Discrepancies between hel_gates_002 and hel_gfx_engine_040
mpark
Posts: 1,305
Can someone please explain the different values of LNTSC and SNTSC in hel_gates_002 vs hel_gfx_engine_040?
hel_gates_002:
hel_gfx_engine_040:
OK, 224 <-> 227, that's close enough, but 39 <-> 67 seems way off. Yet they both work -- how?
hel_gates_002:
LNTSC = 3584 ' NTSC color cycles per line (224) * 16 SNTSC = 624 ' NTSC color cycles per sync (39) * 16
hel_gfx_engine_040:
LNTSC = (227*16) ' NTSC color cycles per line (220-227) * 16 SNTSC = (67*16) ' NTSC color cycles per sync (39-44) * 16
OK, 224 <-> 227, that's close enough, but 39 <-> 67 seems way off. Yet they both work -- how?
Comments
Andre'
I see what you mean. As I increase SNTSC, I can get more and more sprites on the same scan line without the picture tearing, but the overall image on screen becomes narrower and narrower. And the picture becomes a little wavy. I think I'm beginning to understand.
Andre'