The method that you will learn about in calculus is the Leibniz method.
>arctan(pi / 4) = 1, so you can calculate pi using a definite integral.
In the other emails, I saw this 'arctan' too. Where can I find it on my
calc?
>> 2 what's the use of an ISP?
>
>Well, you might need an Internet Service Provider if you want to get
online.
>Why do you need an ISP? Or rather, what makes them so special? Good
>question. You need access to the internet somehow. Now, no one is just
>going to give you access to the internet, because it costs them something.
>You must connect through someone else. So who does everyone connect
>through? The top people that everyone connects through is known as a tier
1
>provider. These people essentially are the internet. The internet is
>connected through a type of star topology. A tier 1 provider has their own
>fiber, and is connected to other tier 1 provider, in different locations.
>They are either connected through themselves, or to someone else.
>Eventually everyone must connect to someone else. I believe that a
location
>in a city must be connected to five other cities.
>
>When you connect with someone else, you are peering with them. As I
>understand it, you basically agree to exchange traffic. When the fiber was
>laid, enough was laid that most is not used. This is because the cost of
>actually digging the trenches is much higher than the cost of the fiber, so
>everyone made sure that enough was there. Fiber means fiber optics. Data
>is transmitted using light, not electricity. The fiber that is not used is
>not lit, thus it is dark, hence the term dark fiber. At the point when you
>actually have your own fiber in the ground, there is essentially no limit
to
>the bandwidth.
Cool...
>The limits are imposed by the switching equipment and the
>equipment to interface with the fiber. Even for something as small as an
>OC3 or OC12, the equipment to to control the fiber is extremely expensive.
>Because fiber has a much higher bandwidth capacity than wire, it is
>desirable to keep everything as light. That is where optical switching
>comes into play. I don't know if these are used yet, or in widespread use,
>but they will definitely be used in the future.
>
>There is a lot more to the internet than that, but hopefully that will give
>you a small idea of how it all works. Say you wanted to start an ISP.
>First, you'd need bandwidth for people. So you'd call up the local telco,
>say AT&T, and order a T1. There are two parts to this. First is the
actual
>equipment and the local loop. This would more than likely come from the
>telco, as they own the lines. You would then have a direct connection
>between you and them. Then you need the actual data provider. Just the
>connection means nothing, if it's not connected anywhere. You could either
>get the connection from the telco, or from another ISP. If you get it from
>the ISP, then the telco would have a line between you and them, and between
>them and the other ISP, thus forming a direct connection between you and
the
>other ISP. That ISP would give you your connection by connecting you with
>their upstream provider, say a T3 from UUNET.
>
>I don't know the specifics on how this sort of thing works, and it seems a
>bit strange, but remember what I said about bandwidth being essentially
>free, if you have it. Hence the ability to connect you directly somewhere
>else, and you getting charged for something different than what the actual
>connection looks like.
>
>Now you have your T1 line. This is when you call up all your friends and
>brag about having a T1 in your basement, and invite everyone over for a big
>LAN party. Don't forget the chips, pizza and mountain dew.
:)
>Right, now how
>do you become an ISP? The way it used to be done is similiar to how you'd
>think. That's right, you get a bunch of phone lines and a bunch of modems,
>hook them up and off you go. There is also equipment that can do this
>digitally, so that you don't actually need any physical modems. The
>equipment works like a modem, but it handles a lot of connections at once.
>You can also outsource the dialup connections, as many ISP's do. Someone
>else handles all the incoming connections, routes the traffic to you, and
>you send it out to the internet.
>
>This information is probably not completely correct, but it's my basic
>understand of how things work, after having worked in the industry for a
few
>years.
Cool!
That was really long, but I really understand it now! :-)
>> another question, non-z80:
>> how to rotate a 'thingy' in 174 steps? Like a clock, but just a little
>block
>> that goes round. I was thinking of a table like the realistic-jump table,
>> but for a circle.
>
>Learn about trig.
Ah, trigonometry, I guess. Okay, let's look in my maths book.
Thanks,
Ronald
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