My Tandy Color Computer 3 had 512K (standard was 128K) and an 8-bit CPU (6809). It did have something akin to a MMU though (the GIME chip) - which paged the RAM

My Tandy Color Computer 3 had 512K (standard was 128K) and an 8-bit CPU (6809). It did have something akin to a MMU though (the GIME chip) - which paged the RAM in banks of 8K. As far as what it was used for - people mainly used it for RAM disks; it could also be used for page-flipping for the higher-res graphics modes the CoCo 3 supported. For the OS-9 Level II operating system, it was used much more efficiently to allow for larger (or more) programs to be multi-tasked, along with other uses. (for those unaware - OS-9 was a multi-user, multi-tasking operating system for the 6809 and other 8-bit microprocessors of the day - but mainly geared to Motorola CPUs - including later the 68k family)