[Coco] RE: [Color Computer] Opinion time

[RJRTTY at aol.com]

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.   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.
 
Roy