This is a board with an ADC0804, which is an 8-bit Analog-to-Digital converter that uses a differential potentiometric ladder. These converters are designed to allow operation with derivative control bus with 3-state output that connect directly to the data bus. These A/Ds have I/O ports that connect to a microprocessor. Differential analog voltage inputs allow for increased mode rejection and analog zero input compensation. In addition, the voltage reference input can be adjusted to allow the encoding of any smaller analog voltage spanning the full 8 bits of resolution.
