Some (but not all? not many?) computers can boot from a compact-flash attached via the PCMCIA port.
Niggling details to deal with:
- the CF card has to be marked as a "fixed disk", instead of "removable". Some cards are able to be configured this way, but many aren't.
- the BIOS has to support booting via PCMCIA-attached hard drives and/or CDROMs
- note: however, there are workarounds if this isn't the case
- getting the disk geometry correct can be fiddly