[Coco] Coco Cartridge Prototyping Pak PCB

[Chris]

Looks good!

On Wednesday, October 8, 2014, Zippster <zippster278 at gmail.com> wrote:

> Hi Kip,
>
> Looks good to me based on the renderings.
>
> Except I would clean up the silkscreen.  I volunteer to help with that if
> you like.
> What software was used to draw it up?
>
> I’m definitely thinking PCBCart is the way to go, as it won’t take many
> boards
> to come out far, far ahead of OSH Park dollar wise.  And the gold plating
> on the card
> edge won’t just be the enig finish that way either.
>
> Looks like a very good basis for any number of projects!
>
> - Ed
>
>
> On Oct 8, 2014, at 5:20 PM, Kip Koon <computerdoc at sc.rr.com <javascript:;>>
> wrote:
>
> > Hi Everybody!
> >
> > The Coco Cartridge Prototyping Pak PCB is designed and ready for
> > scrutinizing.  I'd like to get a few interested people to examine the
> > schematic and make sure I have done my homework correctly.
> >
> > The prototyping PCB provides for two types of address decoding using all
> DIP
> > style chips.
> >
> > The first type of decoding stays within the $FF40 - $FF5F addressing
> range
> > and decodes all the way down to a single byte.
> >
> > The Second type of address decoding allows for setting the base address
> to
> > any one of 8 blocks of 32 bytes in the $FFxx addressing block.
> >
> > There are four sets of jumpers that determines where the chip will be
> > addressed with only one jumper block/strap needed in any one set of
> jumpers.
> >
> >
> > SV1 selects which one of the 8 - 4 byte blocks in the 32 byte block you
> wish
> > to use.
> >
> > SV2 sets which 1 of 4 bytes of that 4 byte block you wish to use.
> >
> > SV3 if used will select which one of the 8 - 32 byte blocks you wish to
> use
> > in the $FFxx addressing block.
> >
> > SV4 selects which type of addressing you wish - The $FF40 - $FF5F
> addressing
> > range or The $FFxx addressing range.
> >
> > For most experiments, A 1 or 4 byte block is enough.  I just realized
> though
> > that if an 8 byte block of addresses are required, then a 2 to 4 decoder
> > will be needed to decode the A4 and A3 address lines with the output of
> SV3
> > connected to the active low gate input of a 74LS139 2 to 4 decoder chip.
> > There actually is a spare decoder on the PCB already which I could wire
> up
> > for this scenario.
> >
> > This should satisfy almost every address decoding scenario I can think
> of.
> >
> > Now for you guys to think of the impossible!  :D  When this has been
> > thoroughly scrutinized for errors, the boards will be available from
> OSHPark
> > for about $40 plus shipping unless we use a different PCB Fabrication
> house
> > which will require a big order to get the prices down similar to how the
> > N8VEM group gets there PCBs made.  If it wasn't for OSHPark's $5 per
> square
> > inch of board space charge, I'd use OSHPark for big PCB designs too and
> this
> > is what I would consider as the beginning of the Bigger PCBs.
> >
> > I'll be back online after a few hours to find out what everyone thinks
> of my
> > design.  Here are links to a rendering of the PCB from OSHPark.
> >
> >
> https://www.dropbox.com/s/yy17jwamkejx94s/Coco%20Cartridge%20Prototyping%20P
> > ak%20-%20Top.png?dl=0
> >
> >
> https://www.dropbox.com/s/euo6vq5ukkr8gvu/Coco%20Cartridge%20Prototyping%20P
> > ak%20-%20Bottom.png?dl=0
> >
> > If the links get split up on two different lines, just highlight both
> lines
> > and paste it into your browser.  I do it all the time.  The first link is
> > the top of the PCB and the second link is the Bottom of the PCB.  Any
> > addressing not needed of course does not need to be populated.  Have fun
> > folks and Take care my friends.
> >
> >
> >
> > Kip Koon
> >
> > <mailto:computerdoc at sc.rr.com <javascript:;>> computerdoc at sc.rr.com
> <javascript:;>
> >
> > <http://www.cocopedia.com/wiki/index.php/Kip_Koon>
> > http://www.cocopedia.com/wiki/index.php/Kip_Koon
> >
> > <http://computerpcdoc.com/> http://computerpcdoc.com/
> >
> >
> >
> >
> > --
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> > https://pairlist5.pair.net/mailman/listinfo/coco
>
>
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