Re: Apple II Video Generator

[Immortal Nephi <Immortal_Nephi@hotmail.com>]

On Saturday, October 20, 2012 5:02:49 PM UTC-5, Kevin wrote:
> My scope is almost as old as my apple, but here is what I did... I used the following script to create a low res grid on the apple 2 10 GR 20 COLOR = 7 30 FOR Y = 0 TO 39 STEP 2 40 FOR X = 0 TO 39 STEP 2 50 PLOT X,Y 60 NEXT X 70 NEXT Y and here is a picture from the scope http://cheesefactory.us/apple2/PA200009.JPG hope it helps

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

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.

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

Let's talk about luma wave while color burst is NOT enabled.

How do NTSC monitor interpret square wave into monochrome?  I suspect all 15 colors run at 7 MHz as true grayscale as monochrome.

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.

Are you positive sure monochrome does not use luma wave?

What is the filter name do NTSC monitor use to display grayscale as monochrome?

Bryan