Even without address translation hardware, it is not necessarily the case that the machine's "bit width" defines the maximum RAM address. Example: The CDC "upper 3000" series were 36-bit machines. Do you think they could address 64 GiB of RAM? Not hardly! Those machines came out in the mid-60s! Heck, we couldn't even have 64 GB of disk space in those days. (The CDC 6000 series were 60-bit machines. Need I go on?)