BIT

Read or write one bit of an integer variable. Bits are numbered 0 (least significant) to 63.

value = BIT(intvar, bit) BIT(intvar, bit) = 0|1

intvar - an integer variable or array element bit - bit index 0..63 using 64-bit two’s complement

The read form returns 0 or 1 and also accepts a value instead of a variable. The assignment form sets or clears the bit in place; the variable must be an integer.

Example:

DIM A AS INTEGER
A = 0
BIT(A, 3) = 1
PRINT A
PRINT BIT(A, 3)
BIT(A, 3) = 0
PRINT A

Source: docs/help/bit.txt inmmcore. On the computer, typeHELP BIT.