Question

which invension led to the evolution of second generation , third generation and fourth generation computer

Answer 1

Memory is what allows a computer to remember things. Similar to human memory, there's long term memory (a hard disc or optical media (like a CD)) and short term memory (RAM). When a computer is turned off, it forgets everything in the RAM, so the computer saves everything it knows it will need later on in the long term memory. The short term memory is easier to use because it can do I/O faster, so when a data is needed by the CPU, it's sent from the hard disk drive (HDD) to the RAM.