The Thor 20 and 21 were very expensive (a 12.5 MHz Thor 21 costing around twice as much as a Thor 1F) and were mainly placed on loan to the software development community.
Thor 20 ir 21 buvo labai brangūs (12,5 Mhz Thor 21 kainavo daugmaž dvigubai daugiau nei Thor 1F) ir buvo daugiausia paskolinti programinės įrangos kūrėjų bendruomenei.