Re: Apple II Video Generator

[Kevin <kevin@hackaday.com>]

> Thank you for demonstrating the screen of oscilloscope.  It appears to be IRE A, but not IRE B as I drew IRE picture earlier.

Correct

> The screen of oscilloscope does not look very clear.  Is it possible you can please zoom from 63 microseconds to 70 nanoseconds?  After 70 nanoseconds is reached, the square wave looks very clear.  The color burst is to be sine wave or triangle wave.

I will see what I can get, keep in mind my scope is from 1987, the color burst is a sine wave as you can see below

http://cheesefactory.us/apple2/PA200007.JPG

next is part of a "pixel" in low res mode, the dips you see is the shift register output clocking, but its way too fast for a NTSC based system to pick up, which is why it looks like a fuzzy square wave in my original pic

http://cheesefactory.us/apple2/PA200008.JPG

and a slightly more zoomed in version of the original pic

http://cheesefactory.us/apple2/PA200002.JPG

sorry for the fuzzy pic's I am in the middle of something so I am just holding the probe up to the video plug with one hand and snapping them with the other heh


> You are right as Apple II video DOES NOT generate luma wave *AND* chromosome wave.

let me confuse you some more

10 HGR2
20 HCOLOR = 2
30 HPLOT 0,0
40 CALL -3082
 
> Let's talk about luma wave while color burst is NOT enabled.
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> How do NTSC monitor interpret square wave into monochrome?  I suspect all 15 colors run at 7 MHz as true grayscale as monochrome.
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> If NTSC monitor's frequency is higher enough to sustain 14 MHz instead of 7 MHz, then grayscale does not show and true black & white monochrome shows.
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> Are you positive sure monochrome does not use luma wave?
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> What is the filter name do NTSC monitor use to display grayscale as monochrome?
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> Bryan