[Coco] An 8-Slot Multi-Pak Design for my Color Computer Friends

[Gene Heskett]

On Sunday 04 July 2010, jdaggett at gate.net wrote:
>First
>
>A huge mistake in not buffering the data bus on the main board. If you are
> running a stock Coco3, you do run the risk of damaging the MC6809E and
> the HD6309E if the board becomes detached while powered up.
>
>Second
>
>why the dip switches on the Control and clock lines. A wrong setting on
> the dip switches and you have a nonfunctioning board that can lead to
> frustration.
>
>Third
>
>What is the function of Q1?
>
>Fourth
>
>Your ground plane on the top and bottom are basically floating planes that
> are tied at but just a few spots. You have all your locic tied to GND1
> and then this large plane on both sides is GND. You also have fingers
> that are floating that is bad for noise immunity. Either use one ground
> or tie them in a star pattern and eliminate the floating fingers.
>
TBT, the shacks own design re the ground plane sucks, big time.  I had to 
add more bypassing and lots of 12 gage solid jumpers to get the ground 
bounce down to the no error levels in my mpi.  I started with about 2 volts 
in the middle of it, referencing the clip ears on the coco's motherboard.

>just a few things I see wrong or bothersome.
>
>By the way I have a degree in Electrical Engineering and have 23 yrs
> experience in PC layout and design of portable electronics. SO these
> questions do come from someone that has experience and questions about
> the design.
>
>james
>
>On 3 Jul 2010 at 18:12, Little John (GIMEchip.com) wrote:
>> This is my latest project, designed just for you guys and the readers of
>> CoCo3.com. I worked on this for about 9 hours when my internet was off.
>> Hopefully it will be of some use to some of you.
>>
>> It is taking a lot longer to do the write up than it did to complete the
>> design, but I have posted Part 1 (of 2) here:
>> http://www.coco3.com/community/2010/07/this-is-part-1-of-2-of-an-8-slot-
>>mpi-multi-pak-interface-design-for-my-friends-at-coco3-com-andor-the-malt
>>edmedia-list-members-from-your-friend-johngimechip-com
>>
>> Let me know if you spot any potential problems. I'll get part two typed
>> up and posted by tomorrow.
>>
>> Enjoy. Let me know if you find any errors in my design. I'll fix any
>> that crop up.
>>
>> Your Friend - Lil' John
>>
>> --
>> Coco mailing list
>> Coco at maltedmedia.com
>> http://five.pairlist.net/mailman/listinfo/coco
>
>--
>Coco mailing list
>Coco at maltedmedia.com
>http://five.pairlist.net/mailman/listinfo/coco
>


-- 
Cheers, Gene
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