[Coco] new mylars

[Mark Marlette]

I did layout my first memory board by hand, just to say I did it.

Took me, IIRC a full day. This was a simple board as well.

It took the Specctra, yes, 8 seconds. The SuperIDE took the same computer over 200 seconds to route that card. Every trick in the book was used on that board as it should have been a four layer card.

Ground bounce is a bad thing. I have had the luxury of taking high speed layout classes at work, priceless! Matching differential signals on trace lengths very critical.

Been with Orcad since it it's first version release over 25 years ago.

I'll agree with your approach on the simpler boards, but when it comes to power planes, it is hard to keep them on just one side in a complex design. A trick is to have planes on both sides then tie together with vias....makes a small cap.

What is nice is that the tools are there, something even back in the late 90's where very expensive are now free or low cost.

At work they spend several seven digits a year with Mentor Graphics......I won't be moving to that platform any time soon..... :)

 
Mark Marlette 
http://www.cloud9tech.com 
mark at cloud9tech.com 


________________________________
From: Zippster <zippster278 at gmail.com>
To: CoCoList for Color Computer Enthusiasts <coco at maltedmedia.com> 
Sent: Tuesday, August 11, 2015 12:55 PM
Subject: Re: [Coco] new mylars


It’s true that what I’m saying probably only applies to Eagle and maybe some other free or cheap tools.

All of my PCB CAD experience has been in Eagle, except for a tiny amount of Kicad.

I think that even if you have access to better tools though, it’s probably good to learn how to manually route things,
to learn why to route things a certain way (routing features you mentioned and more).

- Ed





> On Aug 11, 2015, at 12:43 PM, Mark Marlette <mmarlette at frontiernet.net> wrote:
> 
> I'll add to this nearly irrelevant side-track as Ed put it... :)
> I have no experience in Eagle as I spend all my time in Specctra and Orcad by Cadence. These are far from free or cheap tools, but they work and work well.
> I place all components by hand then autoroute, review, adjust if needed and reroute. You can override the tool if needed but rarely is required. Specctra files are ASCII, so it is nice to go into the file and adjust, if you know the language, which I do.
> Analog and digital fences, Manhattan length control, just to name a few ....
> Just like in my shop.....power tools! :)
> YMMV.
> Regards,
>  Mark Marlette
> http://www.cloud9tech.com
> mark at cloud9tech.com
> 
>      From: Zippster <zippster278 at gmail.com>
> To: CoCoList for Color Computer Enthusiasts <coco at maltedmedia.com> 
> Sent: Tuesday, August 11, 2015 10:44 AM
> Subject: Re: [Coco] new mylars
> 
> A side note to laying out circuits with Eagle or similar and using the autorouter.
> If there was one piece of advice I’d give on autorouters, it would be to pretend they
> don’t exist.
> 
> It does take a long time to lay things out manually, but it’s well worth it.
> Even a well-designed circuit with good component placement on the board gets
> very meh when the autorouter is applied to it.
> 
> Are autorouted boards functional?  Yes, usually.  They are also terribly inefficient in terms of
> vias and proper power distribution (proper ground plane especially).  Also, they destroy layout
> aesthetics, which might not matter to some, but I think is important.
> 
> Anyway, nearly irrelevant side-track over…  :)
> 
> - Ed


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