4-Bit Parallel-Access Shift Registers

These 4-bit registers feature parallel inputs, parallel outputs, J-K\ serial inputs, shift/load (SH/LD\) control input, and a direct overriding clear. All inputs are buffered to lower the input drive requirements. The register has two modes of operation:

Parallel (broadside) loadShift (in the direction QA toward QD)

Parallel loading is accomplished by applying the four bits of data and taking SH/LD\ low. The data is loaded into the associated flip-flop and appears at the outputs after the positive transition of the clock input. During loading, serial data flow is inhibited.

Shifting is accomplished synchronously when SH/LD\ is high. Serial data for this mode is entered at the J-K\ inputs. These inputs permit the first stage to perform as a J-K\, D-, or T-type flip-flop as shown in the function table.

The high-performance 'S195, with a 105-megahertz typical maximum shift-frequency, is particularly attractive for very-high-speed data processing systems. In most cases existing systems can be upgraded merely by using this Schottky-clamped shift register.