So, I began implementing scrolling to replace just simply showing a nametable with sprites on it. After awhile, donkey kong continues to run and a lot of test roms continue to function, but now some test roms and mario flash and then blank out.
So, for example, blaarg's test roms, for example on testing vblank (01-vbl_basics), I will see the text flash momentarily and then blank out. I can see that the nametable has the valid data. And looking at $6000 shows that the test passed. But nothing is showing on screen. Again, donkey kong runs, other single screen roms like balloon fight run. But these test roms and mario simply do not.
In the source code for 01-vbl_basics, I see blaarg's code do this:
lda #0 ; BG off
sta $2001
Which indeed would turn off background rendering. However, nothing I see in the code turns it back on again. Am I missing some other operation triggering background rendering again?
Thanks for any thoughts! Boggling me.
So, for example, blaarg's test roms, for example on testing vblank (01-vbl_basics), I will see the text flash momentarily and then blank out. I can see that the nametable has the valid data. And looking at $6000 shows that the test passed. But nothing is showing on screen. Again, donkey kong runs, other single screen roms like balloon fight run. But these test roms and mario simply do not.
In the source code for 01-vbl_basics, I see blaarg's code do this:
lda #0 ; BG off
sta $2001
Which indeed would turn off background rendering. However, nothing I see in the code turns it back on again. Am I missing some other operation triggering background rendering again?
Thanks for any thoughts! Boggling me.