Both of these flip-flops can be set/reset/unchanged under program control, and their state examined for branching etc. For example a full-adder requires a 1 bit carry flip-flop to keep the carry between each bits as they are added, or a delay flip-flop that allows implementing shift up/down operations. note OR is not needed as it is "baked into design") or 1-bit state "machines". These are either simple logical gates (NOT, NAND, XOR etc. If the word length is n bits, after n cycles the value in register is unchanged. In simplest form, they are shift registers with common clock - at each clock time 1 bit is presented to their outputs (going into switch matrix) and 1 bit picked up on opposite side (from switch matrix). This way, logical OR can be implemented on any number of inputs simply turning on multiple switches in a column (of course, an opposite implementation could generate a wired AND) It is important to note that output column wires have "pull-down" - this means if no switch is on in that column, the output will be 0. Any number of switches can be on or off, and this is done under program control (microcode, or state machine).
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