[stella] TIA input pins 12 and 8 on PAL chips

Subject: [stella] TIA input pins 12 and 8 on PAL chips
From: "Matthias Hartl" <maze@xxxxxxxxxxxxxx>
Date: Wed, 27 Nov 2002 23:35:23 +0100
Ok, this is question is not related to programming the Stella chip, but I hope someone is willing and able to answer it anyway. I'm currently assembling my own ATARI 2600 clone wit a PAL version of the TIA chip. Everything works fine so far (black & white). In order to get some color onto my tv screen, I have to apply a certain "signal" to pin 8 and 12, labeled as PALS and PALI in the schematics found at atariage.com. My humble electronic skills tell me this is some kind of sine wave at a frequency of 4,43MHz. Is this right? How does the TIA do the necessary phase shift in order to encode the color information?
I would be very glad, if someone could spread some light on this. Thank you in advance!
Matthias Hartl (Germany)
Current Thread