[Magic-dev] Re: Need some clarification on techfile

[R. Timothy Edwards]

Dear Mark,

> One thing that did confuse me, is the syntax of scalegrid.

> scalegrid a b

> is supposed to "Set the ratio of magic internal units to lambda units"

> On first reading, I interpret this to be a internal units to b lambda
> units, while in fact it is the other way around.  Maybe I am wrong,
> but that is how some others I have posed the question also interpret
> this.

Any change I make to this now could break all of my startup scripts.
One thing I could do is allow an alternate syntax:

	scalegrid b:a

or maybe just allow the suffix "l" and "i" to represent lambda and
internal, like I did for units of movement (e.g., "snap int; box move
e 3l" (3-ell) or "snap lambda; box move e 3i").  That would mean that

	scalegrid 2i 1l
and
	scalegrid 1l 2i

would be equivalent and unambiguous.  It would also avoid the *other*
confusion that you failed to mention, namely that "scalegrid a b"
is not even interpreted as "a lambda units to b internal units", but
rather "scale current grid by a factor of b to a", such that you get
the following sequence:

	: scalegrid 1 2
	2 Magic internal units = 1 Lambda
	: scalegrid 1 2
	4 Magic internal units = 1 Lambda

So stating absolute units of "i" and "l" would avoid the problem of
relative scaling when you may or may not know what the current scale
is (which, by the way, you can find out with the "tech lambda"
command, although one might rationally ask why you shouldn't get
the same answer by simply typing "scalegrid").

I'll work on it.

					---Tim

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| Dr. R. Timothy Edwards (Tim)   | email: tim at opencircuitdesign.com    |
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