Here's a few: 6502: 8-bit registers / 16-bit address space (1975-) 68000: 16 / 24 (1985-1992 then 32/32) ARM1: 32 / 26 (1985- 32/32 in 1992 and finally 6

Here's a few: 6502: 8-bit registers / 16-bit address space (1975-) 68000: 16 / 24 (1985-1992 then 32/32) ARM1: 32 / 26 (1985- 32/32 in 1992 and finally 64/64 in 2011) X86: a complete address space mess but lately 57-bit: https://en.wikipedia.org/wiki/X86 https://en.wikipedia.org/wiki/X86 The morale of the story is humans are insecure fragile little creatures, half of us are blind and the other half are pessimists because we can imagine what the truth/future looks like. Lies only last the time you can use energy to hide them. Anyhow the arch of binary evolution is over; to build a MMU that can adress 64-bits of data is probably impossible with electrons. Just going from 64GB to 256GB is hard and makes things slower! Caches appeared in 1985, so since then the bottle neck has been RAM latency: https://gettotext.com/largest-ram-bar-in-the-world-consumes-80-watts/ https://gettotext.com/largest-ram-bar-in-the-world-consumes-... The biggest server from Oracle currently has 16 TB of RAM, good luck multiplying that by the difference in energy content per mass difference between oil and uranium (1.000.000x). And good luck paying your energy bill. 64-bit RAM would consume 5120W * 1.000.000 = 5GW (you want 5x nuclear power plants with that server?) Personally I'm staying on 32-bit for my ARMv8 cluster, my processes are limited to 4GB RAM each but since I only have 8GB of total RAM there is ZERO difference in switching to 64-bit as it effectively halves the RAM.