y= a bitclear b
a bitclear b clears the bth bit of a. Both a and b are treated as 32-bit (4-byte) integer values, so an eventual fraction will be ignored.
In 20-sim, all bitwise function arguments are treated as 32-bit integers. Thus the binary representation of 30 (ignoring leading zeroes) is equal to 11110 as shown in the figure below. The operation 30 bitclear 3 clears the 3rd bit of 11110 which gives 11010. This binary value has a decimal value of 26.
a and b must be integers.