The 281t Quad Function Generator comprises four function generators organized in two pairs. All four generators can operate independently or can be linked in pairs to generate more complex output voltages.

Upon receiving a pulse, a generator’s output voltage ramps up to 10V at a rate determined by the sum of an applied control voltage and the setting of the attack time knob. When in Sustained mode, the voltage will stay high as long as the input pulse is maintained; when not in the Sustained mode, or when the input pulse terminates, the output ramps down to 0V at a rate determined by the sum of the decay cv in and the setting of the decay knob. At the end of the Decay segment, a transient pulse appears at the pulse output. If the 281t is in Cyclic mode, the cycle now repeats.