The unbalance in computing speeds of the various components of present hybrid computers places a constraint on the maximum iteration rate, and hence minimum solution times, that can be achieved. This is particularly true with the mode switching of operational amplifiers, where the main limitations of practical devices are those of accuracy and bandwidth.The design of a 2-mode switch is presented, the criteria chosen being 0.1% accuracy and 10kHz bandwidth. The switch comprises m.o.s.t.s used in the feedback path of a cheap monolithic amplifier. The stability of such a switch is analysed and it is shown that an improved performance can be achieved by the use of feed-forward techniques.