Not Fast RAM, but Slow RAM.
Fast RAM is exclusive to the CPU. On A500, it needs to be on the CPU socket, or on the left expansion port.
Trapdoor RAM, as in the common 512K expansion, can only be Slow or Chip.
Slow because the chipset can block access to it, but can't access it itself.
Chip on newer A500 boards with ECS Agnus, after a small motherboard jumper mod.
Not Fast RAM, but Slow RAM.
Fast RAM is exclusive to the CPU. On A500, it needs to be on the CPU socket, or on the left expansion port.
Trapdoor RAM, as in the common 512K expansion, can only be Slow or Chip.
Slow because the chipset can block access to it, but can't access it itself.
Chip on newer A500 boards with ECS Agnus, after a small motherboard jumper mod.