Some of these are straightforward from the preposition: inscribe, describe (write about).

Sometimes the visual imagery is fairly obvious:

subscribe = write one's name down on a list under other people's names
prescribe = write down beforehand, for someone else to use

Others you really need to know the circumstances in ancient Rome for them to make sense:

conscript(ion) = enrolling, writing down on a roll with other people's names
proscribe = write down publicly, to inform people of a ban (pro- "forward" being used unusually for "public", if my good book is to be believed)