Abstract: A shift register, circular pointer or ring counter presents a reduced capacitive load on the clock and shift signals used to control it. The device is constructed using one or more enhanced data cells. Each data cell has a data input, a data output, a clock input and a shift input. The data output of each cell is coupled to the data input of an adjacent cell. At least one pass-AND gate is provided for each cell. The pass-AND gate has a switching input and a switched input. The switching input operates to toggle the input capacitance of the switched input between a larger and a smaller value. The logical OR of the data input and data output of each cell is used to drive the switching input of the associated pass-AND gates for that cell. The switched input of the pass-AND gate is adapted to be coupled to the clock (or shift) signal, and the output of the pass-AND gate is coupled to the clock (or shift) input of the data cell.

Abstract: A method and apparatus is disclosed for reading data from and writing data to remote registers that are dispersed throughout an integrated circuit chip. Regardless of the size or number of remote registers involved, the operation is accomplished using only two interconnect lines, plus a clock. Each remote register is associated with a unique address. During a write operation, a microprocessor loads the write data into a staging register, loads the destination address into a header generation register along with a read/write control bit, and loads a count value into a clock. Thereafter, the apparatus of the invention proceeds automatically, as the clock counts down, to shift the data onto a serial data line following a header. Each of the remote registers in the system are arranged serially, and each monitors the header information, comparing the address contained in the header with its own address.