[Coco] TC-9

[LinuxRules]

jdaggett at gate.net wrote:
> On 7 Jul 2008 at 22:13, Chuck Youse wrote:
>
>   
>> On Mon, 2008-07-07 at 21:49 -0400, jdaggett at gate.net wrote:
>>
>>     
>>> The only analog functions are the composite video from the internal
>>> DAC the RGB DAC and the oscillator circuitry on board. The
>>> oscillator and its quadrature phase is rather easy to do in an FPGA
>>> given the modern DLL/DCM in most chips. 
>>>
>>>       
>> The composite signal by itself will be a bitch.  And don't forget the
>> drive requirements on the E clock.  Anyway, the point is it'd require
>> external components, an FPGA alone won't suffice, but I think we agree
>> on this point.
>>
>>     
> ------------------------
>
>  Yes it is but is doable. The MC6809 with internal clock, the E and Q clock 
> source current is 2 mA. The chip is depletion load NMOS technology. I am 
> not sure of the geometry of the output transistors on teh clock. The spec is 2 
> mA so they may very well be NMOS and not bipolar. 
True.
Being an ex-Mot guy from that group at that time, we had no bipolar 
"recipes" available
to the MPU/MCU designers. Everything was Dep Loads (and d at mn glad to 
have 'em!)
until the 146805 7 146818 came along.
[6800(redesign), 6801/02/08, first 6805s, 6809, et al.......]

Been lurking for a while, and I'm blown away by the talent demonstrated 
here.
Sure wish we had had some of you folks back then!!!
cheers,
johnd