Overview: www.DataSheet4U.com HD74LS165A
Parallel-Load 8-bit Shift Register
REJ03D0449–0300 Rev.3.00 Jul.15.2005 The LS165A are 8-bit serial shift registers that shift the data in the direction of QA toward QH when clocked. Parallel-in access to each stage is made available by eight individual direct data inputs that are enabled by a low level at the shift / load input. These registers also feature gated clock inputs and complementary outputs from the eighth bit. All inputs are diode-clamped to minimize transmission-line effects, thereby simplifying system design. Clocking is accomplished through a 2-input positive-NOR gate, permitting one input to be used as a clock-inhibit function. Holding either of the clock inputs high inhibits clocking and holding either clock input low with the shift / load input high enables the other clock input. The clock-inhibit input should be changed to the high level only while the clock input is high. Parallel loading is inhibited as long as the shift / load input is high. Data at the parallel inputs are loaded directly into the register on a high-to-low transition of the shift / load input independently of the levels of the clock, clock inhibit, or serial inputs.
