[Coco] 6 Chip 6809 Computer - Final Design, Hopefully

[Joe Grubbs]

Nevermind, might have an FJN3301R transistor (built-in bias resistors). That and a 1K resistor should take the place of a single NOT gate. And I could just tack those onto the board. Unless of course you wanted to make space for a more readily available BJT (2N4401 or something) and a couple resistors ;)



From: jsgrubbs at hotmail.com
To: coco at maltedmedia.com
Subject: RE: [Coco] 6 Chip 6809 Computer - Final Design, Hopefully
Date: Tue, 10 Mar 2015 13:10:41 -0400




Hi Kip,

If I wanted to use Grant's trick of enabling hardware flow control, is there space for the 74LS04 he recommends? I'm guessing no. In lieu of that, could I make a simple discrete NOT gate, maybe from a JFET or couple BJTs and cram it onto the board between the appropriate pins of the uart and max232?



> From: computerdoc at sc.rr.com
> To: coco at maltedmedia.com
> Date: Mon, 9 Mar 2015 21:57:01 -0400
> Subject: [Coco] 6 Chip 6809 Computer - Final Design, Hopefully
> 
> Hi Guys,
> 
> I have what I believe will be the final design for the 6 Chip 6809 Computer
> v1.0.  Grants original design had every input tied high.  With the requests
> to have an expansion bus, I put my Kipper Bus on the PCB and put 1K pull up
> resisters on all inputs to the 6809 processor.  This design is an excellent
> first single board computer project for someone who has never made a little
> PCB computer.  However, I feel the design is a bit restrictive for a more
> capable single board computer or a CPU board to be used as the basis of a
> multi-board computer.  With that being said, I am quite interested to see
> what you guys come up with.
> 
> Here are the pdfs of the design as it currently stands.  I finished it this
> afternoon.  Please let me know your thoughts, suggestions, ideas for future
> versions, etc.
> 
> This is the main schematic.
> 
> https://www.dropbox.com/s/dx7wvrpkk7qzabm/Grant%27s%206-Chip%206809%20Comput
> er%20-%20Exactly%20Like%20The%20Original%20Design%20tighter%20layout%20Kippe
> r%20Bus%20sch.pdf?dl=0
> 
> This is the power rails and DC input schematic.
> 
> https://www.dropbox.com/s/avjexzf88bghgxe/Grant%27s%206-Chip%206809%20Comput
> er%20-%20Exactly%20Like%20The%20Original%20Design%20tighter%20layout%20Kippe
> r%20Bus%20sch%202.pdf?dl=0
> 
> This is the PCB Board layout.
> 
> https://www.dropbox.com/s/gj1k632ktzlhyfs/Grant%27s%206-Chip%206809%20Comput
> er%20-%20Exactly%20Like%20The%20Original%20Design%20tighter%20layout%20Kippe
> r%20Bus%20brd.pdf?dl=0
> 
> I think this will be the design I make the first prototypes with unless
> anyone finds a problem that needs correcting.  Just let me know if you find
> anything.  I'd like to go ahead and build a prototype as soon as possible.
> 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
> 
>  
> 
>  
> 
> 
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