> It was impossible to change the program of an Intel 4004, the program was written in the ROM when the memory was manufactured. This is not accurate. If you u

> It was impossible to change the program of an Intel 4004, the program was written in the ROM when the memory was manufactured. This is not accurate. If you used a 4001 ROM as program memory, then it can’t be changed, but this is a property of the system, not the processor, and intel made the 4008 and 4009 memory interface chips to enable using standard RAM chips as program memory for the 4004. The 4004 also had a WPM (write program memory) instruction that could be used in these situations. I don’t understand why you are adamant the 4004 is not a microprocessor but the 8008 is. The 4004 is weird and clearly designed with some instructions specifically because it was targeted for a calculator, but that doesn’t mean it had “nothing to do with general-purpose programmable computers.” It was programmable and had a sufficient instruction set to be used for general purposes. Intel could have made a true fixed function chip just for the calculator, but they decided to made a cpu instead.