How did stock trading work in the early-to-mid 90s?

Quick preface; I have essentially zero knowledge on stocks/markets.

I'm trying to do some research into the stock market of the early 1990s for a personal project of mine. I tried to google various questions but all i get are reports of the market and other various news from the time.

I have read that an online communication system was introduced around 1975, and that buying over phone was a large practice before the stock market crash – wherein priority was introduced for smaller tradings.

What i'm specifically looking for though, is how someone would buy/sell stocks in 1991-1997. Would it be over the phone, using one of a few regulated websites, etc?

Another related question – could people in other countries, like England, purchase American stocks back in the early 90s?