Download Old Firmware Files of Pentax DSLRs from the Pentax.jp Server (and Do the Downgrade)

I can see occasionally some Pentax DSLR users want to download the older firmware and program it back into their bodies for whatever reason(s) of their own. But the first thing they have been asking is where to get and download the older version(s) of the firmware?Actually, most of those are still kept at the Pentax.jp server, just do it this way:-1. The current and latest firmware is linked in