The SCIDAR consists basically of an image-acquisition system and processing computer. The main needs are: Short-exposure-time frames (1 ms), low read-out noise, fast image transfer, near-real-time computing of the image correlations. The optics (made of one or two lenses) form images of a virtual plane located a few kilometers below the pupil. Our system is based on a 80x80 CCD from Marconi, which will deliver one frame every ~5 ms, with ~7 electrons readout noise. All the detector electronics is developed at the Instituto de Astronomia. The CCD is controlled using a DSP. Another DSP reads the images, which are then sent to the principal computer that works under Linux. The correlations are calculated on this computer. Finally, the principal computer sends the results to the observing-room computer where they are displayed and stored.