[Coco] Grant Searles SBC

[Bill Nobel]

Well I do have extra Eproms to try that.  I am still thinking I have a timing issue to the 6850.  I need a scope……

Bill Nobel

> On May 6, 2015, at 8:51 PM, Zippster <zippster278 at gmail.com> wrote:
> 
> Hmm, at this point I might write a quick assembly program that inits the serial chip and
> just outputs one (known) character to it in a constant loop, burn that to a ROM,
> and start probing address and data lines just to see if valid data is making it that far.
> 
> - Ed
> 
> 
>> On May 6, 2015, at 9:27 PM, Bill Nobel <b_nobel at hotmail.com> wrote:
>> 
>> I am using tantalums on the charge pumps. and electrolytics currently for the decouplers. i can change the decouplers to tantalums as I have enough in stock.  I have a bunch of ceramics coming for the decouplers, as I had the same thought for that reason.
>> 
>> Bill Nobel
>> 
>>> On May 6, 2015, at 8:15 PM, Zippster <zippster278 at gmail.com> wrote:
>>> 
>>> I would normally go with .1uF ceramics, 1 per IC, perhaps 2 on  the CPU.
>>> 1uF or slightly larger decoupling on the MAX232.
>>> 
>>> Are you using tantalum caps for the charge pumps on the MAX232?
>>> Some versions can use ceramics as well.
>>> 
>>> - Ed
>>> 
>>> 
>>>> On May 6, 2015, at 9:03 PM, Bill Nobel <b_nobel at hotmail.com> wrote:
>>>> 
>>>> Yes I do. I am use 1uf caps right now, should I use maybe .1uf instead?
>>>> 
>>>> Bill Nobel
>>>> 
>>>>> On May 6, 2015, at 8:00 PM, Zippster <zippster278 at gmail.com> wrote:
>>>>> 
>>>>> I would think you would be ok as far as bleed over, although you could try separating them a bit.
>>>>> Breadboarding always makes me wonder if I’m getting reliable contact with everything.
>>>>> 
>>>>> Do you have decoupling caps on all the chips, including the MAX232?
>>>>> 
>>>>> - Ed
>>>>> 
>>> 
>>> 
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