A 8 bit latch comprises of transparent latch D flip flop. It is commonly used to interface output device with microprocessor. A typical example of such 8 bit latch 74LS373 is shown in figure.
The devices includes eight D latches with tri buffers only on eis shown in figure for clarity 8 input lines ( ID to 8D) are connected to data bus and 8 output lines to output devices. The enable signal is connected to clock ( LK). The enable signal is actives high, when it goes high data are latched from data bus. The output control signal is active low and it enables the tri state buffers to output data to output devices.
The concept of interfacing microprocessor with output device will be one more clear after reading chapter7.