<span><span>Computer architecture was essentially a contract with software stating unambiguously what the hardware does. The architecture was essentially a set of statements of the form "If you execute <span>this </span>instruction (or get an interrupt, etc.), then that is what happens." <More sophisticated readers: I get to the term "ISA" later.>
</span><span>Computer organization, then, was a usually high-level description of the logic, memory, etc., used to implement that contract: These registers, those data paths, this connection to memory, etc.
</span></span>Computer Architecture and Computer Organization Examples
<span>Intel and AMD make X86 CPUs where X86 refers to the computer architecture used. X86 is an example on a CISC architecture (CISC stands for Complex Instruction Set Computer). CISC instructions are complex and may take multiple CPU cycles to execute. As you can see, one architecture (X86) but two different computer organizations (Intel and AMD flavors).
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nVidia and Qualcomm on the other hand make GPUs (graphics processing unit as opposed to a CPU central processing unit). These GPUs are based on the ARM (Advanced RISC Machines) architecture. ARM is an example on a RISC architecture (RISC stands for Reduced Instruction Set Computer). Instructions in an ARM architecture are relatively simple and typically execute in one clock cycle. Similarly, ARM here is the computer architecture while both nVidia and Qualcomm develop their own flavor of computer organization (i.e architecture implementation)</span></span>
