The Model 278, a 0.01 Hz to 12 MHz Programmable Synthesized Function Generator, can operate in con- tinuous, triggered, gated, burst, synthesized, external reference, or external phase lock modes with output levels to 20 volts peak-to-peak. The synthesized mode has 5 digits of frequency resolution with 0.0005% accuracy, or it can be locked to an external 10 MHz (zero-crossing or TTL) fre- quency reference for greater accuracy and stability. In addition, the separate synthesizer circuit acts as a highly accurate internal trigger source. The generator can produce sine, triangle, square, square complement, and pulse waveforms as well as dc and external width.. Data entry is from the front panel or GPIB (IEEE-488, 1978). Numeric input is entered in free format: fixed, floating, or exponential notation. Parameters may be entered in any order. Internally, all entries are interac- tively checked for errors and displayed on the front panel, or they may be accessed through the GPIB.