.chk

.chk label

Calculates an 8-bit checksum made up of the sum of all the data between the current instruction pointer and the specified label. Does not produce the same results as TASM, so this is not a recommended directive.

_label:
    .db 1
    .db 4
    .db 54
    .chk _label ; Has a value of 59 with Brass, 51 in TASM.

The least significant byte is all that is used.