This chapter presents several applications of the computer as a tool that are significant in the analysis of the very complex data that come from brain systems. The chapter discusses a model of brain tissue, which has three compartments. The neural compartment is composed of nerve cells. The second component of the tricompartmental arrangement is a neuroglial compartment. Between the neuroglia and the neuron is a substance, which is a hydrated net of large molecules, mucopolysaccharides, and mucoproteins, specially developed under synapses, and which plays a role in the excitability of the cell. The chapter discusses the types of data that are collected for computer analysis. There are two main varieties of codes. One is widely used in the laboratory and can be generated as a 3-digit 4-bit member in binary coded decimal (BCD). The second group of codes includes so-called IRIG A and B methods that may give a faster coding cycle, but are not usually compatible in their speed with a typical EEG paper record because they are written very fast, and thus cannot be interpreted. The first step in preparation of data for handling by the computer involves analog-to-digital conversion. Secondly, the data sampling rate must bear a relationship with the bandwidth of the data. A typical modern analog-to-digital converter for electrophysiological studies incorporates a multiplexing input to handle 10 to 30 channels of data. Some computational techniques can be used on-line; how much can be done depends upon the size of the central processor and the mode of access to it. One may choose to start simply by averaging, or by correlation analyses.