what does the other end of the white cable on the front of the processor connect to? ...
if you're lucky (I prefer to say "blessed") then that cable can be used to communicate via RS-232 (serial comm. port) for programming purposes ...
BUT ...
that 25-pin port (known as Channel 0) can be "reconfigured" to act as something OTHER THAN a programming port ... if that's the case, then you're probably going to need Data Highway Plus communication gear ...
can you post a copy of an existing program file? ... if so, we can tell more about your system ... (and yes, I know that you might not already HAVE an existing program file) ...
BUT ...
if you do NOT have an existing program file, then you're not going to see any helpful comments and other documentation once you eventually get online ... specifically, that type of stuff is NEVER present inside the processor ...
suggested game plan: find an existing program file (.RSP extension) and post it to this thread ...