1MB Playstation Memory Card

I think it was 1997 the playstation came out and thats when i got it. I also paid either £14.99 or £19.99 for the first memory card. The memory card had 15 slots on it. So i thought this meant it could hold 15 different games but i was wrong. Fair enough some games only used one slot, but i started getting games that took up ten slots. Later games made would take up more than 15 slots. So haveing a memory card of this size wasnt any use. After this memory card other ones were made. They kept getting bigger and bigger in size. I think the biggest memory card made could hold 1000 slots or a few hundred. Maybe someone could share some light on the size of ...