[Coco] RE: [Color Computer] Opinion time

[Gene Heskett]

On Sunday 09 April 2006 11:24, RJRTTY at aol.com wrote:
>In a message dated 4/9/06 10:47:48 A.M. Eastern Daylight Time,
>
>gene.heskett at verizon.net writes:
>>Thanks for the link.  Those shots are MUCH MUCH sharper  than I can
>> do. I've looked at things here and found that as  applied to the
>> adaptor Roy sent me, the high freqs are very badly  rolled off, so
>> much so that 80 column text, particularly in color  combos using
>> blue aren't well reproduced as the rise times to give  those nice
>> sharp pix you are getting just aren't there coming out of  my coco3.
>>  A full black to white transition is well over 280ns  here.
>
>Gene
>    What value of resistor are you using to set input  impedance
>on your converter.   I have found that 50 ohms is best.

Since it was video, and all video uses 75 ohms, thats what I used.

>It 
>really improves the black on red and black on blue for
>foreground/backround color combinations.   That's the
>value I am using in the units I send out now.  I am also
>considering droping the bottom bits on the ADC to try
>decrease the resolution of the converter and block
>out some of the faint backround artifacts the GIME
>outputs.

I wondered about that myself.  But then one needs to trim the gain to 
put the normal britness levels for half and full in the middle of the 
deadband so caused.  We're doing that now anyway, but...

What sort of rise & fall times are you getting at the gime outputs?
>
>Roy

-- 
Cheers, Gene
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