[Coco] NitrOS-9 newbie needs some help

[KnudsenMJ at aol.com]

In a message dated 8/9/04 11:34:23 PM Eastern Daylight Time, 
dgacke at ektarion.com writes:

> If this were true you ought to be able to see a deformed clock pulse 
>  using an oscilloscope. Have you or anyone else examined the clock lines 
>    under the conditions described above?

ISTR putting my O-scope on the SCS lead out the cartridge port, before and 
after removing those "government emission control" series R and shunt C.  
With the R/C removed, I saw a nice sharp rectangular negative pulse.  With 
those parts still in, it looked like a sagging bridge that barely touched bottom 
in the middle.

I don't recall ever scoping the RAM control leads or E and Q clocks, but the 
same probably applies.

ISTR that the proper, professional fix, that cuts the RFI emissions while not 
degrading the signal as you add more loads, is to replace the series R with a 
ferrite bead (inductor), and lose the shunt C.  Just thread the little bead 
ring on a short piece of wire that replaces the resistor.

BTW, RFI emissions aside (like trashing radio and TV all thru the house), 
having too sharp edges on the signals can cause ringing and reflections, which 
probably won't cause much trouble at our clock speeds, but just thought I'd 
mention that the swiftest, sharpest waveform doesn't always win.
--Mike K.