HOw do scanlines work, meaning how can implement them on the screen for scrolling text? Im looking over Nesasm and ran into this code:
What is going with the EOR #1?
How does LDA $#40 start 2 tiles down scan line 16?
How do tiles coinside with scrolling on the scanlines?
Can someone please go into detail on what going on.
Also, does anyone have any of there own scrolling text code i can experiment and study with.
Thanks in Advance,
EL
Code:
print_message:
lda msg_nt
eor #1 ; Invert to draw to the nametable that isn't shown atm
asl A ; Multiply by 4
asl A ; ...
ora #$20 ; OR with $20 to get either $20 or $24
sta $2006
lda #$40 ; Start 2 tiles down (scanline 16)
sta $2006
lda msg_nt
eor #1 ; Invert to draw to the nametable that isn't shown atm
asl A ; Multiply by 4
asl A ; ...
ora #$20 ; OR with $20 to get either $20 or $24
sta $2006
lda #$40 ; Start 2 tiles down (scanline 16)
sta $2006
What is going with the EOR #1?
How does LDA $#40 start 2 tiles down scan line 16?
How do tiles coinside with scrolling on the scanlines?
Can someone please go into detail on what going on.
Also, does anyone have any of there own scrolling text code i can experiment and study with.
Thanks in Advance,
EL