If you REALLY want to see how far we’ve come, check this out!
ZX81 emulator. In a webpage. Yes, my first computer is so small these days that it can be carried along as an accessory to a page of text.
Ref Derleth’s post … yeah, retro is tab machines or 360s for big iron, and cp/m for small machines. FOCAL on PDP-8s brings back memories.
For the OP: My last Macs ran 6.1. and that was an upgrade from what they shipped with. “Surfing” was still some ways in the future at that time, although you could get a modem & comm software to use BBSes and something vaguely like IRC whose acronym I can’t quite dredge out of the ol neuron bank right now.
How far we’ve come. Last week I was given a branded tchotcke at a Microsoft promotional event. It was a ball point pen with a laser pointer and a 2GB thumb drive built in. I recall working on machines where 2GB of disk drive could be attached, but that humongous amount of storage took up about a 1-car garage’s-worth of floor space and the cabinets were head high. The power cable was the size of your forearm. They also cost ~$250K per 200MB (IBM 3330 for those who knew).
IOW, what cost 2+ million dollars when I was in college is now a party favor.
Well, that’s more retro than Macs running System 8. People calling those things retro just makes me feel old. 
And the thumb drive contains a microcontroller more capable than the CPU a mainframe of that era had, too, I’m pretty sure. In short, it’s theoretically possible to emulate a 1970s-era mainframe on a device that will fit in your pocket and is cheap enough to just give away, and the resulting system would be faster and possibly have more storage than any real example of what it’s emulating.
This probably a bit of a stretch - the 360-195 could do around 10MFLOPS, and since the microcontroller on your USB stick is unlikely to have an FPU, it’s not going to do very well in this benchmark. Still, it’s pretty amazing how much computing power we take for granted (and how much real work could be done with machines barely more sophisticated than an adding machine).