[Coco] Coco Cartridge Prototyping Pak PCB

[lciotti1]

Also the ICs on the bottom look too close the the edge of the board.

> Brian Goers <mailto:briang0671 at sbcglobal.net>
> October 8, 2014 at 9:38 PM
>
> On the top drawing. I see an outline around two holes, are the two 
> holes connected.
>     I would like to have at least 3 holes connected.
>
> The outline pattern changes to the right of the decoding section, it's 
> one row down.
> The outlines do not line up from the left to right across the board.
>
> Can numbers be put on the board to help layout/ locate positions?
>
> How big is this board?
>
>
>
>
> Kip Koon
>
>
> Kip Koon <mailto:computerdoc at sc.rr.com>
> October 8, 2014 at 6:20 PM
> 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> computerdoc at sc.rr.com
>
> <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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