[Coco] Simple Coco bus buffer for HW folks

[Leslie Ayling]

Hi Matt,

Looks good.
I'd be interested to see the board layout files.

Not sure it's wise driving the *NMI , *HALT and *SLENB inputs
direct from the Cyclone2 though?
They're all pulled up to +5v internally via 4.7k resistors.

(*CART as well, but through a 10k resistor)

Cheers,
Leslie




Original Message:
Date: Sun, 19 May 2013 19:25:12 -0400
From: Matthew D Stock <stock at csgeeks.org>
Subject: [Coco] Simple Coco bus buffer for HW folks
To: 'CoCoList for Color Computer Enthusiasts' <coco at maltedmedia.com>
Message-ID: <51995F58.8030507 at csgeeks.org>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

[ I tried sending this before, but I think from the wrong account. Sorry 
if this is a dup. ]

I put together a little board to help me with my hardware development, 
and I thought that it might help others as well.  It's essentially a 
stripped down version of my ROM/device emulator - just the buffer chips 
and a pin header breaking out all of the needed stuff.  The header is 
compatible with the GPIO header for the Terasic DE1 FPGA dev board, but 
obviously it can be used with anything, both 3.3v and 5v, provided that 
it can supply the board with 3.3v.

Take a look at the video to see a quick demo using the FPGA as a ROM: 
http://www.youtube.com/watch?v=ttf82tPXUko. Overkill, but you get the idea.

When I have a few minutes I'm going to put the board layout and 
schematic up on the web.  I also intend to sell populated board for 
those of you who don't like to do fine pitch SMD soldering.  Haven't 
finalized a price yet, but I believe it will be around $35.  If you're 
interested, send me a note.

I'm still working on the ROM board, but I'm playing around with some 
options to make it cheaper and more flexible.
   -Matt