Firmware 3.10: Some fast loaders fail

[SaxxonPike]

System: Cartridge - 1541 Ultimate II+ C64 - 6510 CPU, 8562 VIC-II (NTSC) Stock KERNAL, drive ROMs

Fast loaders that seem to fail at some point during load: n0stalgia - Legacy of the Ancients: Fails at blue LOADING screen before the title screen ESI - Legend of Blacksilver: fails on load after the title screen

Standard KERNAL loads work fine. Most games work fine. It seems when we start uploading custom code to the drives is when issues arise. I flashed back to 3.9 and these loaders seem to work fine with the exact same setup.