What are CPU designs which are not fetch/store but operate directly on RAM?
I only know about the design of the Nintendo Entertainment System (NES), where the CPU does not have registers (AFAIK) and operates directly on RAM, with fast access to low addresses in the RAM.
What CPUs/Systems do you know, which also do not do fetch/store for their operands? Which systems are out there? Why do CPUs like RISC/Arm/AMD64 use fetch/store, what are the tradeoffs? Are there different architectures for CPUs working on operands outside of fetch/store, DMA and stack machines?
Just to be more specific, from your link the operations with operands from low registers “zpg zeropage OPC $LL operand is zeropage address (hi-byte is zero, address = $00LL)” looks like exactly the stuff I am interested in. It seems to me, that they are like 256 (slower) pseudo registers.
Ah, I see what you mean now. Yeah I’m guessing there are code sequences where it’s more efficient (either in clocks or code size or simple convenience) to operate on these 256 low addresses than repeating load/hit/store.