Difference between 32 bit and 64 bit apps

Question

Is there any functional difference in 32 bit and 64 bit apps apart from the fact that 32 bit os can only run 32 bit apps whereas a 64 bit os can run both 63 and 32 bit versions of apps?

In: 2

Answer 1

32 bit apps are designed for 32 bit processors and vice versa.

32 bit processor registers can only handle 32 bit (32 1s and 0s) operations per clock cycle. For integers this limits arithmetic between 0 and about 4 billion or 2^32. (Of course there are ways to calculate larger numbers by saving intermediary results into the DRAM, but that costs a lot of time)

64 bit processing increases this 4 billion limit of 32 bit processors to about 16 x 10^18.

32 bit will be backwards compatible on a 64 bit cpu because the 64 bit cpu has more computing “space” and can handle whatever 32 bit operations it needs.