The Thor 20 and Thor 21 were variants of the Thor PC launched in April 1987, fitted with a 68020 processor on a daughterboard in place of the original CPU. The new processor ran at 12.5 MHz, a 16.67 MHz option also being offered at higher cost. The Thor 21 was also fitted with the 68881 floating-point co-processor, running at the same speed as the CPU. Performance was significantly better than the Thor 1, but handicapped by the use of the 8-bit memory of the base system.