[chaimanmeow]

Needs a bit more proofreading but nice to read anyway.

This might need major fix

> In a 64-bit ISA, each instruction is represented using 64 bits (8 bytes).

Not as I understand it and maybe only for exotic ISAs like VLIW. For most other, CISC or RISC, I think the instruction length might be much smaller, and in some cases, x86 for example, the length of instructions is variable (one of the reasons they have a decoder). The size of the registers is 64 bits, as are the ALU operations on these registers, and the length of the words that are addressed in memory.