The ROMs on most DECstations are little square things with a notch out
of the corner, rather than rectangular things with rows of pins on the
long sides.   They do not live on the daughtercard.   I believe they
are socketed, though, so you should be able to update your old /240 if
you have an appropriate pod for your PROM burner.   Field Circus might
also be able to update you, for a price.   I've found that their
prices for part swaps usually aren't too bad, although figuring out
what part you need to swap can be hella tricky.

			       _MelloN_