A second PCI board in addition to the PCI A/D Data Acquisition Board is required in Sciencetech's linear and area array detectors such as the LDA-2000 (Photo-diode array), linear CCD, linear InGaAs, and Area CCD detector systems when uses with Sciencetech Sci-LDA and Read-LDA software. This PCI board is essentially a counter used for clocking and data synchronization purposes. This counter board is also required in Sciencetech's Photon Counting PMT Detectors, but not the A/D Data Acquisition Board itself. The Photon Counting version includes the counter board, Sci-Spec (with photon counting feature) software, and cable between the Sciencetech Photon Counting PMT detector and PCI counter board.