Or you dual-port the VRAM. Or you have a division between RAM banks managed by the OS, e.g. “slow” and “fast.” Or you have the custom chips mediate access to th

Or you dual-port the VRAM. Or you have a division between RAM banks managed by the OS, e.g. “slow” and “fast.” Or you have the custom chips mediate access to the VRAM entirely, but offer a DMA feature for, say, block transfers of bits. Or… There are lots of ways to support a full 640×480—or more—with an 8MHz 68000. Sun, Apollo, and HP all supported at least 1024×768 on their 68000/68010 workstations.