-- r1 will be the temp in fahrenheit
-- r2 temp in celsius
-- r3/r4/r5 will be used by constants
-- (f - 32) * 5 / 9
li r1, 100
li r3, 32
li r4, 5
li r5, 9
sub r2, r1, r3
mul r2, r2, r4
dir r2, r0, r2, r5
tx