Re: "Mainframe Computer (not microprocessor), which has large instruction buffer to hold many instructions to be executed in the pipeline (assembly line). Multiple instructions are loaded from memory into the instruction buffer. Short loop is in Instruction Buffer.

How can one compare a microprocessor architecture with this very old mainframe architecture? Is this a bad joke?"

I’m not sure why you ask “how can anyone compare Microprocessors and mainframes”. As I’m sure you know, Mainframes were initially comprised of discrete components, SSI (small scale integration), MSI, and LSI devices. As chip fabrication technology advanced these bulky Mainframe components were compressed into GSI (gigantic scale integration) and Microprocessors. In some ways the only significant difference is that we can now fabricate devices with many more transistors in a very small space and thus we integrated many larger device into one smaller package.