If you just need to test if a port is open or send a few commands, you might not need to download anything.
HyperTerminal wasn't an operating system; it was a piece of software, specifically a stripped-down, licensed version of Hilgraeve's HyperTerminal Private Edition . It shipped with Windows 95 through XP. Its job was simple yet powerful: to let your PC talk to "other things" over a serial cable, a modem, or a null-modem cable.