What is the PROM and which are the advantages and the disadvantages?

Answer 1

PROM ('Programmable Read Only Memory')
is an (almost) obsolete type of non-volatile memory device. Internally it can be thought of as a series of Fuses that are 'blown' (or not) in order to record data (0's & 1's)

Advantage - it is not possible to 'un-blow' the fuses, so it's essentially impossible to 'remove' the contents.

Disadvantage - as above, so it's not possible to update the contents with replacemnet data.

About the only place where you might find then in use is Printer Ink Cartridges - where 'fuses' are blow to record the ammount of Ink used. This stops you 'unusing' the Ink (Manufacturers do not want you refillng the the Cartridges :-) )