Problem with vertical shifting

[joelm]

Hello all, I am new here so please be patient, I'm sure I must have missed something minor.

 

I have been writing the example code from the sessions myself (so I can learn the flow of logic) but, except for the notes and some spacing, have been copying them more or less verbatim. My issue is that whenever I introduce anything horizontal in the code the screen seems to rollover (and flicker) when I run the binary in Stella. For example any change in the background color or any horizontal playfield (lines on the side of the screen work fine). A plain background with no horizontal images works fine with no rolling or flickering. In the initial playfield lesson a basic binary counter playfield was introduced with a rainbow background, my rainbow background rolls rapidly and is verging on headache or siezure. I will include my code (both asm and bin) so you can take a look to see if I am doing anything wrong.test.zip

[RevEng]

Your VSYNC code is off. The part that currently reads...

 

					lda #0
					sta VBLANK

					lda #2
					sta VSYNC

					sta VSYNC
					sta VSYNC
					sta VSYNC

					lda #0
					sta VSYNC

 

...should read...

 

					lda #0
					sta VBLANK

					lda #2
					sta VSYNC

					sta WSYNC
					sta WSYNC
					sta WSYNC

					lda #0
					sta VSYNC

 

...so you turn on VSYNC, draw 3 lines with it on, and then turn it off.

[joelm]

Awesome. I knew that I had missed something obvious. Becuase of my work schedule I am learning to do this between 1 and 2 am after a 12-14 hour workday... I guess I just wasnt seeing it. Thank you.

[RevEng]

Not a problem, and welcome to AA!