Computers were large and cumbersome when we were in high school, but most large companies had them. Smaller companies purchased services from data processing companies. Mainframe time costs more per hour (in nominal dollars) than a laptop costs today, and had only a fraction of the processing power. And today's software is miles ahead of yesteryear's.
"Say, Bob, can you please mount the FORTRAN 66 compiler?" “And today’s software is miles ahead of yesteryear’s.”
Most of it is not.
log ago software was written by very smart people who had to optimize it properly, and they did
Today everything is a bloated slow gui mess, and likely uses lots of libraries. (java .net etc)