The LF synthesizer PM 5190 is a versatile high performance signal generator. It produces three wave forms, namely sine wave, square wave or triangular wave form in the frequency range from 1mHz to 2MHz. The instrument is designed for most professional applications, where a stable signal source is asked for, for development laboratories, including calibration purposes and advanced educational programs. The frequency settings of the synthesizer are highly accurate due to X-tal controlled generation. All basic signal parameters, i.e. frequency, amplitude, dc offset and wave form are set via keyboard in the local mode of operation. In addition all these parameters are remotely programmable via the built-in IEC bus interface. In local as well as in remote operational mode these parameters are indicated by a bright seven segment LED display in combination with dimension and wave form LED1s. A microprocessor represents the central data processing and control unit of the instrument. It accepts input data from the keyboard or via IEC bus. After diagnosting and processing these data it stimulates the various functional units of the instrument for proper response via assigned I/O ports. In case of incompatible settings the microprocessor initiates the LED display flashing. A rub-out facility allows fast alteration or correction of keyboard input data. The inherent signal generation technique of the instrument is called direct digital signal synthesis: Succeeding digital samples of the signal are computated by a fast processing TTL circuitry and converted to analogue. This technique effects extreme fast responding on alternate frequency settings. Remote data programming is organized according to the international standard “Interface System for Programmable Measuring Apparatus", called IEC bus. So via the built-in IEC bus interface the PM 5190 cooperates with all Philips and non-Philips IEC bus instruments. The dc output voltage may be selected separately or whenever used as dc offset voltage added to the output signal. The generator provides external amplitude modulation facility. For TTL circuitry testing and stimulating a separate TTL output is available. All these facilities are built into a compact portable housing* The clearly designed frontpanel and the simplicity of keyboard input as well serve for convenient operating the instrument.