A high-speed, 8-channel, 8-bit ratiometric data acquisition system, LPT8AD8 has an on-board 10-MHz clock with a conversion time of 6.7µs with a throughput to the parallel port in excess of 75 ksps. Input voltage range is 0V to 5V, and the difference between the positive and negative reference input voltages is digitized into an 8-bit data word. A complete 8-channel, 12-bit data acquisition system, LPT8AD12 board contains a 2-MHz on-board clock and a precision voltage reference. Requiring a 5V power supply, programmable ranges are 0V to 5V, 0V to 10V, ±5V and ±10V. Conversion time is about 10µs with a throughput to the parallel port in excess of 75 ksps.