Q-bus I/O project

David Bridgham dab at froghouse.org
Sat Oct 10 13:10:25 CDT 2015

Wow.  A pretty board indeed.  Thanks for showing it off.  This is also
interesting to me since  a friend and I have been talking about building
something rather similar (and entirely different at the same time, we're
just focusing on the mass storage function and using an FPGA).  I'm
curious about some things though, if you'd be willing.

Bus drivers (along with voltage level conversion) have been a problem. 
You seem to be using 74LVC parts.  Are they close enough?  Though I also
see a bunch of FETs down there.

I've used OSHPark in the past for small boards but for 45 sq.in. boards
they'd seem to be awfully expensive, even if using their medium run
pricing.  The fingers look gold plated.  It could be just the ENIG
finish but I also see little tails running off the bottom as if you're
setup for hard gold plating.  Does OSHPark have that capability?

I gotta say that I'm impressed with your soldering skill as well as
stamina.  I was going to ask if it was machine assembled but I see in a
later message that it wasn't.  I was hoping for the Pick 'n' Paste
machine to come along and save me from having to do all that by hand but
that project seems to have faded away.

I'm curious why you didn't use resistor networks instead of discrete

I also love that your design tool put omegas on the silk screen for the
resistor values.


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