The CDx4HC(T)259 8-bit addressable latches are designed for general-purpose storage applications in digital systems. Specific uses include working registers, serial-holding registers, and active-high decoders or demultiplexers. They are multifunctional devices capable of storing single-line data in eight addressable latches and being a 1-of-8 decoder or demultiplexer with active-high outputs.

Four distinct modes of operation are selectable by controlling the clear (CLR) and enable (G) inputs:

• Addressable-latch mode: CLR = HIGH; G = LOW
  • Data at the data-in terminal is written into the addressed latch
  • The addressed latch follows the data input, with all unaddressed latches remaining in their previous states
• Memory mode: CLR = HIGH; G = HIGH
  • All latches remain in their previous states and are unaffected by the data or address inputs
  • To eliminate the possibility of entering erroneous data in the latches, G should be held high (inactive) while the address lines are changing
• 1-of-8 decoding or demultiplexing mode: CLR = LOW; G = LOW
  • The addressed output follows the level of the D input with all other outputs low
• Clear mode: CLR = LOW; G = HIGH
  • All outputs are low and unaffected by the address and data inputs