Here's the OS 1.20 code for *FX19 in TobyLobster's disassembly:So it looks to me as though it should always wait at least one VSYNC.
Code:
.osbyte19EntryPoint LDA .verticalSyncCounter ; Read vertical sync counter- CLI ; allow interrupts briefly SEI ; disable interrupts again CMP .verticalSyncCounter ; has the vertical sync counter changed yet? BEQ - ; if (the values are the same) then branch (loop back)Statistics: Posted by SteveF — Mon Sep 09, 2024 9:01 pm