[Coco] HD floppy controller update: success!

[Joel Ewy]

Phill Harvey-Smith wrote:
> Joel Ewy wrote:
>> Hey Chuck,  this is good stuff you're working on.
>
> I'll second that :)
>
>> If you do decide to manufacture some boards, my temptation level would
>> go sky high.  Cost would be a factor for me.  PCB only option would be
>> cool.  But I may have to download Eagle and see if I can fab a
>> double-sided board.  I have a homebrew CNC drill that I've done far too
>> little with so far.  I wonder where I can get ahold of the 82077AA.
>
> Humm having looked at the board produced by Eagle's auto-router, I
> think it would be hardish to produce that using DIY methods, either by
> your CNC, or by the photo etch process (as I use), as there are many
> through holes that would be almost impossible to hand top solder
> (specifically the ones for the PLCC).
>
Without having looked into it ahead of time, I'm wondering if there's
such a thing as a wire-wrap PLCC socket that could be installed with a
spacer allowing for top-soldering...  Oh, but there are those inside
rows... Looking at a PLCC socket, I  think one could carefully remove
some plastic from the middle of the bottom of the socket in order to get
a soldering iron down in there to do the inside rows.  Wretched, I
know.  But I think doable for a one-off board. 

Hopefully the slightly longer leads wouldn't become little ratio
transmitter towers, but I suppose that would be a possibility.  I've
certainly seen long socket leads used in things like CPU accelerator
boards and memory boards for the Amiga 1000, and those running at 8MHz
-- though I see a 24MHz crystal in there.
> The board would need to be re-routed with this in mind. As a fairly
> experienced Eagle user I have come to the conclusion that the
> auto-router is not too good other than for the simplest of jobs and I
> mostly tend to hand route things, yes it can mean a fair amount of
> tedious work, it can also mean ripping things and starting again, but
> overall the finished result will be easier to work with.
>
> I do however tend to optimise mostly for DIY photo etching where you
> don't have plated through holes, though you can of course use
> component legs for this purpose, using turned pin IC sockets also
> helps greatly as they can be top soldered, with a little practice, and
> taking care on the  order that you assemble the board.
>
I'm not opposed to the idea of re-laying-out the board to, e.g. put all
the inside row connections on the bottom of the board and all the
outside connections on the top.  But, of course, by the time one's gone
to that much effort, buying a board somebody else has had professionally
made becomes more attractive.

JCE
> This of course does not matter so much if you are going to have the
> board made by a board house, as they generally can do plated holes and
> so this isn't so much of a concern.
>
> All IMHO of course.
>
> Cheers,
>
> Phill.
>