1. A method for controlling a test instrument including a first processor and having a predetermined set of programmable control settings, including: providing a computer including a second processor and having external communications means for transmitting control setting commands from the second processor to the first processor, user input means for a user to enter data to the computer, and a memory; storing, in the computer memory, data defining a transformation function of the test instrument for inversely transforming a generic output for the instrument into a generalized set of said control setting commands for controlling operation of the instrument; entering, in the computer, data that defines a user-specified output for the instrument; inversely transforming the user-specified output in accordance with the transformation function to produce, in the second processor, a specific set of said control setting commands; and transmitting the specific set of control setting commands to the first processor to operate the test instrument in accordance with specific control settings that cause it to produce an output replicating the user-specified output.