When I was in high school in 1999 I worked for a guy that drove around a motor home "fixing computers" which was basically a mobile virus scan and removal operation.

I guess there was the internet then, but it was still very, very limited. A lot of people didn't have it.

I got the first virus on my computer before it was internet connected. Instead it was from a floppy disk from a friend. It took days, and days to figure out how to remove it.

A market without the Internet would probably not be the right one. :-)

Viruses were widespread on platforms like the Commodore Amiga well before the wide-spread adoption of the internet.

How did they spread?

exchanging floppy disks via mail

floppy disks

That's what Iran thought too. :-)