In this paper a large memory fast data acquisition system is presented, giving special attention to the architecture and suitability of Linux for use in this type of applications. The system will be used to acquire data from JET's new correlation reflectometers composed by four microwave channels of four analog signals each. The sixteen signals will be acquired by fast acquisition 12-bit channels at 2Msamples/s achieving a data rate of 60Mbytes/s. These sixteen signals will also be acquired by slower acquisition channels, with 16-bit resolution and sampling rates up to 250kSPS. Two Digital Signal Processors will run an algorithm over this data to avoid the use of the old KG8B RMS analog circuits as well as control and generate all the timing and acquisition clocks needed by the system.