Offering low power delta-sigma 20-bit data acquisition for the PC/104 bus, 4A23 board has 16 single-ended or 8 differential input channels with 500V isolation from system ground. The analog inputs have software selectable 25 mW, 50 mW, 1V, 2.5V and 5V full scale ranges. The galvanic isolation of input signals from the computer system ground eliminates ground loop problems common with high resolution A/D converters and allows floating measurements. The conversion rate can be traded off with resolution to match the application. Conversion rate can be programmed from 202 down to 3.76 conversions per second with corresponding noise limited resolutions of 10 to 20 bits. Calibration is stored in an on-board EEPROM so no zero or full scale adjustment potentiometers are needed.