Holiac A family of student-constructed logic teaching aids

"HOLIAC" is the name of a family of cardboard models of information-logic machines implemented with "peekaboo" logic. "Peekaboo" logic is a representation of switching logic by a display of colored spots in punched windows in cardboard slips. The slips are pushed up or down in various configurations to represent an input statement, and the user scans the resulting display of spots to gain information with which to carry to termination the particular algorithm in use, and to read the final output statement. Holiacs can be used to demonstrate machine applications of conventional-and unconventional number systems, coding and decoding, shift register manipulations, logical operations, and residue number system computations, among other things.