(1) A pattern used to transfer a design onto an object. See photomask.
(2) A pattern of bits used to accept or reject bit patterns in another set of data. For example, the Boolean AND operation can be used to match a mask of 0s and 1s with a string of data bits. When a 1 occurs in both the mask and the data, the resulting bit will contain a 1 in that position.
Hardware interrupts are often enabled and disabled in this manner with each interrupt assigned a bit position in a mask register.
