That wasn't usually a timing problem, though there were programs that broke if you added more RAM. The original Amigas (A1000 and A500) only had "Chip RAM", IE

That wasn't usually a timing problem, though there were programs that broke if you added more RAM. The original Amigas (A1000 and A500) only had "Chip RAM", IE memory that the custom processors could access. Today we'd call it Video RAM, except that it was also directly addressable by the CPU. Later, we got "Fast RAM" that was faster (hence the name) but only usable by the CPU, not the custom chips. Some badly written programs assumed any RAM they found could be used for anything. And then they blew up when they loaded something past the bottom 512K (or 1MB or 2MB depending on the model) and told the blitter or copper to use it. As another poster mentioned, it wasn't really a huge problem. Most programs were written correctly before Fast RAM was common, and afterwards, everyone knew about the issue. A bigger memory related problem was that the original 68000 CPU had no MMU. The system APIs (for apps that weren't written to the bare metal) included the idea of shared and private memory. But on the 68K it didn't actually make any difference, it was all one big flat memory space addressable by every process. Later, on the 68020 and up, a real MMU was available, but so many programs had been written to just allocate everything in public memory that it was impractical to actually use that MMU properly. That's a major reason the OS never got real virtual memory despite having hardware that should have been capable of it on later models. Having dual-booted NetBSD on an A3000 for a while, my first Unix system at home, I can vouch for the hardware working properly.