'uint8_t' instead 'Int'

[nickgammon]

some vars that have value '-1'

You can use "char" instead of "byte".

The char type can hold numbers in the range -128 to +127.

[system]

some vars that have value '-1'

You can use "char" instead of "byte".

The char type can hold numbers in the range -128 to +127.

You CAN also use uint8_t to hold "-1" as long as you realize it's actually 255