[Coco] Simple Coco bus buffer for HW folks

[Matthew Stock]

Hi Leslie,

So you think those pullups might be too strong for the FPGA?  I'll take a
closer look at the chip specs.  The board layout (well, the kicad package
for everything) is up at http://www.bexkat.com/coco/busadapt.zip.
  -Matt



On Mon, May 20, 2013 at 8:27 AM, Leslie Ayling <layling at bigpond.net.au>wrote:

> 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
>
>
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