Hi all,
I'm building a budget Apple IIe/IIc VGA card that most people will be able to put together by themselves.
https://lukazi.blogspot.com/2023/05/a2vga-pico-iie-card.html.
I'm trying to cement which video signal pins to be used before I build the next revision of the hardware. I prefer to get this correct now then find a surprise later.
From the IIe Aux port or IIc Video port - Pins needed:
14M: Apple II video clock
SEROUT : Luma part of the video signal ie the monochrome pixel bitstream.
WNDW: Start of the picture being displayed.
Pins also included:
GR: Sets up each line to display in colour or monochrome.
Pins considering:
SYNC: Start of line at the left hand border. May become useful for VSync. Alternate to WNDW signal.
LDPS: Helpful to realign 80 and 40 column modes.
VIDD7: Can be used to implement Combined Colour/Mono mode (was popular on RGB cards). I've just posted details with pictures on this signal here
https://www.applefritter.com/content/apple-ii-video-hdmi-using-raspberry-pi-zero-pico.
Pins excluded:
CREF: Colour reference. Great for discrete component based video cards but not required on microcontroller based video cards since CREF is just 14M/4.
For those who have done Apple II video stuff before, is there any other signals which you have used/considered and why?
Thanks
Alex.