explain how to get from bits value to target

[Giszmo]

For educative mode it would be nice to understand better what the Bits mean.

Bits = 0x190102B1 Target = 2 ^ ( 8 * ( 0x19 - 3 ) ) * 0x 0102B1 = 0x000000000000000102B100000000000000000000000000000000000000000000

so also split "bits" into its two parts (if I understood that right). Bits = 0x190102B1 = 0x19 0x0102B1.