I seem to remember it was the 10 meg drives
The 10 Mb drives from seagate that were sold as upgrades and replaced one of the floppy drives. They were also sold with new systems (both IBM PC XT and various clone systems). It's been a long time though and my memory has holes like a swiss chees.
"When it crosses my mind to do something, I don't ask why, I ask why not. And usually there's no reason not to, so I just go ahead. It's given me the strangest collection of hats"