I agree with those that say it is BS. Our motion controllers have more memory than the PLCs that control them. Memory is cheap. The problem is retaining it during power off situations. In our case we have a special memory that keeps retained memory but we cannot retain all of the memory. We have 1MB allocated to the program memory alone.
Our new RMC200 has 16 MB reserved for curves or cam tables. We have over 12M 4 byte entries for capturing data.
I think we have a total of 256MB of ECC ram. ECC is the kind of ram that Xeon processors must use. ECC ram will correct errors.
What we have found over the 30+ years of making motion controller is that ram gets cheaper and cheaper and bigger and bigger. Todays small rams will be as expensive or more expensive than larger rams because of lack of demand. It makes no sense to skimp on ram.
I read something about lack of address lines. That isn't a problem with modern CPUs.
BTW, we have had many more problems with static rams than we have had with dynamic rams.