@g0c001: Welcome to TinyCore!
Without knowing the model number I cannot pull specs on the machine, but can advise a plan of attack to narrow things down.
If you're still running Windows on the hard drive and WISH to continue doing so, write down everything you change in case you need to reverse the process.
You must also understand that by making changes to BIOS
COULD make it impossible to revert back, but due to the age of the machine, that's not as likely.
BEFORE doing the following, check
this page on HP's website for further details.
- While the machine is first starting up, repeatedly press [F10] to go into BIOS (settings)
Depending on the configuration, you may need to use [FN]+[F10] if that didn't work. - You'll need to look around BIOS for SECURE BOOT ("EFI" or "UEFI") and DISABLE it
- Now try to boot using the TinyCore USB device you created.