Metric or Imperial does not make any real difference (except individual preference) 
except when having to convert.

I think the point is that Protel has never handled Metric properly due to, what I 
assume is shoddy conversion due to database limitations. Metric support in the SCH for 
rules definition was skipped altogether until DXP (NOT).

Not all imperial values do work out to round numbers due to the generous tolerances 
that manufacturers apply to their values in data sheets. Try measuring a 20 mil 
(0.5mm) device and see! 

What is missed in the argument is that we will have rounding errors either way unless 
the s/w and/or database supports BOTH systems equally or not at all, and that includes 
the rules system.

At the moment P99SE supports metric units very badly (and not at all in SCH PCB 
rules), and DXP is not that much better.

So while both sides of the world battle the morals of Metric vs Imperial (irrelevant 
anyway), Protel (Altium) seem to have adopted the attitude of Imperial support for DXP 
SCH->PCBrules only (& just throw Metric users a scrap or 2 to keep them happy).

Nice way to get people to pay their ATS costs.....   :)

Best Regards

John A. Ross

RSD Communications Ltd
8 BorrowMeadow Road
Springkerse Industrial Estate
Stirling, Scotland FK7 7UW

Tel     +44 [0]1786 450572 Ext 225 (Office)
Tel     +44 [0]1786 450572 Ext 248 (Lab)
Fax     +44 [0]1786 474653
GSM     +44 [0]7831 373727

Email   [EMAIL PROTECTED]
WWW     http://www.rsd.tv
========================================== 










> -----Original Message-----
> From: vincent mail [mailto:[EMAIL PROTECTED]]
> Sent: 01 August 2002 15:04
> To: Protel EDA Forum
> Subject: Re: [PEDA] DXP comment, but slightly off topic
> 
> ok . open any electronics component catalog.  ( digikey , 
> mouser , avnet 
> , farnell ,newark arrow )and look at parts
> 
> you fill find things like 50 mils 25 mils 100 mils for lead pitch and 
> widths. and then look at the equivalent in millimeters. Which numbers 
> would you rather key in to create a new footprint ? Sure there are 
> metric parts but we don't use them ( yet ) . Ribbon cable is 
> still a 100 
> mil pitch , Smd components ares still 50 mil pitch ( some 
> tqfp and bga's 
> are in millimeters true )  and i'd rather key in 25 mils when 
> creating a 
> part then a crazy value like 0.62954 millimeter.
> 
> i think we will only be successful in switching to millimeter 
> when there 
> are no more parts made using imperial pitches. and that is 
> not going to 
> happen for a long time.
> 
> And believe me i know what a pain converting is , I am from 
> belgium and 
> have grown up with the metric system , after 2 years in the usa using 
> inches , and feet and pound and gallon that heve no linear 
> relationship 
> to them is still a nightmare. But for board layout i 
> translates in nice 
> round numbers.
> 
> > In a global economy standardisation is essential, do you 
> really think 
> > that inches have a future?
> > The IPC recognises this, which being American based is very 
> > surprising, but encouraging.
> > Even Britain the bastion of Imperial is slowly but 
> inexorably moving 
> > towards metrication.
> > I was brought up on imperial and pounds and shillings, so 
> I'm fairly 
> > understanding.
> > As far as I'm aware the USA is the only country that doesn't have a 
> > metrication programme in effect
> 
> 
> >
> > Chris Mogford.
> > 
> **************************************************************
> **********
> > * Tracking #: E7E9D6B0EAA28E45B0C48EF8E6F4E50D563153A1
> > *
> > 
> **************************************************************
> **********
> >
> 
> 
> -- 
> -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
>      _____________
> 


Vincent,

I think the point is that regardless of the units system, that Protel should support 
BOTH properly.







Best Regards

John A. Ross

RSD Communications Ltd
8 BorrowMeadow Road
Springkerse Industrial Estate
Stirling, Scotland FK7 7UW

Tel     +44 [0]1786 450572 Ext 225 (Office)
Tel     +44 [0]1786 450572 Ext 248 (Lab)
Fax     +44 [0]1786 474653
GSM     +44 [0]7831 373727

Email   [EMAIL PROTECTED]
WWW     http://www.rsd.tv
==========================================

    /____________/  Vincent Himpe
>    // _____  ___/   Lab Manager
>   / \ \   / /  /    ST Microelectronics
>  /___\ \ / /  /     5510 Six Forks Road . Suite 200
> /______//_/__/      Raleigh NC 27612
> 
>                     Tel : (919) 850 6070
>                     Fax : (919) 850 6689
>                     e-mail : [EMAIL PROTECTED]
> 
> -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
> 
> 
> 
> 
> 
> 

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