This circuit is a interfacing circuit which is used to interface A-D convertor with a Microcontroller.The MCU is 8031, and the A/D convertor is the ICL7104. The features of this IC is given below.

The ICL7104, combined with the ICL8052 or ICL8068, forms a high performance A/D converter family. TThis IC performs with full three-state output, UART handshake capability, and other outputs for easy interfacing. The chip also offers optional input buffer gain for high sensitivity applications, a built-in clock oscillator, and output signals for providing an external Auto-Zero capability in preconditioning circuitry, synchronizing external multiplexers, etc.

Similarly the features of IC 74LS373, which is a connector between the Microcontroller and the A/D convertor is given below. This IC acts as a Latch which consists of eight latches with 3-state outputs for bus organized system applications. The flip-flops appear transparent to the data (data changes asynchronously) when Latch Enable (LE) is HIGH. When LE is LOW, the data that meets the setup times is latched. Data appears on the bus when the Output Enable (OE) is LOW. When OE is HIGH the bus  output is in the high impedance state.