How does an arduino microprocessor compare to some of the older computers in RAM, and computational speed? Like how does it compare to the Intel 400 or the original IBM PC. I'm interested in both the Atmega328 and the 2560. Just how much better/worse is the arduino compared to an old computer?
Similar capability in turns of processing power if you compare back 10 -20 years.
arduino is a micrcontroller not a microprocessor.
A good example is the pdp11 minicomputer and the ti msp430 micro controllers. They share the same instruction set (approx 90%) . Both can (or could) do realtime event handling but pdp11 was more for data processing. Though pdp11 didn't have integrated peripherals
see bottom of this page http://www.cpushack.com/CPU/cpu4.html
The Arduino chip (usually Atmega328p-pu) is an AVR (Advanced Virtual RISC*)!!! It doesn't processor but a "full functional nano computer" a Microcontroller! The characteristics of Atmega328P-PU is an 8bit CPU with 2Kb RAM**, 1Kb ROM*** and 32Kb Flash. The CPU's max speed is 20 MIPS @ 20 ΜHz, double of Motorola 68020 (1988) and the half of ARM7 (1994) more fast than Intel i486DX (1991). ***electrically erasable Programmable ROM **synchronous RAM or SRAM yes! is a type of RAM *RISC=Reduced instruction set computer https://www.microchip.com/wwwproducts/en/ATmega328P https://en.wikipedia.org/wiki/Instructions_per_second