floppy disk-based train control system

Floppy discs still run a U.S. metro? Japan steps in with 'project kill
floppy'

Hitachi Rail contract inked by SF transport board will kill the
throwback

San Francisco's Muni Metro could be finally getting ready to wave
goodbye to the antiquated and archaic floppy disk-based train control
system.

Yes, we're talking about the good old 5.25-inch floppy disk, which is
somehow still being utilized for something as important as a critical
function of a public transport network within a major city. In a move
that many are wondering why and how it took this long to get around to
it.

https://www.theregister.com/2024/10/24/hitachi_rail_contract_san_francisco/

5.25-inch floppy disk

That's how I booted up an IBM PC (Intel 8088 @ 4.77 MHz) years ago

IIRC, a few years later, I bought a 32 meg hard drive for some $300.00