I replaced PLA to this c64 with a modern rom. Now it seems to work fine beside of this wired colors. Messing with ct1 (the trimmer near the Vic II) causes the
Sostituire PLA con eprom
C64 PLA implemented in VHDL
PLA (C64 chip) - C64-Wiki
C64 PLA implemented in VHDL
Commodore 64 PLA C64 SX-64 Replacement 906114-01 251064-01 8700-001 GAL Based - Etsy